TAM, SAM and SOM for a Service Business: Count Your Local Market

Say a commercial HVAC department works within 40 miles of Columbus. Its local TAM is 3,807 building sites, its SAM is 912 fitting prospects, and its three-year SOM is 27 active service agreements. At $7,820 a year per agreement, that last number means $211,140 of annual service revenue by the end of year three.

The three trade examples below are planning models, with stated assumptions for cleaned building counts and account economics. The Columbus starting count is sourced. A November 5, 2026 query of Franklin County’s official tax-parcel layer returned 3,304 records across selected office and shopping-center classes plus warehouses, all with positive building area. The worksheet shows the bridge from those parcel records to the modeled territory.

Ground Control by PorchRocket gives you the matching property count and exact list price for your chosen area before you buy. That lets you put an address list behind the market estimate, then decide which accounts deserve a salesperson’s Tuesday morning.

What do TAM, SAM and SOM mean for a service business?

TAM covers everyone who could buy a defined service, SAM covers the customers your operation can serve, and SOM covers the portion you can win within a stated period.

Spell them out once in your plan: total addressable market, serviceable addressable market and serviceable obtainable market. All three need a service definition. If your HVAC department handles light-commercial rooftop maintenance but cannot dispatch refrigeration technicians, counting restaurants that need refrigeration coverage would inflate the market estimate while sending your salesperson after scopes the service manager would have to decline.

For an owner, I would start with one offer and a local boundary. A national figure can sit beside it for context. Put the geography beside each number so a reviewer can compare territories without working backward from a sales percentage.

Measure	The owner’s question	Calculation for a building service	What changes the number
TAM	How much demand exists for this offer in the defined market?	All eligible building sites x annual service revenue per site	Geography and service definition
SAM	Which sites fit the business we can operate?	Eligible sites remaining after territory, size and service filters x annual revenue	Equipment, building size and route requirements
SOM	What can we win and serve by a stated date?	Retained accounts won, capped by delivery capacity, x annual revenue	Sales hours, conversion, renewal and available crews

Keep the building count visible beside the dollars. A $7 million opportunity spread across thousands of tiny stops calls for a different operation from the same opportunity concentrated in industrial parks where a technician can finish one maintenance visit and drive two minutes to the next account.

The SBA’s market research guidance treats market size and customer location as separate questions, alongside saturation and pricing. Your worksheet should do the same. Counting potential customers answers only the first question. It does not tell you how many already have an incumbent, what they spend or when they will review the agreement.

Top-down vs. bottom-up market sizing

Bottom-up sizing multiplies counted buildings by the service revenue they could support; top-down sizing starts with a larger market estimate and assigns a portion to your territory.

I would use bottom-up sizing to decide whether to add a technician or open a branch. Check the addresses against work you already price profitably before committing wages and a vehicle. Sales can start with those same addresses.

Top-down figures still provide a reasonableness check. EIA’s 2018 CBECS Table B1, revised in December 2022, estimates 5.918 million U.S. commercial buildings and 96.423 billion square feet. Those are 2018 survey estimates, even when you consult them in 2026. Do not relabel them as a 2026 building census.

A population-share shortcut assumes your territory has the same building mix and service spending as the larger market. That assumption can swamp the answer. A distribution corridor and a downtown office district put different work on a truck.

Use a top-down estimate to question an implausible bottom-up result. Investigate the difference rather than averaging the two numbers. Check for repeated parcels, residential properties included under a broad commercial label, or a project value multiplied by every building every year.

The address work belongs in your commercial building count. The broader market intelligence guide connects that count to property fit and buying information.

Which data sources count buildings in 2026?

County property records supply the local inventory and Census supplies business activity; use EIA’s dated building-stock estimates to check the scale of the segment you are studying.

Start with the unit recorded in the source. A parcel is a land record. A building is a structure. A buying account is the customer who approves your scope. Keep separate identifiers for each, even if your first spreadsheet contains only a few hundred rows.

Source	What to take from it	How to use it in market sizing	What to check before multiplying
EIA CBECS	Building counts, floorspace and activity categories	Check whether your proposed segment has a sensible scale	Survey year and the survey’s definition of commercial
Census County Business Patterns	Employer establishments by industry and geography	Compare customer-industry concentration across territories	Establishments can share buildings
County auditor or assessor	Parcels, recorded uses and available building fields	Assemble the local inventory and reconcile addresses	Multiple parcels per site and multiple buildings per parcel
Ground Control	Matching properties and reasons for the match	Count buildings by trade fit and buy the selected list	Keep the selected territory and filters with the count
Your job and customer records	Agreement prices, service hours and renewal history	Price the segment and set a delivery limit	Separate recurring work from occasional projects

County Business Patterns publishes business statistics by industry and geography. The program page featured 2023 data when checked for this November 2026 article. Save the reference year from the download with your worksheet.

The Census glossary defines an establishment as a single physical business location and distinguishes it from an enterprise with multiple establishments. CBP covers locations with paid employees and excludes nonemployer businesses. Ten tenants in one office building therefore need building-level reconciliation before you count ten roof-maintenance opportunities.

Local tax categories need interpretation too. Ohio’s property-classification rule includes apartments within commercial property and assigns vacant commercial land code 400. Searching for every commercial parcel would bring both into the starting inventory.

For the Columbus worksheet, query the county layer’s CLASSCD field for these codes: 350, 425, 426, 447, 448, 449, 480. Require BLDGAREA greater than zero. The radius query uses a model depot at longitude -82.9988, latitude 39.9612 and a 40-mile buffer. It covers the Franklin County portion, rather than neighboring counties.

The county’s Web Reporter offers current-tax-year downloads with parcel and building-card fields. Use those fields for reconciliation, then retain the extraction date. Keep unresolved rows in a review tab instead of quietly counting them as fitting buildings.

Draw a service boundary your trucks can cover

A 40-mile circle should define the starting search area, while route time and service commitments decide which buildings enter the operating territory.

Choose a depot first. Measure the boundary from the place your technicians start, rather than from the city label on a map. Record any excluded corridors and the reason for excluding them. A radius with no operating rules can add sales opportunities faster than it adds profitable service stops.

For the Columbus HVAC offer, the worksheet includes office buildings and shopping centers as well as warehouses within the search boundary. SAM requires at least 25,000 square feet with five or more visible rooftop units. Check the access requirements too.

Equipment count is a reason to investigate an account. Before pricing the agreement, the estimator needs an equipment schedule and a site walk that establishes how the crew will reach the roof and how much scheduled service the proposed scope will consume across the year. Budget the visit.

Write down a minimum annual account value and an available service-hour allowance. Both are management choices you can test against your job history. An attractive building outside the regular route can stay in TAM while failing the current SAM rules.

For a second depot, repeat the count from that location. Do not add two overlapping radius totals. Assign each building one territory and keep an overlap column until the routing decision is settled.

That same discipline carries into building-product territory planning, where a distributor or manufacturer needs to distinguish the building opportunity from the dealer or branch responsible for pursuing it.

The Columbus HVAC market-sizing worksheet

The HVAC model produces a $29.77 million local TAM, a $7.13 million SAM and a $211,140 annual SOM at the end of year three.

The service is an annual rooftop HVAC maintenance agreement priced at $7,820 per building. Use that same price throughout this first worksheet to isolate the effect of narrowing the count. A larger study should price separate building bands from the contractor’s own agreements.

Start with the 3,304 county parcel records. Assume reconciliation removes 126 repeated or shared-site records and adds 629 eligible building sites in neighboring counties inside the boundary. The local building-site inventory becomes 3,304 - 126 + 629 = 3,807. Those adjustments are worksheet inputs to replace with reviewed addresses.

HVAC worksheet line	Building or account count	Arithmetic	Annual revenue basis
Local TAM for the selected property types	3,807	3,807 x $7,820	$29,770,740
SAM after size, rooftop-unit and operating filters	912	912 x $7,820	$7,131,840
Sales-supported active accounts at year three	27.1	10 + (10 x 90%) + (10 x 90% x 90%)	Before rounding
Service capacity for added accounts	30	1,440 available annual hours / 48 hours per account	Capacity ceiling
Planned year-three SOM	27	27 x $7,820	$211,140

All three trade models start with no existing customers for the offer and count one independently purchased service scope per building site. Prices and margins stay constant over each projection; the SAM counts are assumed filter results. Sales works 300 different fitting prospects per year for three years, leaving 12 of the 912 outside the initial campaign. At a 40% conversation rate, 120 buyers speak with the team. Half agree to a survey, two-thirds of those surveys produce proposals, and one-quarter of the 40 proposals become agreements: 10 wins.

Apply a 90% annual renewal assumption. The first year’s 10 agreements contribute 8.1 active accounts at the end of year three; the second year’s cohort contributes nine; the newest cohort contributes 10. Round 27.1 down to 27 for the staffing plan.

Capacity passes the test: 27 x 48 hours = 1,296 annual service hours against 1,440 available. Because the 48-hour allocation already includes travel and scheduled work, the service manager can compare the proposed book with available hours without adding a second travel allowance or assuming every technician hour will be spent with tools on equipment. Reserve the remaining 144 hours.

At an assumed 42% service gross margin, each agreement contributes $3,284.40 a year before overhead and acquisition expense. The year-three book contributes $88,678.80. That is the number to compare with the added overhead required to support the work.

A roof-maintenance market with project upside

The roof-maintenance model supports 28 active agreements at year three, worth $89,040 in annual maintenance revenue before any separately approved project work.

Use a 35-mile territory for a commercial roof-service crew. Set local TAM at 2,468 building sites and price the annual inspection and maintenance offer at $3,180. Annual TAM is 2,468 x $3,180 = $7,848,240.

Apply the service filters: commercial buildings of at least 25,000 square feet, membrane roofs, a 10+ roof-age band and an operating location the crew will serve. Set SAM at 684 building sites, or 684 x $3,180 = $2,175,120 annually.

The sales plan works 200 different fitting sites each year: 40% yield conversations, half of those yield proposals, and 25% of proposals close. That is 200 x 40% x 50% x 25% = 10 added agreements annually, from 600 sites over three years. With 95% annual renewal, the year-three account count is 10 + 9.5 + 9.025 = 28.525. Available annual maintenance capacity is 672 crew hours, and each agreement consumes 24 hours including its assigned travel. Capacity is 28 agreements, so SOM stops at 28.

Use the commercial roof list to identify the target segment. Ask the owner or manager who approves roof work and when inspections are scheduled. Count one maintenance scope once, even when several recorded parcels sit beneath it.

Project upside belongs on another line. Assume the maintenance book produces three separately approved jobs over three years at $64,750 each. That is $194,250 of project revenue over the period. At a 29% project gross margin, it contributes $56,332.50 before overhead.

Do not add that three-year project total to one year’s maintenance TAM. Keep the time labels attached. Before adding a recover or replacement project to the production forecast, have the estimator review the proposed assembly and access requirements, then assign the crew hours and material allowance against the same job rather than against the whole maintenance book.

For a coating offer, inspect the assembly and decide the scope before putting coating dollars against a prospect. The market count should give the estimator the roofs worth visiting without pre-selling a repair method.

A sealcoating market measured by buying cycle

The sealcoating model has 516 fitting properties, an annual equivalent of 129 buying opportunities and a three-year SOM of 24 completed jobs.

Set the local inventory at 2,941 properties with paved parking areas inside a two-truck crew’s 35-mile territory. The proposed package is crack fill, sealcoat and restriping at an average project price of $7,860.

Assume a four-year buying cycle for the worksheet. That makes annual TAM 2,941 / 4 x $7,860 = $5,779,065. Use the contractor’s own customer history and site assessments to replace that cycle assumption when preparing the sales schedule.

Narrow SAM to 516 sites whose lot scope and scheduling fit the crew’s operating territory. Annual equivalent SAM is 516 / 4 = 129 projects, worth $1,013,940. Over three years the even-cycle assumption produces 387 buying opportunities.

Paving measure	Count	Revenue	Time basis
Installed fitting site base	516 properties	Not multiplied as annual jobs	Inventory
Annual equivalent SAM	129 projects	$1,013,940	One year
Available buying opportunities	387 projects	$3,041,820	Three years
Planned SOM	24 jobs	$188,640	Three years
Average annual SOM	8 jobs	$62,880	One year

The crew works 120 different due-cycle prospects annually. At a 40% conversation rate, 48 buyers respond; two-thirds receive proposals, and 25% of those 32 proposals close. That produces eight added jobs from 120 prospects, within the 129 annual buying opportunities. At two crew-days per job, it needs 16 available crew-days annually for this campaign. Its assumed 34% gross margin produces $64,137.60 across the 24 jobs. Overhead and acquisition expense come out afterward.

The three-year share is 24 / 387, or approximately 6.2% of buying opportunities. Reporting 24 / 516 would answer a different question: the portion of the installed site base served during those three years.

Start the inventory with properties that have paved parking areas. Measure the asphalt and confirm the scope during the site assessment. Then ask when the owner last bought the service and when they plan to buy again. Replace the evenly spread cycle with those dates as the campaign develops.

How much of your SAM can you win in three years?

Calculate three-year SOM from annual wins and retained accounts, then cap it at delivery capacity; a guessed 5% market share skips the sales and staffing work.

For recurring agreements, calculate each year’s surviving cohort. For projects, count the jobs that can reach an award and fit the production calendar during the period. Keep those two models separate when presenting the result.

The HVAC plan’s 27 active agreements represent 27 / 912, or approximately 2.96% of SAM. That percentage falls out of the plan. It was never the starting assumption.

Test annual wins against the staffing ceiling. Hold the 912-building SAM, $7,820 annual agreement and 90% renewal assumption steady. Vary annual wins while keeping added service capacity at 30 accounts.

HVAC case	New agreements per year	Retained accounts at year three	Planned accounts after rounding and capacity	Annual service revenue
Low	6	16.26	16	$125,120
Base	10	27.10	27	$211,140
High	14	37.94	30	$234,600

The high case needs a staffing decision before sales accepts every agreement. The low case needs a spending decision: can $125,120 of annual service revenue carry the proposed overhead at the modeled margin?

Measure the bottleneck before hiring. If surveys convert poorly because the buildings are too small, another salesperson repeats the same problem. If fitting accounts are closing and the service calendar is full, technician capacity becomes the constraint.

Keep a reason for every lost proposal. A buyer whose incumbent agreement runs through next September should stay in SAM with a future action date, while a building that requires a service you do not offer should leave the serviceable segment until your operating capabilities change. Adjust the forecast accordingly.

The sales pipeline worksheet works backward from the revenue target to required conversations. Use it beside the market count to check whether the weekly activity fits the salesperson’s calendar.

The same sales hours on a better-fit list

In the 100-building HVAC campaign, better targeting raises wins from one agreement to three within the same 76 sales hours, cutting acquisition cost despite a paid property list.

Give both campaigns 76 staff hours at a loaded $42 per hour, plus $1,380 for contact research and campaign expenses, including mail and travel. The broad campaign starts with free addresses, making its total cost $3,192 + $1,380 = $4,572. The targeted campaign adds 100 Ground Control buildings at the published upper price of $20 each, bringing total cost to $6,572.

The targeted campaign spends more of its hours reaching buyers and following up on fitting scopes. Use these stage assumptions:

Campaign result	Broad address list	Ground Control fit list
Buildings worked	100	100
Total staff hours	76	76
Two-way buyer conversations	20	40
Qualified proposals	4	12
Proposal win rate	25%	25%
Agreements signed	1	3
Total acquisition spend	$4,572	$6,572
Customer acquisition cost	$4,572	$2,190.67

Use the same $7,820 account value and 42% gross margin in both columns. Annual gross profit per account is $3,284.40. Count five service years from each signing, with 90% annual renewal, no price or margin growth, and no discounting. Budget ongoing account service in the gross margin and assume no separate renewal-sales expense. Expected gross profit is $3,284.40 x (1 + 0.9 + 0.81 + 0.729 + 0.6561) = $13,449.94644, rounded to $13,449.95 per account.

Three accounts produce about $40,350 over five years. That is about 20 times the $2,000 property-list cost. For campaign ROI, carry unrounded account values into the total: three accounts yield $40,349.84 to the cent. Including every acquisition cost, ($40,349.84 - $6,572) / $6,572 is approximately 514%. Gross profit is approximately 6.14 times total acquisition spend.

The $2,000 list is one input inside a $6,572 sales campaign. Use the same cost definitions when comparing territories in the lead-list ROI guide.

CAC payback is about eight months: $2,190.67 / ($3,284.40 / 12). Two new agreements contribute $6,568.80 in first-year gross profit, just short of the campaign cost; three pass first-year break-even. Repeat the calculation with your own service hours in the lead-list ROI calculator and customer lifetime value calculator.

Annual market size, lifetime value and double counting

Annual market size measures one year’s service revenue, while lifetime value measures one account’s gross profit across several years; mixing those time periods inflates the opportunity.

Keep a building sheet and a buyer sheet. Six buildings can belong to one buying account, but six tenants in one building might have separate HVAC responsibilities. Ask who owns the equipment and who approves your scope before grouping the rows.

For roof maintenance, one owner with six buildings could mean six site scopes under one commercial relationship. Record both the relationship count and the service-site count. Sales capacity follows relationships; inspection hours follow sites.

Existing customers stay in SAM when they meet the filters. Subtract them to calculate the unserved prospect pool, and retain both totals. An existing agreement counts toward current market share, not next year’s new wins.

Separate installed stock from near-term demand. The sealcoating example has 516 fitting properties but only 129 annual equivalent opportunities under the cycle assumption. The HVAC example sells recurring annual service. Neither denominator should be copied into the other’s revenue formula.

Put additional services in a share-of-wallet column. A maintenance customer may also buy repair work, but that revenue needs a scope and a schedule. The contractor lifetime-value guide shows how account economics can inform targeting without changing the annual TAM definition.

Putting TAM, SAM and SOM in a plan, loan or sale

A reviewable market plan needs four items on the same page: the property count, annual revenue formula, three-year sales bridge and crew-hour limit.

I would put the operating decision at the top: add a service vehicle, fund a salesperson or enter another territory. Then show which part of the market estimate supports that decision. A large TAM alone does not explain the expense.

Include a source note with the extraction date and definitions. Attach the deduplicated inventory and filter rules. Each revenue line should trace back to a building count and an agreement value, followed by the sales assumptions and crew hours that support it.

For a loan discussion, put cash timing beside annual revenue. An agreement beginning service in October contributes only the remaining calendar year’s work to that year’s revenue. Include wages and materials needed before collection in the launch budget. A profitable agreement can still require cash to start.

For a sale discussion, show current accounts and retained revenue separately from the unsold opportunity. Support existing performance with customer and job records. Use SOM for the expansion plan rather than describing the whole SAM as future contracted revenue.

Public work belongs in a separate channel. Bid Control by PorchRocket follows public opportunities from cities and counties as well as school districts. It brings bid documents and past awards together. Count the contract’s sites and term once, then allow for the bid calendar in the sales forecast. A school district’s buildings should not appear again as independent private-owner prospects.

Use the same worksheet to compare expansion options in the new-city service-business guide. A smaller territory with a stronger serviceable segment can support the next crew sooner than a larger territory with fewer fitting buildings.

How to calculate your market size, step by step

Build the first market worksheet in 30 days around one offer and a 100-building campaign, then use the early evidence to decide the next sales expense.

1. Days 1 and 2: define the offer. Write the service, annual account value and operating boundary on the first row. For the HVAC example, use a $7,820 rooftop maintenance agreement inside 40 miles. Keep replacement projects on another line.
2. Days 3 through 5: assemble the starting inventory. Pull county property records and a Census industry cross-check. Save the source year and extraction date. Use building and buyer identifiers so one property does not become several prospects through repeated imports.
3. Days 6 and 7: count the fitting segment in Ground Control. Pick the area, office, retail or warehouse types, a 25,000+ square foot size band and 5+ visible rooftop units. See the matching count and price before buying. Order the first 100 buildings at $10 to $20 each, with the file within 48 hours after payment.
4. Days 8 through 10: reconcile the list. Remove current customers from the new-account campaign. Group shared buying responsibility where confirmed, and keep separate site scopes. Add owner information or decision-maker research when the campaign needs those paid add-ons.
5. Days 11 through 14: calculate capacity. Ask the service manager for available annual hours after current commitments and reserve time. Divide by hours per added account, including travel. Use the smaller of the sales-supported account total and the staffed capacity.
6. Days 15 through 24: work the first campaign. Track buildings attempted, buyer conversations, surveys and proposals. Budget follow-up hours. Ask each buyer when service is reviewed and record the next action date, including the buyers who will not quote this month.
7. Days 25 through 27: update the money. Replace the assumed proposal count and expected agreement value with campaign evidence. Carry still-open proposals as open. Calculate CAC and gross-profit payback from all campaign spending, including paid staff time.
8. Days 28 through 30: set the next spending gate. Approve the next batch only if property fit, buyer access and service margins support it. Keep later-stage conversion provisional until proposals reach decisions. Update low, base and high SOM before approving a permanent hire.

Keep the dated inventory beside the campaign activity record. Review again after the first proposal cohort reaches buying decisions. Use signed agreements and recorded losses to update conversion; keep open proposals in their own column.

When should you expand into another city?

Expand when the next territory offers enough fitting accounts to cover its added costs and your current territory’s remaining SAM cannot meet the growth target within capacity.

Compare cities using the same service and size filters. Count the overlapping sites once. Price the extra travel and service coverage before comparing revenue potential. A large building count outside the depot’s operating reach still needs an operating plan.

Calculate a branch hurdle from annual gross profit. At $3,284.40 per HVAC agreement, divide the assumed $72,000 of added annual branch overhead by account gross profit. The result is approximately 21.92, rounded up to 22 active agreements before acquisition spending. That hurdle absorbs most of the base case’s 27-account SOM.

The timing matters. The branch must carry costs while the account base grows. Put the required cash and the agreement ramp beside the end-of-year-three result before signing a lease.

I would first count the unworked buildings near existing accounts. If those sites can fill the next route with less added overhead, compare that campaign with the branch proposal. Use the route density worksheet to price service travel and sales territory planning to assign the remaining accounts.

Review the territory quarterly. New customer wins reduce the unserved pool, and confirmed buying dates improve the forecast. Preserve each version so a changed SOM can be traced to account evidence or a deliberate operating choice.

Count the buildings that fit in Ground Control

The fastest way to count your serviceable building market is Ground Control by PorchRocket: select your area and trade filters, see the matching count and exact price, then order the addresses. HVAC teams can select visible rooftop units; roof crews can select roof age band and material; paving crews can select paved parking areas. Commercial buildings cost $10 to $20 each, with delivery within 48 hours after payment, often sooner. Wrong matches reported within 30 days receive a credit. These are target properties; the owners have not asked for a quote.

Start with the segment your next crew can serve. In Ground Control, build the order around these inputs and outputs:

• Properties in your chosen area and building types. Save your selection rules beside the count to preserve the market definition.
• Building-size bands and trade features, such as 2+ or 5+ visible rooftop units through the rooftop HVAC list.
• A reason each property matched, so the salesperson can start with the building’s fit instead of redoing the selection work.
• Optional owner information and decision-maker contact research, priced separately for the outreach you plan to run.
• CSV and Excel files your team can load into its sales system. Add your own buying-date and proposal columns.
• A custom request for several markets, a whole state or a detail beyond the standard filters, scoped to the territory decision.

Give the next crew a counted territory and the accounts worth pursuing.