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How much should an HVAC company spend on marketing? Start from trucks and tickets, not a percent of revenue

A percent of last year's revenue spends the most in the month the board is already full. How to size the budget from open truck slots, check it against what a sold job is worth, and enter it in Google Ads without the weekday-schedule trap.

By Lonta AIPublished Updated 13 min readHow we write

TL;DR

  • No percentage gives you the right HVAC marketing budget. Count the service calls your trucks can run in a month, subtract what fills the board without ads, and buy the rest at your own cost per booked call. In the illustration below, a five-truck shop can use about $10,500 of ads in July and up to $26,400 in October, the reverse of what 8% of each month's revenue gives it.
  • Check that number against the most a sold job is worth paying for, and against whether your market has that many searches.
  • In Google Ads, divide the monthly number by 30.4. Google paces to the full 30.4 days even if your ads run weekdays only. Divide by 22 working days and Google paces the month to about 38% more than you planned.
  • On Maximize conversions, expect Google to try to spend the whole daily budget: Google says the strategy "will try to fully spend your average daily budget".
  • Both SBA percentages the budget guides quote, 3–5% and 7–8%, appear in a 2012 contributor post on the SBA blog, since taken down. The SBA blog's 2019 post says "There's no hard and fast answer". Neither post is about HVAC.

Why a percent of revenue is the wrong start for an HVAC marketing budget

A percent of revenue ties this year's budget to what you billed last year, and a service shop's billing is capped by its trucks. So a budget set from revenue comes out highest in the months the board was fullest and lowest in the months it had the most room. In July the phone rings anyway: members, repeat customers, referrals, people who read the number off a truck. Paid calls fill the gap between that and what the trucks can run. In the accounts we run, that gap is smallest in peak season and largest in the shoulder months.

The budget guides we read for this question answer with a share of revenue. Hook Agency's budget guide calls 7–10% of annual revenue "the general rule of thumb" for small-to-midsize HVAC companies. Digital Harvest puts shops under $1 million at 5–10% of gross revenue and says the "SBA guideline of 3% to 5%" often falls short for startup-stage HVAC companies. Chron's small-business section credits the SBA with 7 to 8 percent.

Both SBA numbers appear in a 2012 contributor post on the SBA blog, now removed from sba.gov and kept in the Internet Archive: 2–3% of revenue for ongoing marketing, up to 3–5% for start-up marketing and, "as a general rule", 7–8% for small businesses under $5 million in revenue with margins of 10–12% (see the home services marketing statistics we traced to their sources). The SBA blog's 2019 post on marketing budgets says "There's no hard and fast answer to how much your marketing budget should be" and suggests asking your trade association. Neither post is about HVAC. A percentage is a fair check on the yearly total. It can't tell you which month to spend it in.

How many service calls can your trucks run?

  1. Capacity. Service trucks on the road × calls each tech runs in a day × working days. Use a normal busy day from the dispatch board, not a record.
  2. What fills the board without ads. From your CRM, count last year's calls in the same month from members, repeat customers, referrals, the number on the truck and warranty callbacks: anything not from paid ads.
  3. Open slots. Capacity minus step 2: the booked visits the ads need to produce.
  4. Ad calls needed. Open slots ÷ the share of ad calls that ended with a visit on the board, from call tracking for the same month last year. Count the calls nobody picked up in that share (answer rate and booking rate explains why).
  5. Spend. Ad calls needed × your cost per ad call, same month last year.

That is the budget the trucks can use, before the two checks below.

A worked example: one shop, July and October

These numbers are an illustration, not client data. Put your own in their place.

A shop runs five service trucks. Each tech runs four calls a day, 22 working days a month: 440 service calls. Seven in ten visits end in a sold job, and the average ticket is $600, so the most these trucks can bill from service calls in a month is 440 × 0.7 × $600 = $184,800.

JulyOctober
Service calls the trucks can run440440
On the board without paid ads370200
Open slots for ads to fill70240
Ad calls that end with a visit on the board50%50%
Ad calls needed140480
Cost per ad call, same month last year$75$55
Spend the trucks can use$10,500$26,400
Cost per sold job ($ per call ÷ 0.5 ÷ 0.7)$214$157

Now the same shop at 8% of each month's revenue last year, again as an illustration. Last July the board was full: $184,800 billed, so $14,800 of ads. Last October it ran about 300 calls: 300 × 0.7 × $600 = $126,000, so $10,100.

In July the percent budget spends $4,300 more than the trucks can use: at $75 a call, about 57 extra calls and, at a 50% booking share, about 29 visits with no truck free to run them. In October it spends $16,300 less than the open slots could use.

Is a sold job worth what you're paying for it?

Capacity says how many calls the trucks can use, not whether they're worth buying. Write down the most you'll pay for a sold job before you open the account.

Our reading is to set that ceiling from the gross profit on an average service ticket. In the illustration, a $600 ticket at a 50% gross margin leaves $300. At $300 a sold job only breaks even on gross profit, so that is the limit, not the target. July's $214 and October's $157 both sit under it. If a heat wave pushed July's cost per ad call from $75 to $110, cost per sold job would reach $314 ($110 ÷ 0.5 ÷ 0.7), and the right July budget would be smaller than the open slots.

We leave replacements and memberships out of that ceiling on purpose: they are real, and they are the easiest numbers to stretch when someone wants a bigger budget. The formula under the table is explained in cost per lead vs cost per sold job.

Can your market supply that many calls?

A budget can only buy searches that happen. Our read is that repair searches fall off in the shoulder months just as the open slots grow. Which Google Ads check tells you whether more money buys more calls depends on the bid strategy.

  • Maximize conversions. Google recommends "tools such as budget simulator and impression share metrics" for this strategy, but not the "Lost IS (budget)" column: the strategy is designed to spend the full daily budget and is "limited by budget" by design.
  • Target CPA, Maximize clicks or manual CPC. Add "Search lost IS (budget)", which Google defines as "the percentage of time that your ads weren't shown on the Search Network due to insufficient budget" (campaign level only). Google's warning names only Maximize conversions and Maximize conversion value; using the column on Target CPA or Maximize clicks is our read. So is this: near zero means budget wasn't what kept your ads off those searches, and more money alone buys few extra calls. Losses to Ad Rank show in "Search lost IS (rank)".

Google also shows a recommended budget for campaigns that "repeatedly meet their average daily budget but have the potential to earn more clicks and impressions." Our reading: that number is sized to the clicks available, not to your board.

When October's open slots are bigger than search can fill, the rest has to come from selling what people buy in October: tune-ups and plans to your own customer list, replacement offers, work that doesn't depend on the weather (what to sell when the season turns, advertising maintenance plans). Or you leave some slots open, which costs less than calls bought over your ceiling.

How much should an HVAC company spend on Google Ads per month?

The spend from step 5 above, once it passes the two checks. If you run more than one paid channel, give each its share of the open slots and work out steps 4–5 for each with its own booking share and cost per call. Then enter the Google Ads number the way Google reads it.

Monthly to daily: divide by 30.4. Google's help page divides a monthly amount by 30.4, "the average number of days in a month", to get the average daily budget. For most campaigns you'll never pay more than 2 × the daily budget on a day, or 30.4 × it in a month. July's $10,500 is $345 a day.

The weekday trap. Many shops run ads only while the office answers. Google's page on spending limits says that with ad scheduling the monthly limit stays 30.4 × the daily budget, and "the system will pace to reach this full monthly limit regardless of how many days the campaign is scheduled to be active." Divide July's $10,500 by 22 working days and you set $477 a day. Google paces to $477 × 30.4, about $14,500: $4,000 over plan, in the month the trucks have the least room.

Maximize conversions tries to spend all of it. Google says the strategy "will try to fully spend your average daily budget", so if you spend much less than your budget today, switching to it "could increase spend significantly." With a Target CPA, the aim is your average cost per conversion "rather than spending your full budget".

Changing it mid-month. After a change, Google says spend for the rest of the month "won't exceed your new average daily budget multiplied by the remaining number of calendar days in the month".

Local Services Ads. When your account moves into Google Ads, Google divides your historical average weekly budget by 7 to set a daily average budget, with the same 30.4 monthly cap (what else changes in the move). You still pay per lead, and after the move Google says you can pause the campaign to stop leads at any time.

Full trucks and idle ones: two accounts we run

Tampa. The Comfort Authority fixes air conditioning and plumbing from one shop in Tampa. Cooling runs most of the year there, and the crew is at capacity from May to September, so the ceiling on that account is the calendar, not the budget. Past a point, more July calls aren't worth buying. The work went into which calls instead: calls wired through to the CRM first, the radius rebuilt on drive time instead of the forty-seven cities on the service area page, and search terms that never become jobs cut.

The Comfort Authority · Tampa, FLRead the case
−22%
Calls from ads
Window
90 days against the 90 before
Source
Call tracking

The Comfort Authority, Tampa Bay. Calls from ads: −22%. Window: 90 days against the 90 before. Source: Call tracking.

Limit: We cut the far cities. We did not prove they are unprofitable at every budget — only that they were unprofitable at this one, against the near ones.

The Comfort Authority · Tampa, FLRead the case
1.6×
Jobs sold from paid search
Window
90 days against the 90 before
Source
Client CRM

Same account. Jobs sold from paid search: 1.6×. Window: 90 days against the 90 before. Source: Client CRM.

Limit: Jobs sold come from the client's CRM, which means they depend on technicians closing tickets correctly. We did not audit that, we read it.

Phoenix. Way Cool sells plumbing, air conditioning and home performance. From late November, cooling demand in Phoenix drops close to nothing for four months while the crews stay on payroll, and the account had been cutting the budget in those months. Instead, the winter money went to the whole-home audit already on the website: search on audit and insulation terms, paid social to neighborhoods with the right housing stock, and cooling search kept narrow.

Way Cool Plumbing & Air · Phoenix, AZRead the case
2.3 to 2.5×
Audits booked in the off-season
Window
December–February against the year before
Source
Client CRM

Way Cool, Phoenix. Audits booked in the off-season: 2.3 to 2.5×. Window: December–February against the year before. Source: Client CRM.

Limit: We doubled off-season spend. A doubling from a small base is an easier decision than it sounds, and this does not demonstrate the same return at a serious winter budget.

What this doesn't cover

Do this in your account

  1. Count capacity for the next three months: service trucks × calls per tech per day × working days.
  2. Pull the same months last year from your CRM by lead source. Capacity minus everything not from paid ads is your open slots.
  3. Pull the same months from call tracking: calls from ads, the share that ended with a visit on the board, and cost per call.
  4. Work out the spend the trucks can use and the cost per sold job, and compare it with the ceiling you wrote down first.
  5. Check the market: the budget simulator and impression share on Maximize conversions, "Search lost IS (budget)" on other strategies.
  6. Set the daily budget at the monthly number ÷ 30.4, even if the ads run weekdays only. Hover over the campaign's budget in the Budget column and click View budget report to see the monthly limit and forecast. The report doesn't work for Performance Max, and Google notes that ad schedules aren't reflected in its forecast.
  7. When the board is booked out, lower the budget, and raise it when slots open. The rest of the month re-paces to the new number.

FAQ

How much should an HVAC company spend on Google Ads per month? Enough to fill the service slots your trucks have open, at a cost per sold job you can afford, and no more than your market's searches can supply. The number comes from your own capacity, booking share and cost per call.

What percentage of revenue should an HVAC company spend on marketing? The HVAC guides we read say 5–10% or 7–10% of revenue; the section on percentages above shows where the SBA figures come from. Use a percentage to check the yearly total, not to set a month.

Why did Google spend more than my daily budget? For most campaigns Google can spend up to twice the average daily budget on a single day. Over a calendar month you won't pay more than 30.4 times it, as long as the budget stays the same all month; a change mid-month resets the cap to what you've spent plus the new budget times the calendar days left.

Should I cut the ad budget in the slow season? Cut what goes to searches that have dried up, but the open slots are largest then. Our reading is that the money should move to what people buy in those months, starting with your own customers, rather than disappear. HVAC slow season covers what to sell.

Sources

All read in full on September 24, 2026. Every quotation above is from these pages.

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