Divisor vs Multiplier: How HVAC Contractors Underprice Every Job

Most new HVAC business owners can size a system, pull a permit, and make a clean install look easy. Then they price the job by feel, or by a multiplier somebody taught them years ago, and wonder why a full schedule never turns into a full bank account.

The 2025 ACCA Contractor of the Future Study, built on responses from more than 1,000 contractors, put a number on it: the median HVAC contractor runs a net profit margin of about 5.8%, while the top quartile clears 13.2%.³ The difference is rarely talent in the field. It is pricing discipline, and most of it comes down to one piece of math that almost everyone gets backwards.

Markup and margin are not the same number

Two terms first, because mixing them up is the whole problem. Cost of goods sold (COGS) is what the job costs you to deliver: equipment, materials, and the labor to install it. Gross margin is the profit left after COGS, stated as a percentage of the price you charge. Markup is the amount you add on top of cost, stated as a percentage of the cost.

Here is the trap. Markup is measured against cost. Margin is measured against the selling price. Those are different denominators, so the same percentage gives you two different answers. A 30% markup does not produce a 30% margin. It produces a 23% margin. Every time you add a percentage to your cost and assume that is your profit margin, you are charging less than you think.

The worked example: a $10,000 job, two answers

Say a replacement install costs you $10,000 all in. You want a 30% gross margin to cover overhead and leave real profit.

The multiplier way, which is how most shops do it: multiply cost by 1.30. That gives a price of $13,000 and $3,000 of gross profit. Feels like 30%. Divide that $3,000 of profit by the $13,000 you actually charged, and your true margin is 23.1%. You just gave away seven points of margin and never saw it leave.

The divisor way: divide cost by one minus your target margin. One minus 0.30 is 0.70, so $10,000 divided by 0.70 is $14,286. Gross profit is $4,286, and divide that by the $14,286 price and you land on exactly 30%. The divisor forces the price to contain the margin you actually want.

The difference is $1,286 on a single job. Run 100 installs in a year and that one habit is worth about $128,000, almost all of which drops straight to the bottom line. In a tighter scenario, where your overhead alone eats 34% of revenue, the multiplier job can finish at a net loss while the divisor job still hits your target. Busy all summer, broke by fall.

If this sounds like the trap behind every shop that is busy but broke on $150 service calls, it is the same disease in a bigger dollar amount.

Garbage in: the fully loaded labor problem

The divisor method is only as good as the cost you feed it, and labor is where the cost goes wrong. A technician who earns $35 an hour does not cost you $35 an hour. Once you add the employer share of payroll taxes, workers’ compensation (higher in the trades than almost anywhere else), health and retirement contributions, paid time off, training, and the truck, the real number lands a lot higher. The labor burden in the trades typically runs 1.25 to 1.50 times the base wage, so that $35 tech costs you somewhere around $44 to $53 for every productive hour.²

Then there is the time you never bill at all: driving between calls, running to the supply house, the morning meeting, loading the truck. If you divide a tech’s full annual cost only by the hours you actually invoice, the true cost per billable hour climbs higher still. Price a job off the base wage and you leave that entire gap on the table on every hour of the install. Get the loaded rate right and the divisor finally has something honest to work with.

Service is different: why flat rate wins there

Installs want the divisor. Service wants flat rate, and the same study backs it up: contractors using flat-rate pricing on service report about 7% net profit, versus 4% for those still billing by the hour.¹ ⁴ Flat rate means you charge for the repair, not the clock. The customer sees the price before you start, which kills the sticker-shock argument, and your fast technician stops getting punished for being fast.

The honest objection is that flat rate ignores job difficulty. A coil swap in a roomy mechanical closet and the same coil in an 18-inch crawlspace are not the same job. Good flat-rate systems handle that with difficulty adders for attic access, tight clearance, or ancient equipment, so the base price covers the normal case and the exceptions are visible instead of buried in a timesheet fight. None of this is about charging more for its own sake. It is about pricing at a number that reflects the work instead of a number you hope covers it.

Put it in a price book, not your head

The reason this math fails in practice is that it lives in people’s heads. About 56% of contractors now run field service management (FSM) software, but most use it as a glorified invoicing tool and never touch the built-in price book.¹ A documented, locked price book is where the divisor and the loaded labor rate stop being good intentions and become the only price a technician can quote. It updates equipment costs, applies your target margin automatically, and removes the option to underbid on a hunch.

That is also why software alone does not fix it. The number has to be right before you lock it in, which is why the price book and the bookkeeping have to come together, and why the discipline has to exist before the tool does any good.

Start this week with three moves. Calculate your real labor burden so you know your loaded cost per billable hour. Set a target gross margin for installs and a separate one for service. Then build the divisor and flat-rate numbers into a price book and lock it, so the math protects you on every job instead of only the ones you slow down to think about. None of it requires selling anything a customer does not need. It just means getting paid correctly for the work you already do well.

This one came out of a conversation on the HVAC Know It All Business Edition Podcast with TJ O’Connor of Farmington Consulting Group, who walked through the Contractor of the Future findings on pricing and profitability.