How Much Margin Should a Custom Builder Make?

First, the obligatory line, because this one drifts near finance: I am an advisor, not your accountant. The principles below are about running a margin that keeps your business alive. The exact numbers for your business, and how they sit with your tax and your structure, are worth confirming with your own licensed professional.

Now the question every builder eventually asks me: how much margin should I actually be making? Usually it comes up after a job that should have been profitable somehow wasn't, and they are trying to work out whether the problem was the margin or the job. The honest answer is that most builders run their margin too thin, and they do not realise it because they have confused two numbers that are not the same thing.

Markup is not margin (and the difference costs you)

This trips up more builders than anything else, so let's kill it first.

Markup is what you add to your cost. Margin is what is left as a share of the price you charged.

If a job costs you a round number and you add 20 percent markup, your price is cost plus 20 percent. But that 20 percent markup is not 20 percent margin. As a share of the final price, it works out to about 16.7 percent. The bigger the gap you think you are making, the more this maths bites. A 25 percent markup is only a 20 percent margin. A 50 percent markup is only a 33 percent margin.

Builders who say "I add 20 percent" and think they are making 20 percent margin are quietly making less than they believe on every single job. Before you can decide if your margin is enough, you have to be sure you are even measuring the right number.

What margin is actually for

Margin is not the reward at the end you treat as a bonus. It has 3 real jobs:

• It absorbs the bad job. Custom builds go wrong. A subbie walks, the soil is worse than the test said, a supplier ships the wrong product 6 weeks late. Margin is the buffer that lets one rough job not wipe out the profit on the next three.
• It funds growth. The deposit on a second ute, the wage for your first leading hand, the software that finally gets you off spreadsheets, all of that comes out of margin. Run it too thin and you can never afford to grow, so you stay the bottleneck.
• It pays you for risk. You are the one carrying the can if the job goes bad, if the client disputes, if the market turns mid-build. Margin is the price of that risk, and the risk is real whether or not you charge for it.

A builder running a 5 percent net margin is one bad job away from a loss for the year. That is not a business, that is a high-stress hobby that occasionally pays.

Gross margin vs net margin

Two numbers matter and builders often only watch one.

Gross margin is what is left after the direct costs of the job: materials, subbies, site labour. It is the margin on the work itself.

Net margin is what is left after your overhead comes out too: your office, your vehicle, your insurances, your own wage, all the costs of the business existing. Net is the number that actually tells you if the business made money.

Here is the trap. You can run a healthy-looking gross margin on every job and still finish the year with nothing, because your overhead ate the gap. That happens when builders price for gross margin but forget the business itself costs money to run every single day, jobs or no jobs. Your overhead has to be carried by the gross margin across all your jobs, and what survives that is your real net margin. If you have never worked out what your overhead even is, that calculation is part of nailing your charge-out rate as a builder, because the same overhead pool feeds both.

So what is the right number

I am not going to throw out a single percentage and pretend it fits every builder, because it does not. A high-end custom builder carrying serious risk, long timelines, and fussy bespoke work needs a fatter margin than someone doing simpler, repeatable work with locked designs. The right margin depends on your risk, your overhead, and your market.

What I will say plainly is this: whatever number you land on, it has to clear your overhead and leave a genuine profit on top, and it has to be thick enough that one bad job does not turn the year red. If your current margin cannot do both of those, it is too thin, full stop. Most builders I meet are running leaner than their risk justifies, usually because they set the number years ago to win work and never revisited it.

The way to find your floor is to work backwards. Total your overhead for the year. Work out the volume of work you can realistically do. The gross margin you need on that work, just to cover overhead, is your absolute minimum before you have made a cent of profit. Your target margin sits above that line, not on it.

Defending your margin without flinching

The reason builders run thin is rarely that they don't want more. It is that they get nervous defending a bigger number to a client, so they shave it to feel competitive. The fix is not a sales script, it is conviction that comes from knowing your number is real.

When your margin is built on your actual costs and your actual risk, you can hold it in a conversation, because you are not making it up. You can show a client what they are getting for it. That conviction starts at the quote, which is why setting the margin and then quoting a custom build without underquoting go hand in hand, the quote is where a defensible margin either holds or quietly gets given away.

And margin is not just a quoting decision, it is a protect-it-every-day decision. The fattest quoted margin in the world leaks away if you do small variations for free and never charge for changes, which is why managing build variations is really a margin-protection job dressed up as paperwork.

Where margin fits in the bigger picture

Margin is one layer in the full pricing stack. It sits on top of honest costs and a sensible contract, and it cannot rescue a price where the layers underneath are wrong. That is the whole argument of the guide on pricing a custom home build: the margin is only as safe as the costing it sits on.

The practical starting point is knowing your overhead and your real costs, because you cannot set a defensible margin in a vacuum. The Charge-Out Calculator gets you the per-hour foundation for free, and from there the margin maths has something solid to stand on. If you want a straight answer on whether your current margin is actually leaving you a profit once everything is counted, the free numbers check is exactly that conversation: real figures, no guessing.