How to Calculate a Builder’s Margin
A builder’s margin is calculated by adding a percentage on top of the actual cost of a job — materials, labour, subcontractors and site overheads — to cover business overheads and profit. There is no single correct number: many builders work to a margin somewhere in the range of roughly 10–20% on top of cost, but the right figure for your business depends on your overheads, the size and risk of the job, and what the market will bear.
Key takeaways
- A builder’s margin is the percentage added on top of cost to cover business overheads and profit — it is not the same thing as markup, even though the two terms get used interchangeably in everyday conversation.
- There is no single correct margin: many builders work to a margin somewhere in the range of roughly 10–20% on top of cost, but the right number depends on your overheads and the specific job.
- Your margin needs to cover two distinct things — recovery of your business overheads, and genuine profit — and confusing the two usually means underpricing the job.
- Margin and markup are calculated from different bases (profit over price vs profit over cost), so the same margin figure and the same markup figure are never the same percentage.
- Getting your cost base right — accurate quantities, current rates and realistic preliminaries — matters more to your bottom line than the margin percentage you apply on top of it.
What is a builder’s margin?
A builder’s margin is the percentage added on top of the actual cost of a job — materials, labour, subcontractor quotes and site preliminaries — to arrive at the price charged to the client. It is what is left, after every real cost is paid, to cover the running costs of your business and to actually make a profit from the work.
Margin is often confused with pure profit, but the two aren’t quite the same thing. Part of your margin recovers genuine business overheads — office costs, insurances, admin wages, vehicles — that aren’t attached to any single job, and only what’s left after that is true profit. A margin that only just covers overheads, with nothing left over, isn’t really a margin at all.
There is no universal “correct” margin that applies to every builder or every job. Many builders work to a margin somewhere in the range of roughly 10–20% on top of cost, but the right number for your business depends on your overhead structure, the risk profile of the job, and current market conditions — treating any single figure as a rule rather than a starting point is one of the more common pricing mistakes in the industry.
In plain terms
Margin is what’s left on top of the real cost of a job once you’ve added your own business running costs and your profit. It isn’t a fixed number every builder should use — it’s a figure you work out for your own business and adjust for the risk of each job.
What your margin actually needs to cover
Before you can settle on a margin percentage, it helps to be clear about what it is actually paying for — because a margin that is set without accounting for all of these is a margin that will eventually come up short.
- Overhead recovery — office rent, admin and estimating wages, vehicles, insurances and other costs that exist regardless of which job is on site
- Genuine profit — the return your business earns for taking on the job, separate from simply covering costs
- Risk allowance — a buffer for the uncertainty in every job, from site conditions to price movements in materials
- Working capital — the margin also helps fund the business between being paid on this job and the next
Margin vs markup: the maths that trips people up
Margin and markup describe the same dollar profit, but they are calculated from a different base, and mixing them up is a genuinely common and costly error. Markup is profit expressed as a percentage of cost; margin is profit expressed as a percentage of the final selling price. Because the price is always larger than the cost once profit is added, a given dollar profit is always a smaller percentage as a margin than it is as a markup.
This matters in practice because a builder who means to achieve a certain margin, but actually applies that same percentage as a markup on cost, ends up with a lower margin than intended — often without realising it until the numbers are checked properly.
| Cost | Profit | Price | Markup (profit ÷ cost) | Margin (profit ÷ price) |
|---|---|---|---|---|
| $100,000 | $20,000 | $120,000 | 20.0% | 16.7% |
Working out your overhead recovery rate
Before adding a profit figure on top, most builders first work out how much of their margin needs to go simply toward recovering business overheads, so that profit isn’t quietly eaten up by costs that were never properly accounted for. The basic approach is to total your annual business overheads and divide that figure by your expected annual revenue, giving you an overhead recovery rate to apply across every job.
A business with high fixed overheads relative to its turnover needs a higher recovery rate built into its margin than a leaner operation with the same turnover — which is exactly why copying a competitor’s margin percentage, without knowing their overhead structure, tells you very little about what your own business actually needs to charge.
Setting your margin, job by job
Once your overhead recovery is accounted for, the profit component of your margin is where most of the job-by-job judgement comes in — and it’s reasonable, and common, for it to move up or down depending on the specific job in front of you.
Again, there’s no single figure that applies everywhere: many builders work to a margin somewhere in the range of roughly 10–20% on top of cost, but the right number depends on your overheads and the job — a straightforward repeat client on a well-documented scope carries a different risk profile to a first-time client on a job with incomplete drawings, and the margin can reasonably reflect that difference.
- How well-defined the scope is — vague drawings or specifications justify a higher risk allowance
- Site conditions and access, and how much genuinely can’t be confirmed until work starts
- How competitive the tender is, and whether the client is known to you or entirely new
- The size of the job — margin percentages often taper slightly on very large contracts, though in dollar terms the profit can still be substantial
- Current market conditions, including material price volatility and subcontractor availability
Where margin sits in your price build-up
Margin is the last thing added in a proper price build-up, not the first — it sits on top of an accurate cost base rather than being baked into inflated rates throughout the estimate. The build-up runs: measured quantities, priced at current rates, plus preliminaries, equals the total cost of the job; margin is then added on top of that total to reach the price quoted or tendered.
This also affects how margin applies to items priced later in the job, like provisional sums and prime cost items — most contracts state explicitly whether your margin applies to the reconciled actual cost of those items, so it’s worth checking the wording rather than assuming either way.
Common mistakes when calculating margin
Most margin problems trace back to a handful of recurring errors rather than the percentage itself being wrong.
- Confusing markup and margin, and applying the wrong one to the wrong base
- Setting margin without first working out a genuine overhead recovery rate, so profit quietly absorbs overhead costs
- Copying a competitor’s or an industry “rule of thumb” margin without accounting for your own overhead structure
- Starting from an inaccurate or incomplete cost base — margin applied on top of an under-measured quantity or an out-of-date rate still under-recovers
- Cutting margin to win a tender without adjusting the risk allowance for a genuinely riskier job
How My Trade Hub helps you protect your margin
My Trade Hub’s estimation engine gives your margin something solid to sit on top of: a measured, accurate Bill of Quantities generated directly from your plans, rather than a cost base built on rough guesses that quietly eat into whatever margin you apply.
Because every quantity and rate stays fully editable, you can apply your own margin with confidence, model it against different job risks, and see the effect on your final price immediately — all as part of an estimating workflow that runs 60-75% faster than manual estimation.
Frequently asked questions
What is a good margin for a builder?
There is no single figure that suits every builder. Many builders work to a margin somewhere in the range of roughly 10–20% on top of cost, but the right number depends on your overheads, the risk of the specific job, and current market conditions — it should be calculated for your own business rather than copied from a rule of thumb.
What is the difference between margin and markup in construction?
Markup is profit expressed as a percentage of cost; margin is the same dollar profit expressed as a percentage of the final selling price. Because price is always higher than cost, a given profit is always a smaller percentage as a margin than as a markup — mixing the two up is a common pricing mistake.
How do you calculate margin on a construction job?
Start from an accurate cost base — measured quantities priced at current rates, plus preliminaries — then add a percentage to cover your overhead recovery rate and your intended profit. Margin is that added amount expressed as a percentage of the final price, not the cost.
Does builder’s margin include GST?
Margin itself is calculated on the cost and price excluding GST, with GST then applied to the final price as required by law. Always check how your contract and any quoted figures present GST so the client understands what is and isn’t included.
Does margin apply to provisional sums and prime cost items?
It depends on the contract. Many contracts state that the builder’s margin applies to the reconciled actual cost of provisional sums and prime cost items once they are defined, but this varies by contract, so it is worth checking the specific wording rather than assuming either way.
How much margin should I add to cover my overheads?
Total your annual business overheads — office costs, admin wages, vehicles, insurances — and divide by your expected annual revenue to get an overhead recovery rate. That rate forms part of your overall margin, with your intended profit added on top of it.
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