Ask ten contractors what a "25% margin" means and you'll likely get answers that describe markup instead. It's one of the most common - and most costly - mix-ups in construction quoting. Getting it wrong doesn't just mean a rounding error; it can quietly shave real percentage points off every job you price.
What markup actually means
Markup is a percentage added on top of your cost. It answers the question: "how much am I adding to what this cost me?"
Formula: Sell price = Cost x (1 + markup %)
What margin actually means
Margin is a percentage of your final sell price. It answers a different question: "of every dollar a client pays me, how much is profit?"
Formula: Sell price = Cost / (1 - margin %)
These two formulas look similar but produce different sell prices for the same target percentage - and that gap is where profit quietly disappears.
The worked example
Take a job that costs you $100 to deliver.
25% markup: Sell price = $100 x 1.25 = $125
25% margin: Sell price = $100 / 0.75 = $133.33
A 25% markup and a 25% margin are not the same thing - the margin-based price is over $8 higher on a $100 cost. Scale that up to a $50,000 job and the gap becomes thousands of dollars.
Why this trips contractors up
The mistake usually runs the other way: a contractor decides they want a 25% margin, but prices the job using a markup formula instead. Let's check what actually happens.
Using 25% markup on a $100 cost: sell price = $125.
Now check the actual margin achieved on that $125 sell price:
Margin = (Sell price - Cost) / Sell price = ($125 - $100) / $125 = 20%
So a contractor aiming for 25% margin, but calculating with a markup formula, actually delivers only 20% margin. That's a 5-percentage-point shortfall on every single job - and it compounds across a year of quotes.
Why the confusion is so costly
Margin and markup converge at low percentages and diverge more the higher they go:
| Target % | Markup sell price | Margin sell price | Difference |
|---|---|---|---|
| 10% | $110.00 | $111.11 | $1.11 |
| 25% | $125.00 | $133.33 | $8.33 |
| 40% | $140.00 | $166.67 | $26.67 |
| 50% | $150.00 | $200.00 | $50.00 |
The higher the profit percentage you're aiming for, the more expensive this mix-up becomes. Contractors chasing healthier margins on higher-value jobs are exactly the ones most exposed to the mistake.
Which one should you use?
Neither is "wrong" - they're just answering different questions, and both are legitimate ways to price work. What matters is consistency:
- Decide which one your business actually targets (most businesses that talk about "margin" as a KPI mean the margin formula, not markup)
- Use the same formula across every quote
- Make sure whoever is producing quotes - you, an estimator, or office staff - is using the same definition you are
Practical steps to protect your margin
- Write down your target margin percentage and the formula that produces it, so it's not left to memory on each quote
- Check your actual achieved margin against your target margin periodically, using completed job costs, not estimated ones
- If you're quoting from a spreadsheet, build the margin formula in as a locked calculation rather than a manual percentage add-on
- Review pricing after any cost increase - a margin formula recalculates correctly on a new cost base, but a stale markup number won't
The bottom line
Margin and markup are both valid ways to price a job, but they are not interchangeable, and using the wrong one for your target erodes profit without ever showing up as an obvious error. Know which formula you're using, apply it consistently, and check your real numbers against your target margin - not just your target markup - so the profit you plan for is the profit you actually keep.
