# What Is Contribution Margin?

Contribution margin is the money a sale leaves after subtracting every cost that varies with that sale, before fixed costs. Contribution margin = Price − Variable costs; the ratio divides that by price. A $14,000 roof with $11,140 of materials, crew pay, commission and fees contributes $2,860, a 20.4% contribution margin ratio.

## Key takeaways

- Contribution margin = Price − all variable costs. Contribution margin ratio = Contribution margin ÷ Price.
- It differs from gross margin by including variable costs that sit below the gross profit line, like sales commissions, card and financing fees, and per-job fuel.
- It's the number to use for break-even math, discounts, promotions and deciding whether to take a low-priced job.
- Discounts come straight out of contribution margin, so a 10% price cut can wipe out far more than 10% of a job's contribution.
- A job with positive contribution helps pay fixed costs even if it doesn't show a profit on its own; a negative one makes things worse with every sale.

## How does contribution margin work?

Contribution margin splits your costs into two piles. Variable costs rise and fall with each job: materials, crew pay that's tied to the work, commissions, card fees. Fixed costs stay the same whether you run ten jobs or a hundred: rent, office staff, insurance, software. Contribution margin is what each job "contributes" toward fixed costs, and once they're covered, toward profit.

**Contribution margin formulas**

```
Contribution margin = Price − Variable costs   |   Contribution margin ratio = Contribution margin ÷ Price
```

Where:
- Price = what the customer pays for the job, before sales tax
- Variable costs = every cost that exists only because this job happened and grows with its size or count
- Ratio = the share of each sales dollar left to cover fixed costs and profit

> **Worked example: a roof replacement**
>
> Illustrative numbers. Price: $14,000.
>
> Variable costs: materials $5,200; crew paid per square $3,800; dumpster and permit $600; sales rep commission at 8% of price $1,120; card or financing fee at 3% $420. Total: **$11,140**.
>
> Contribution margin = $14,000 − $11,140 = **$2,860**. Ratio = $2,860 ÷ $14,000 = **20.4%**.
>
> The same roof shows a 31.4% [gross margin](https://www.brix.so/learn/gross-margin), because commission and fees aren't in cost of goods sold. The 11-point gap is real money that never reaches overhead.

## What's the difference between contribution margin and gross margin?

Gross margin subtracts cost of goods sold, which follows accounting rules about what's a direct job cost. Contribution margin subtracts every variable cost, wherever it sits on the profit and loss statement, and leaves out fixed costs even if they're in COGS. The two often look similar, but they answer different questions.

**Which costs each margin subtracts**

| Cost | Gross margin | Contribution margin |
| --- | --- | --- |
| Materials and parts | Subtracted | Subtracted |
| Crew pay tied to the job (per job, per square, piece rate) | Subtracted | Subtracted |
| Hourly techs paid a full week regardless of volume | Subtracted | Often treated as fixed in the short run |
| Subcontractors, permits, dumpsters | Subtracted | Subtracted |
| Sales commissions and tech spiffs | Usually not (they sit in overhead or selling expense) | Subtracted |
| Card processing and customer financing fees | Usually not | Subtracted |
| Fuel and mileage per job | Usually not | Subtracted if you track it per job |
| Rent, office staff, insurance, software | Not subtracted | Not subtracted (fixed) |

_Where commissions and fees land depends on your chart of accounts. The point is that contribution margin catches them all._

Use gross margin to read your [profit and loss statement](https://www.brix.so/learn/profit-and-loss-statement) and set prices against direct costs. Use contribution margin for decisions about volume: [break-even](https://www.brix.so/learn/break-even-point), discounts, promotions and whether a low-priced job is worth taking.

## How does a discount affect contribution margin?

A discount comes almost entirely out of contribution margin, because materials and crew pay don't shrink when the price does. That's why a small percentage off the price can cut a job's contribution nearly in half, and why you need far more jobs to make up for it.

> **Worked example: 10% off the same roof**
>
> Illustrative numbers. Price drops to $12,600. Materials, crew pay, dumpster and permit stay at $9,600. Commission (8%) falls to $1,008 and the fee (3%) to $378.
>
> Contribution margin = $12,600 − $9,600 − $1,008 − $378 = **$1,614**, down from $2,860.
>
> A 10% discount cut the job's contribution by **43.6%**. To earn the same total contribution, you'd need about 1.77 times as many roofs: **77% more jobs**.

Before discounting, offer a smaller scope instead. [Good-better-best pricing](https://www.brix.so/learn/good-better-best-pricing) lets a price-sensitive customer choose a lower option without you cutting the margin on the same work.

## Is a loss-leader promotion worth it?

A promotion is worth it only if the follow-on work it brings in adds more contribution than the promotion gives away. Work out the contribution on the promo itself, then estimate how many promo customers buy something else.

> **Worked example: a $79 tune-up special**
>
> Illustrative numbers. An HVAC company offers a $79 tune-up. Variable costs: 1.25 hours of burdened tech time at $42 ($52.50), filters and supplies $6, and a 3% card fee ($2.37).
>
> Contribution per tune-up = $79 − $52.50 − $6 − $2.37 = **$18.13**. Barely positive, before the cost of the ads that sold it.
>
> The promo pays off only through what comes next: repairs found during the visit, a [maintenance agreement](https://www.brix.so/learn/maintenance-agreement), or a replacement lead. Track those per promo customer, or the special just keeps techs busy at close to zero.

## Contribution margin by trade

The variable costs that separate contribution margin from gross margin are different in each trade. These are the ones worth tracking per job.

**Variable costs that gross margin often misses, by trade**

| Trade | Variable costs to include | Decision it helps with |
| --- | --- | --- |
| HVAC | Comfort advisor commissions, tech spiffs, customer financing fees on replacements | Whether to offer 0% financing promos and how much to discount a system |
| Plumbing | Tech commission on sold work, card fees, after-hours premium pay | Whether to drop the trip fee or after-hours charge |
| Electrical | Permit and inspection fees per job, card fees | Minimum charge for small service calls |
| Roofing | Sales rep commission, financing fees, per-square crew pay | How far a rep can negotiate on price |
| Landscaping | Fuel and dump fees per visit, per-visit crew pay | Whether to add a far-away account to a route |
| Cleaning | Per-visit cleaner pay, supplies, drive time between homes | Whether to accept one-off deep cleans at a discount |

## Common contribution margin mistakes

- **Leaving out commissions and fees.** They're invisible in gross margin but come off every sale.
- **Calling fixed costs variable.** If a cost doesn't go away when the job doesn't happen, it's fixed. Spreading rent per job hides that.
- **Judging a promotion by revenue.** A busy month of $79 tune-ups can bring in a lot of revenue and almost no contribution.
- **Discounting without the math.** Calculate how many extra jobs a discount needs before you offer it.
- **Using one ratio for every job type.** Repairs, installs and maintenance visits carry very different contribution margins. Track them separately with [job costing](https://www.brix.so/learn/job-costing).

BRIX builds quotes on site from your price list and follows up every open estimate by text and email, so you can win more jobs at full price instead of reaching for a discount to close.

- [Quotes and estimates](https://www.brix.so/features/quotes-estimates): Builds accurate quotes on site and follows up on every open estimate.
- [Sales automation](https://www.brix.so/features/sales-automation): Follows up every lead and open estimate automatically by text and email, and asks every customer for a review after the job.

## Frequently asked questions

### How do you calculate contribution margin?

Subtract every variable cost of a sale from its price. For a $14,000 roof with $11,140 of materials, crew pay, dumpster, commission and fees, contribution margin is $2,860. Divide by the price to get the ratio: 20.4%.

### What is the difference between contribution margin and gross margin?

Gross margin subtracts cost of goods sold. Contribution margin subtracts all variable costs, including commissions, card fees and financing costs that usually sit below the gross profit line, and excludes fixed costs. Use gross margin for financial statements and contribution margin for volume and pricing decisions.

### What is a good contribution margin ratio?

One that, multiplied by your revenue, covers fixed costs plus the profit you want. If fixed costs are $30,000 a month and you expect $80,000 of revenue, you need at least a 37.5% ratio to break even. There's no universal target because cost structures differ so much between trades.

### Can contribution margin be negative?

Yes. If variable costs are higher than the price, every sale loses money before fixed costs are even counted. Deep discounts, underpriced promotions and jobs that run far over the estimated hours are the usual causes.

### Is labor a variable cost?

It depends on how you pay. Crew paid per job, per square or by piece rate is variable. Hourly techs paid for a full week no matter what act like a fixed cost in the short run, because you pay them whether or not the job happens. Overtime is variable.

### How is contribution margin used in break-even analysis?

Break-even jobs equal fixed costs divided by contribution margin per job. Break-even revenue equals fixed costs divided by the contribution margin ratio. A higher contribution per job means fewer jobs are needed to cover fixed costs.

## Related

- [What Is a Break-Even Point?](https://www.brix.so/learn/break-even-point)
- [What Is Gross Margin?](https://www.brix.so/learn/gross-margin)
- [What Is Net Profit Margin?](https://www.brix.so/learn/net-profit-margin)
- [What Is Good-Better-Best Pricing?](https://www.brix.so/learn/good-better-best-pricing)
- [Markup vs. Margin: What's the Difference?](https://www.brix.so/learn/markup-vs-margin)
- [What Is Job Costing?](https://www.brix.so/learn/job-costing)
- [Break-Even Calculator for Service Businesses](https://www.brix.so/tools/break-even-calculator)
- [Markup and Margin Calculator](https://www.brix.so/tools/markup-margin-calculator)
- [How to Price Contracting Jobs for Profit: The Complete Guide](https://www.brix.so/guides/how-to-price-jobs)
- [Maintenance Agreement Pricing Calculator](https://www.brix.so/tools/maintenance-agreement-calculator)

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Written by BRIX Editorial Team. Last updated 2026-10-12.
Canonical: https://www.brix.so/learn/contribution-margin