What is the difference between contribution margin and gross margin?

Contribution margin deducts only the costs that vary with sales. Gross margin deducts cost of sales as the accounts define it, which for a manufacturer includes fixed production overheads such as factory rent and plant depreciation. Two businesses with the same gross margin can therefore lose very different amounts of profit in a downturn. Gross margin comes from the statutory accounts; contribution margin usually has to be built from the management accounts.

How do you calculate breakeven using contribution margin?

Divide fixed costs by the contribution margin ratio. A business with fixed costs of US$3m and a contribution margin of 25% breaks even at revenue of US$12m, because each dollar of sales contributes 25 cents towards the fixed costs. For breakeven in units, divide fixed costs by the contribution per unit instead. A lender often adds debt service to the fixed costs to find the revenue at which the business can still pay the bank.

Is labour a variable cost?

It depends on the contracts, not the job title. Casual, piece-rate and agency workers who are paid only when there is work behave as variable costs. Permanent staff on salaries are fixed until the business decides to reduce them, and redundancy carries its own cost and notice periods. Many businesses have both, so a lender asks for the headcount by contract type before it accepts a split that treats all production labour as variable.

What does a high contribution margin mean for a lender?

It means each dollar of extra sales adds a lot of profit and each dollar of lost sales takes a lot away. A software business with few variable costs has a high margin and can see profit swing sharply with revenue; a distributor with a thin margin loses little profit per lost dollar of volume, but a small cut in its prices can take all of it. The margin is read with the breakeven and the margin of safety, not alone.

// WORKED EXAMPLETHE ARITHMETIC A DECISION RESTS ON

Contribution Margin: a Worked Example

Which costs leave with the customer, and which stay behind?

BY MICHAEL SHANG · SIXTEEN YEARS IN COMMERCIAL BANKING · UPDATED 2026-11-07 · 5 MIN READ

// THE SHORT ANSWER

A lender uses contribution margin to answer one question about a downturn: how much profit goes with each dollar of lost sales? It sorts a borrower's costs into those that rise and fall with sales and those that do not, and what is left of revenue after the first group is the contribution towards the second. From that comes the breakeven level of sales and the size of the fall the business can absorb before it stops covering its debt service. The answer depends almost entirely on how the costs are sorted, which is where a lender spends its time.

BASIS Practitioner judgment from sixteen years in commercial banking, set out in How Bankers Think (Highbank Press, 2026). Every borrower on this site is a composite constructed for teaching, not a client. The market is mid-market commercial lending as practised in New Zealand and Australia; where a convention differs elsewhere, the page says so.

// WORK THE SUM

Every Groundwork file that is a number to work out — cash conversion, debt service cover, expected loss, risk-weighted assets, the margin on a bank's own book — with the working shown in the senior read. One minute each, no signup.

Open The Number →

PART OF Credit Analysis for Beginners

// 01 — WHY A LENDER SORTS COSTS BY BEHAVIOUR

An income statement arranges costs by what they are or by which function incurred them. Under IFRS, under the UK's FRS 102 and in the special-purpose accounts many smaller New Zealand and Australian companies prepare, nothing requires a business to say which of its costs would fall if its sales fell. That is the question a lender has about any downturn, because the costs that stay are the ones that turn a fall in sales into a loss and a loss into a missed repayment.

So the lender rebuilds the cost base from the management accounts. Materials bought for each order, freight paid per load and commission paid per sale go with the revenue. Rent, salaried staff, insurance and most overheads stay. The result is a short table a credit paper can carry, and the base for every sensitivity the lender runs on the borrower's forecast.

// 02 — HOW THE FIGURES ARE CALCULATED

Contribution = revenue − variable costs

Contribution margin = contribution ÷ revenue

Breakeven revenue = fixed costs ÷ contribution margin

Margin of safety = (revenue − breakeven revenue) ÷ revenue

Profit lost per $1 of lost volume = contribution margin

The formulas hold only inside the range of activity where the sorting is true. Some costs are part fixed and part variable, such as a delivery fleet that runs whatever the load, and are split before the arithmetic starts. Some fixed costs step: a second shift is fixed until it is cut, then it is gone. And a business selling many products has a blended margin that moves with its mix, which is why a lender reads it beside a price-volume-mix analysis.

// 03 — THE EXAMPLE

A maker of timber pallets, constructed for this page like every figure in it, has revenue of US$20.0m and EBITDA of US$2.0m. Its management accounts treat timber (US$9.0m), freight (US$1.4m), nails and consumables (US$0.6m) and production wages (US$3.0m) as variable, and US$4.0m of overheads as fixed. The production staff are permanent crews on salaried contracts. Debt service is US$1.0m a year. Figures are in US$m.

Management's split Lender's split

Variable costs 14.0 11.0 (wages moved)

Contribution 6.0 9.0

Contribution margin 30% 45%

Fixed costs 4.0 7.0

EBITDA 2.0 2.0

Breakeven revenue 4.0 ÷ 0.30 = 13.3 7.0 ÷ 0.45 = 15.6

Margin of safety 33% 22%

Revenue falls 15%, to 17.0:

Management: 17.0 × 0.30 − 4.0 = 1.10 cover 1.10×

Lender: 17.0 × 0.45 − 7.0 = 0.65 cover 0.65×

Both splits give the same EBITDA today; they disagree about tomorrow. If the crews really go home when orders fall, a 15% fall leaves the pallet maker covering its debt service. If they stay on the payroll, as permanent staff usually do while notice, consultation and redundancy run their course, the same fall leaves it short. A lender that cannot tell which is true runs both. The figures are the example's, not a market norm.

// 04 — HOW IT DIFFERS FROM GROSS MARGIN

Gross margin is revenue less cost of sales, and for a manufacturer cost of sales is built on absorption costing. IAS 2, as adopted in all three markets, and the inventories section of FRS 102 both require fixed production overheads, allocated on normal capacity, to be included in the cost of stock. Factory rent, plant depreciation and supervisors' salaries can therefore sit in cost of sales, so a gross margin mixes fixed costs with variable ones. It can also move with stock levels: a business that produces more than it sells carries some of its fixed overheads into the balance sheet. Contribution margin removes both effects.

It also differs from operating leverage, which describes how much of a cost base is fixed. Contribution margin is the arithmetic that measures its effect: contribution divided by EBITDA gives the percentage change in profit for each 1% change in volume, here 6.0 ÷ 2.0 = 3 times on management's split and 9.0 ÷ 2.0 = 4.5 times on the lender's.

DEFINED IN ONE PARAGRAPH → · OPERATING LEVERAGE → · HOW BANKS TEST BORROWER FORECASTS →

// 05 — WHERE IT DECIDES A FILE

It decides the downside case. A lender's stress test is usually a fall in sales, and contribution margin converts that fall into lost EBITDA and lost cover. It also separates two kinds of fall that a revenue line treats alike. On the lender's split, a 5% cut in the pallet maker's prices takes US$1.0m off EBITDA, because every dollar of a price cut comes off profit; a 5% fall in volume takes US$0.45m, because the timber is not bought either. A borrower facing a price war is in a worse position than one losing the same revenue in volume, and the credit paper says which.

HOW BANKS READ MANUFACTURING → · PRICE-VOLUME-MIX ANALYSIS →

// SOURCES

The documents the statements on this page rest on. Each was opened and checked when cited.

Australian Accounting Standards Board, AASB 102 Inventories (compiled, 31 December 2021), the Australian text of IAS 2 — paragraphs 12 and 13 — Requires costs of conversion to include a systematic allocation of fixed and variable production overheads, with fixed overheads allocated on the normal capacity of the production facilities — section 04.
HM Revenue & Customs, Business Income Manual, BIM33135 — Stock: valuation: lower of cost and net realisable value: cost — Records that FRS 102 Section 13 classifies production overheads as fixed or variable and that fixed production overheads are allocated to the cost of stock on the basis of normal capacity — section 04.

// QUESTIONS PEOPLE ASK

What is the difference between contribution margin and gross margin?: Contribution margin deducts only the costs that vary with sales. Gross margin deducts cost of sales as the accounts define it, which for a manufacturer includes fixed production overheads such as factory rent and plant depreciation. Two businesses with the same gross margin can therefore lose very different amounts of profit in a downturn. Gross margin comes from the statutory accounts; contribution margin usually has to be built from the management accounts.
How do you calculate breakeven using contribution margin?: Divide fixed costs by the contribution margin ratio. A business with fixed costs of US$3m and a contribution margin of 25% breaks even at revenue of US$12m, because each dollar of sales contributes 25 cents towards the fixed costs. For breakeven in units, divide fixed costs by the contribution per unit instead. A lender often adds debt service to the fixed costs to find the revenue at which the business can still pay the bank.
Is labour a variable cost?: It depends on the contracts, not the job title. Casual, piece-rate and agency workers who are paid only when there is work behave as variable costs. Permanent staff on salaries are fixed until the business decides to reduce them, and redundancy carries its own cost and notice periods. Many businesses have both, so a lender asks for the headcount by contract type before it accepts a split that treats all production labour as variable.
What does a high contribution margin mean for a lender?: It means each dollar of extra sales adds a lot of profit and each dollar of lost sales takes a lot away. A software business with few variable costs has a high margin and can see profit swing sharply with revenue; a distributor with a thin margin loses little profit per lost dollar of volume, but a small cut in its prices can take all of it. The margin is read with the breakeven and the margin of safety, not alone.

// NEXT TO IT

// ON WHOSE DESK

The seats that read this term in an ordinary week. Each page says what the seat is for, who arrives in it, and the shape of the round it runs.

Credit analystReads a borrower and writes the recommendation a decision-maker will act on.
Credit sanctionerHolds delegated authority and signs — or declines — the lending the front line brings.
Portfolio managerOwns the credit on a book after the money is out — reviews, covenants, ratings and early warning.

THE IN-TRAY · ONE MINUTE

Make the call on one file.

A short file on the ground this page covers. Every option opens with how far it sits from a senior banker’s read.

THE FIRST QUESTION · THE LOAN · CAPACITY

Two borrowers each carry debt of three times EBITDA. One sells software on three-year contracts; the other builds new houses for sale.

Is three times the same risk for both?

5 MORE ON THE LOAN · CAPACITY →WHERE DO YOU READ FROM? THE PLACEMENT →

THE READING ROOMIN ONE PARAGRAPHContribution margin What is contribution margin, and how does a lender use it to find breakeven?