Break-Even Analysis: A Plain-English Guide for Small Businesses

Break-even analysis answers one blunt question: how much do you have to sell before the business stops losing money? Below that point you are funding the business out of reserves; above it, every extra sale contributes to profit. The maths is short and stable, but the answer turns a vague worry about whether the numbers work into a single concrete target you can plan a quarter around. Our break-even calculator does the arithmetic in your browser; this guide explains what sits underneath it, where people get it wrong, and how to use the figure once you have it.

Fixed vs variable costs (and the trap)

Every cost in your business falls into one of two buckets for this purpose.

Fixed costs stay the same regardless of how much you sell over the period. Rent, salaried staff, your accountant, software subscriptions, insurance, the broadband bill. Sell nothing or sell a thousand units this quarter — the rent is identical. Variable costs move with each unit sold: materials, packaging, postage, card-processing fees, the wholesale price of stock, the per-order courier charge. No sales, no variable cost; double the sales, roughly double it.

The trap is misclassification, and it goes both ways. People label delivery as fixed because "we always pay for delivery" — but if it is charged per parcel it is variable and belongs in the per-unit figure. Conversely, a flat-fee marketing retainer gets pushed into variable costs because it relates to sales, when it does not change with volume and is therefore fixed. Two grey cases worth deciding deliberately: payment-processing fees are variable (they scale per transaction), and your own pay is fixed if you genuinely need to draw it to keep going. Getting these the wrong way round does not nudge the answer — it can move the break-even point by hundreds of units, because the two costs enter the formula in completely different places.

The contribution-margin method

The standard approach is the contribution-margin method, the same one taught in management accounting. It rests on a single idea: each sale, after you have paid the variable cost of that sale, leaves a slice of money behind. That slice is the contribution per unit, and it is what chips away at your fixed costs.

Contribution per unit = selling price − variable cost per unit

Stack up enough of those slices and the fixed costs are fully covered. The point at which that happens is break-even:

Break-even (units) = total fixed costs ÷ contribution per unit

Break-even (revenue) = break-even units × selling price

One honest edge case: if the contribution per unit is zero or negative, there is no break-even point at any volume. Selling more simply loses more, and the fix is your price or your variable cost, not your sales effort. A trustworthy tool should say so plainly rather than print a confident but meaningless number.

A worked example

Suppose fixed costs for the quarter — rent, your own modest drawings, software, insurance — total £5,000. You sell a unit for £25 (ex-VAT), and each unit costs £10 in materials, packaging and fees.

Contribution per unit = £25 − £10 = £15. Every sale puts £15 towards the £5,000. Break-even units = £5,000 ÷ £15 = 334 units (rounded up — 333 would leave you fractionally short, so the honest answer is the next whole unit). Break-even revenue = 334 × £25 = £8,350.

So you need 334 sales in the quarter before the business is in profit; sale 335 onward each adds a clean £15 to the bottom line. That is the entire calculation, and you can reproduce it by hand — which is the point.

Putting the number to work

A break-even figure is only worth having if it changes a decision. Three honest uses:

Pricing. Lifting the price raises the contribution per unit, which lowers the units you must sell twice over — fewer slices needed, and each is bigger. A £2 rise in the example takes contribution to £17 and break-even down to 295 units. Whether the market bears it is a separate question, but you can see exactly what the change buys you. The margin & markup calculator is the natural companion for setting the price itself.

Targets. "334 units this quarter" is roughly 26 a week — a far more useful sales target than a turnover figure plucked from optimism, and it tells you immediately whether the goal is plausible at your current capacity.

Scenario planning. Rents rise, a supplier increases prices, you take on a part-time hire. Each moves a cost, and re-running break-even shows the new floor before it surprises you. It also tells you how much slack you have if sales dip — and if cash is the pressing worry, the cash flow runway calculator answers the related question of how long the money lasts while you get back above the line.

Where break-even analysis stops being honest

It is a model, and models simplify. It assumes a single product at one price and one variable cost; if you sell a range, run it per product or use a weighted-average contribution rather than trusting one blended figure. It works in ex-VAT terms — feed it VAT-inclusive prices and the contribution is overstated. It assumes costs are linear: fixed costs flat, variable costs scaling evenly. Real businesses hit step costs — a second oven, a bigger unit, another salaried hire — and at that point your "fixed" costs jump and the break-even point resets higher. The analysis is excellent for a planning range; it is not a guarantee across every volume, and it is not financial advice — it is a starting point to sense-check against your own circumstances.

Next steps

Put your own fixed costs, price and unit cost into the break-even calculator — it shows the formula and a worked example next to the result, so you can verify the number rather than just take it.