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Break-even analysis: check the contribution first

Published by Navon Ventures S.A.S · October 20, 2026

A simple break-even model estimates the units needed to cover fixed costs. It separates fixed costs for a chosen period from variable cost per unit. This distinction is useful only when the price, costs and period refer to the same scenario. Break-even is not a cash-flow forecast or a guarantee that those units can be sold.

Find contribution per unit

Subtract variable cost per unit from selling price per unit. At a $50 selling price and $30 variable cost, contribution is $20. That $20 is available toward the fixed costs in this model. It is not automatically take-home profit, because the fixed costs have not yet been covered and omitted expenses are still outside the calculation.

Divide fixed costs and round up

With $2,500 in fixed costs for the same period, divide 2,500 by 20 to get 125 units. If fixed costs instead total $2,510, the quotient is 125.5. When only whole units can be sold, round up to 126: 125 units leave $10 uncovered, while 126 provide $2,520 of contribution. The break-even calculator performs this whole-unit step.

Recognize when the model has no finite answer

If variable cost equals the selling price, contribution is zero. Each additional sale contributes nothing toward positive fixed costs. If variable cost exceeds the price, each additional sale increases the shortfall under these assumptions. Dividing by zero or a negative contribution does not produce a useful positive unit target.

Test the assumptions, not just the number

Try separate scenarios for a lower selling price or a higher variable cost. Keep the fixed-cost period consistent; monthly fixed costs should not be compared directly with annual sales assumptions. The basic model assumes a constant unit price and cost and does not handle a changing product mix, capacity constraints or step changes in overhead. Payment timing also matters: a business can reach a modeled break-even point and still face cash constraints. Use the cash runway calculator for a separate, steady-burn illustration, and the margin calculator to explore an entered revenue-and-cost scenario.