The idea: contribution margin
Each sale contributes price minus variable cost toward your fixed costs — that difference is the contribution margin. Break-even is simply fixed costs divided by contribution margin per unit. Selling $40 products that cost $15 to deliver, each sale contributes $25; with $5,000 of monthly fixed costs, you need 200 sales a month before profit exists.
Getting the cost split right
- Fixed costs don't move with volume: rent, salaries, software subscriptions, insurance, loan payments.
- Variable costs scale with each unit: materials, packaging, shipping, payment-processing fees, sales commissions, per-order labor.
- Gray areas (marketing, utilities) go wherever they honestly behave in your business. When unsure, treating a cost as fixed gives the more conservative break-even.
What to do with the number
Compare break-even volume with realistic market demand — 200 units a month means nothing until you ask whether 7 sales a day is plausible for your channel. Then use the calculator as a sandbox: a $5 price rise cuts the example's break-even from 200 to 167 units; trimming $5 of unit cost does the same. Price changes usually move break-even more than heroic cost-cutting does.
The margin of safety
Once selling above break-even, the gap between actual sales and break-even sales — the margin of safety — tells you how much demand can fall before losses start. Selling 260 units against a 200-unit break-even means a 23% cushion. Thin cushions argue for building cash reserves before scaling spending.