It's a strikingly common gap: founders who can describe their product, their customer and their marketing plan in detail, but who've never actually calculated the one number that tells them whether the whole thing can work — the break-even point, the volume of sales needed just to cover costs, before a single pound of profit appears.
Why this matters before launch, not after
Calculated early, break-even is a planning tool — it tells you whether the volume of sales required is remotely realistic given your actual market, and it forces an honest look at pricing and costs before either is locked in by momentum.
Calculated after launch, once premises are leased and stock is bought, it's just an uncomfortable fact you now have to live with rather than a decision you can still change. By then the fixed costs are already committed, and the only lever left is working harder to hit a number that a five-minute calculation would have flagged as unrealistic months earlier.
If you don't know your break-even number, you don't actually know whether your business plan works. You know that it sounds plausible, which is a different thing entirely.
How to actually calculate it
Add up your fixed costs for a typical month — rent, salaries, subscriptions, anything you pay regardless of how much you sell. Work out your gross margin per sale — price minus the direct cost of delivering it.
Divide fixed costs by that margin, and you have the number of sales needed each month just to break even. It's a rough calculation, not a precise science, but a rough calculation genuinely done beats a plan that's never run the numbers at all. Most spreadsheet templates for this take under half an hour to fill in properly.
What to do once you have the number
Ask honestly: is that volume realistic given your actual market size and marketing plan, on a realistic timeline, not a hopeful one? Compare it against what similar local businesses actually seem to be doing, not what you'd need to be true for the plan to work.
If the honest answer is no, that's exactly the moment to revisit pricing, costs or the whole model — while it's still a spreadsheet, not a business already trading at a loss with a lease that can't be undone.
