HourlyMath

Break-Even Analysis, Explained Like You're Opening a Sandwich Shop

Updated July 2026 · 5 minute read

Break-even analysis answers the only question every business plan must survive: how much do I have to sell before this stops losing money? The math is genuinely simple — one subtraction, one division — and the discipline of doing it exposes fantasy plans faster than any other single number. Let's open a sandwich shop and find out.

Two kinds of costs

Every cost in a business is one of two species. Fixed costs arrive whether you sell anything or not: rent, insurance, salaries, software, the loan payment — the meter that runs while you sleep. Variable costs attach to each unit sold: ingredients, packaging, card-processing fees, per-unit labor. The sandwich shop: $6,000/month of rent, wages, insurance, and utilities (fixed); $4 of bread, fillings, and packaging per sandwich (variable). Some costs are honestly a bit of both — utilities creep with volume — but forcing each into a bucket is most of the work, and most of the insight.

Contribution margin: the hero of the story

Sell the sandwich for $12, spend $4 making it, and each sale contributes $8 — not profit yet, but ammunition against the fixed costs. This per-unit number is the engine of everything: it's what each additional sale is actually worth to you. (Its percentage cousin is the gross margin from margin vs markup — same idea, different clothes.)

The formula, and the shop's number

$6,000 ÷ $8 = 750 sandwiches a month — about 29 per working day. Sandwich #749 still leaves the month at a loss; sandwich #751 is the first that earns a dollar (well, eight). That concreteness is the point: "29 a day" can be stared at, compared to foot traffic, and believed or disbelieved. A plan that needs 300 sandwiches a day from a side street has been falsified for the price of a division. To find the break-even in revenue instead of units, divide fixed costs by the contribution margin ratio (8 ÷ 12 = 66.7%): $6,000 ÷ 0.667 = $9,000/month of sales.

Making the number move

Only three levers exist, and running them through the sandwich shop shows their surprisingly unequal power. Raise the price to $13: contribution jumps to $9, break-even drops to 667 — an 11% improvement from an 8% price change, because every dollar of price lands straight in the margin. Cut variable cost by $1 (cheaper supplier): identical effect, 667. Cut fixed costs by $600 (smaller space): 675. Price is usually the strongest lever and the most feared one — which is why underpricing (often via the margin/markup confusion) is so expensive: it raises the hill you must climb every single month before earning anything.

What the number is for

Beyond go/no-go on a new venture, break-even referees everyday decisions. Hiring ($3,000/month of new fixed cost = 375 more sandwiches — does traffic support that?). Equipment ("pays for itself" claims become checkable: divide the cost by the contribution it adds or saves). A second location (its own fixed costs, its own break-even, its own verdict). Freelancers, same skeleton: your fixed costs are your living expenses and business overhead, your "price" is your rate, and break-even is the billable hours that cover the month — the logic inside how to set your freelance rate.

Run yours

The break-even calculator takes fixed costs, price, and variable cost, and shows units, revenue, and what each lever does — live, as you type. The honest caveats: real businesses sell more than one product (use a weighted average contribution, or your bestseller as a proxy), and break-even is a floor, not a goal — the real target is break-even plus the profit you're in business for. Add that profit to the fixed costs and the same formula tells you the sales that deliver it.