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Business & Tax
Before launch, know the number: how many units cover your costs. Break-even math, contribution margin, and a worked example for founders.
By FreeCalculators Editorial · Published 2026-05-18 · Updated 2026-08-20 · 4 min read · 936 words
Break-even analysis answers the question every startup founder asks before launch: how many units do I have to sell to stop losing money? The answer is rarely as big as you fear or as small as you hope, and knowing it before you spend on inventory changes which risks you take. Break-even is not a sales prediction — it is a floor. Below it you lose cash every month; above it you start funding the future.
Break-even math only works if you can sort your costs honestly into two buckets, and the sorting is harder than it looks. Get a cost in the wrong bucket and your break-even number will be fiction.
The core number is contribution margin per unit: price minus variable cost. This is how much each sale contributes to covering your fixed costs. Break-even units equal fixed costs divided by contribution margin per unit, and break-even revenue is that unit count times the price.
Break-even for a $45 subscription box
Price per box = $45, variable cost per box = $17 Contribution margin = 45 - 17 = $28 per box Fixed costs per month = $8,400 Break-even units = 8,400 / 28 = 300 boxes per month Break-even revenue = 300 x 45 = $13,500 per month At 250 boxes you lose 50 x 28 = $1,400 each month
For a startup, break-even has two phases. Operating break-even covers monthly fixed costs — that is the 300 boxes above. The full picture adds one-time launch costs: equipment, the first inventory run, logo and site work, and deposits. Amortize those across the first year to find the true monthly target.
If launch costs are $36,000, that is $3,000 per month over twelve months. Add it to fixed costs and your honest first-year break-even is (8,400 + 3,000) / 28, or about 407 boxes a month. That is the number to plan against — the one that pays for the printer and the logo as well as the rent.
Break-even is not static. Every price change, supplier renegotiation, or rent increase moves it, so re-run the math whenever a cost changes by more than a few percent. Three levers matter most:
A break-even number is only useful if your cost estimates are real. Quote variable costs from actual supplier prices, not hopes, and add a 10 to 15 percent buffer on fixed costs in your first year. Founders who under-estimate costs usually discover the mistake around month four, when the bank balance delivers the message.
Comprehensive Guide
Read our business and tax guide for margins, payroll, and tax planning.
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How this guide was created
This guide was written and reviewed by FreeCalculators Editorial, drawing on published formulas, official government sources, and real calculator outputs from our 4 calculators in this category. Every claim is sourced; every formula is auditable. Read our review policy.