Break-even analysis for small businesses: units, revenue, and price

Every business has a number that separates “we lost money this month” from “we made money this month”, and it is usually not the revenue number in the accounting software. It is the break-even point: the sales level where revenue exactly covers costs and profit is zero. Above it, every sale contributes profit; below it, every sale contributes loss. Here is how to find it in five minutes with two numbers you already have.

The two-step formula

The first step is the contribution margin: price minus variable cost per unit. This is the money each sale contributes to covering your fixed costs — the costs that exist whether you sell anything or not.

• Fixed costs stay the same regardless of sales: rent, salaries, insurance, software subscriptions, equipment.
• Variable costs change with every unit: materials, packaging, per-unit shipping, payment processing fees.

Then the break-even point falls out in two versions:

• In units: fixed costs ÷ contribution margin. This is how many units you must sell.
• In revenue: fixed costs ÷ contribution margin ratio, where the ratio is contribution ÷ price. This is the dollar amount of sales.

Worked example: a physical product

A small maker sells a product at $12 with $4 of variable costs — materials, packaging, and processing. The contribution margin is $8 per unit, a ratio of 8 ÷ 12 = 66.7%. Monthly fixed costs — workshop rent, insurance, subscriptions, a part-time helper — come to $10,000.

• Break-even in units: 10,000 ÷ 8 = 1,250 units per month.
• Break-even in revenue: 10,000 ÷ 0.667 = $15,000 per month.

The table shows how the ledger looks at each level:

Units sold	Revenue	Variable cost	Contribution	Fixed cost	Profit
800	$9,600	$3,200	$6,400	$10,000	−$3,600
1,000	$12,000	$4,000	$8,000	$10,000	−$2,000
1,250	$15,000	$5,000	$10,000	$10,000	$0
1,500	$18,000	$6,000	$12,000	$10,000	+$2,000
2,000	$24,000	$8,000	$16,000	$10,000	+$6,000

Every unit above 1,250 adds $8 of profit; every unit below it subtracts $8. That is the whole leverage of a business: the contribution margin per unit, repeated across volume.

Worked example: a service

The same math works for services, where the “units” are hours or clients. A freelance consultant charges $120/hour, pays $20/hour in variable costs (tools, subcontracting, processing), and has $4,000/month of fixed costs (software, insurance, accounting).

• Contribution per hour: $100; ratio: 83.3%.
• Break-even in hours: 4,000 ÷ 100 = 40 hours per month.
• Break-even in revenue: 4,000 ÷ 0.833 = $4,800 per month.

The service version has a subtlety worth naming: hours are not unlimited. If the consultant can realistically sell 100 hours a month, the break-even point is 40% of capacity — which means the price, not the effort, is what deserves scrutiny if profit is thin.

What the number is really telling you

Break-even is a threshold, not a target — and it is the fastest honest check on three business decisions:

• Pricing: raise the price from $12 to $14 and the contribution margin rises to $10, dropping break-even from 1,250 to 1,000 units. The question becomes volume: can you sell at least 1,000 at the higher price? The price-and-volume trade is the same calculation every profit margin discussion eventually reaches.
• Cost control: cutting variable cost by $1 (a cheaper supplier, a better shipping rate) raises contribution to $9 and drops break-even to 1,112 units — no price change needed.
• Fixed-cost decisions: every new fixed cost — a hire, a subscription, a bigger space — moves the break-even line up. The hire is only justified if the added capacity sells more than the extra break-even volume.

The assumptions to check

Break-even math is deterministic; the inputs are where reality enters. Three assumptions deserve a skeptical look before you rely on the number:

1. Cost classification. Is that “part-time helper” fixed or variable? If they only work when orders exist, they are variable. The same cost placed in the wrong bucket shifts break-even by thousands.
2. Linear costs. The formula assumes variable cost per unit stays constant. A volume discount on materials lowers it; overtime wages raise it. At the extremes of the volume curve, the line bends.
3. Price stability. Selling everything at list price is the assumption; discounts and channel fees reduce realized price per unit, which is a different (higher) break-even than the sticker-price version.

The break-even calculator runs both versions of the formula — units and revenue — from your price, variable cost, and fixed costs, and shows the monthly profit at the sales level you actually expect, so the threshold is visible against a realistic volume rather than in the abstract. The cash runway calculator answers the follow-up question: how long the current cash balance lasts while you climb toward break-even.

The one rule

Sort every cost into fixed or variable first — the formula is only as honest as that classification. Then the break-even point is one division: fixed costs divided by contribution margin, and every unit above it is the profit margin repeated. Know that number cold; it is the line between growing and merely working.