Break-even analysis estimates the sales volume at which contribution equals fixed costs.
Break-even units = fixed costs ÷ contribution margin per unit
Break-even sales revenue = fixed costs ÷ contribution margin ratio
The result is an operating threshold under stated price, cost and sales-mix assumptions. It is not a forecast that demand will reach that level.
Build the inputs
Classify costs by how they behave over the relevant volume range. Calculate unit contribution as selling price minus variable unit cost. Divide fixed costs by unit contribution and round up.
Fixed costs
Fixed costs do not change with each unit inside the relevant planning range. Examples can include base rent, fixed software subscriptions, salaried administrative roles and minimum service retainers.
Variable costs
Variable costs change with sales volume. Ecommerce examples can include product cost, packaging, payment fees, pick-and-pack fees, shipping subsidies and expected returns cost.
Some costs are mixed or step-fixed. A warehouse contract may stay fixed until volume crosses a capacity threshold, then increase. The model should use the cost behavior expected inside the scenario rather than forcing every expense into a permanent label.
Worked single-product example
Assume an online product has:
- selling price of $80;
- variable unit cost of $44;
- monthly fixed costs of $12,000.
Unit contribution is:
$80 - $44 = $36
Break-even units are:
$12,000 ÷ $36 = 333.33 units
Partial units cannot be sold, so the operating threshold rounds up to 334 units.
The contribution margin ratio is:
$36 ÷ $80 = 45%
Break-even sales revenue is:
$12,000 ÷ 0.45 = $26,666.67
At 334 whole units, actual sales revenue is $80 × 334 = $26,720. The small difference comes from rounding units upward.
Use the Break-even Point Calculator to reproduce the unit result and the Contribution Margin Calculator to verify the price and variable-cost inputs.
Verify the result
At 334 units:
| Line | Calculation | Amount |
|---|---|---|
| Revenue | 334 × $80 | $26,720 |
| Variable costs | 334 × $44 | $14,696 |
| Contribution | 334 × $36 | $12,024 |
| Fixed costs | $12,000 | |
| Operating result | $12,024 - $12,000 | $24 |
At 333 units, contribution is $11,988, leaving a $12 shortfall. This verification confirms why the unit threshold must be rounded up.
Stress-test the result
Run lower-price, higher-cost and lower-volume scenarios. Add step-fixed costs when exceeding capacity requires another employee, warehouse or software tier.
| Scenario | Price | Variable cost | Unit contribution | Fixed costs | Break-even units |
|---|---|---|---|---|---|
| Base | $80 | $44 | $36 | $12,000 | 334 |
| 10% discount | $72 | $44 | $28 | $12,000 | 429 |
| Variable cost increase | $80 | $50 | $30 | $12,000 | 400 |
| New capacity tier | $80 | $44 | $36 | $15,000 | 417 |
| Price increase with same cost | $88 | $44 | $44 | $12,000 | 273 |
The table isolates one change at a time. In practice, price can also change conversion, sales mix, returns and acquisition cost. Treat the scenarios as arithmetic boundaries rather than demand predictions.
Add a target profit
Break-even produces zero operating profit under the model. To plan a target operating profit:
Target units = (fixed costs + target profit) ÷ unit contribution
With the base inputs and a $6,000 target profit:
($12,000 + $6,000) ÷ $36 = 500 units
This is a pre-tax operating target unless taxes and other items are modeled separately.
Multi-product break-even requires a sales mix
For a multi-product store, use a weighted average contribution based on expected sales mix. Recalculate when that mix changes materially.
Suppose product A contributes $30 per unit and represents 60% of expected units. Product B contributes $50 and represents 40%.
Weighted contribution = ($30 × 60%) + ($50 × 40%) = $38
With $15,200 fixed costs, the weighted break-even estimate is:
$15,200 ÷ $38 = 400 total units
At the assumed mix, this means 240 units of A and 160 units of B. If the actual mix shifts toward product A, total contribution falls and the business needs more units to break even. A weighted average is not stable when merchandising, advertising or availability changes the mix.
Decision checks before acting
- Confirm the period for fixed costs and expected sales.
- Separate variable, fixed, mixed and step-fixed behavior within the relevant range.
- Reconcile contribution with actual order or service economics.
- Test price, variable cost and capacity scenarios.
- Check whether the required volume is operationally possible.
- Check whether demand can plausibly support the required volume without assuming the answer.
- Recalculate when sales mix or cost contracts change.
Common mistakes
- Using gross margin dollars while omitting other variable costs.
- Mixing monthly fixed costs with annual sales volume.
- Forgetting to round break-even units upward.
- Treating all payroll or software as permanently fixed.
- Assuming price changes do not affect volume or mix.
- Applying a single-product formula to a changing product portfolio.
- Calling break-even revenue a demand forecast.
Break-even analysis is useful because it exposes the relationship between cost structure and required volume. Its quality depends on the classification of costs and the realism of the operating range.
Sources
- OpenStax: contribution margin and contribution margin ratio; OpenStax; accessed Jul 13, 2026
- OpenStax: break-even point in units and dollars; OpenStax; accessed Jul 13, 2026
This guide is educational and does not provide financial, accounting, tax or legal advice.