How many sales cover the costs? A break-even guide

A busy business can still be losing money. Break-even starts with a narrower question: at the price and costs you enter, how many sales would cover the included costs? The answer is a threshold to examine, not evidence that customers will buy that much.

What is left after each sale?

For one product, subtract variable cost per unit from selling price per unit. The difference is the contribution from each sale toward fixed costs. When that difference is positive, break-even units equal fixed costs divided by contribution per unit. The US Small Business Administration presents this formula in its business-planning guidance.

Fixed costs stay unchanged over the sales range being modelled; variable costs increase with each unit in this simplified calculation. Use one currency throughout. Fixed costs must describe a chosen period, while the price and variable-cost inputs describe one unit of the same product. The resulting sales threshold applies to that period.

A workshop with 1,200 in monthly fixed costs

Imagine a fictional workshop selling one kind of item for 30 currency units. Its variable cost is 18 per item and its fixed costs are 1,200 per month. Each sale contributes 30 − 18 = 12. Dividing 1,200 by 12 gives a threshold of 100 items sold per month. These figures are invented teaching assumptions, not a real business’s accounts.

• At 80 monthly sales: revenue is 80 × 30 = 2,400. Included costs are 1,200 + (80 × 18) = 2,640. The model shows a loss of 240.
• At 100 monthly sales: revenue is 3,000 and included costs are 3,000. The model breaks even.
• At 120 monthly sales: revenue is 3,600 and included costs are 3,360. The model shows a surplus of 240.

Now change variable cost to 20 and leave everything else unchanged. Contribution falls to 10, so the same fixed costs require 120 monthly sales. This comparison isolates one changed assumption; it does not forecast future costs or sales.

Why the calculator rounds up

For items that cannot be split, the first whole number of sales covering costs may produce a small surplus. If monthly fixed costs were 1,201 instead, 1,201 ÷ 12 would be about 100.0833. That means 101 whole items: revenue of 3,030, included costs of 3,019 and a surplus of 11. One hundred sales would still leave a loss of 1.

The calculator below reports this smallest whole-unit volume, revenue at that volume, included costs and surplus. Enter amounts with no more than two decimal places. It does not calculate a fractional-unit threshold for products sold in divisible quantities.

Check the cases the formula cannot solve

With positive fixed costs, a price equal to variable cost leaves nothing to cover those fixed costs. A lower price loses money on each additional sale. Neither case reaches break-even at a finite sales volume in this model. The calculator shows “Not reached” rather than dividing by zero or giving a negative target.

With zero fixed costs, zero sales already covers zero included costs. If price equals variable cost too, every volume breaks even; if price is lower, only zero sales avoids a loss. A zero-unit answer is an arithmetic result, not proof of a viable business.

Keep the model inside its limits

University of Missouri Extension explains that cost structures can change with scale: bulk buying can reduce unit costs, while more capacity can raise fixed costs. Its worked examples hold variable cost per unit and total fixed costs unchanged. Our calculator makes the same simplifying assumptions, with a constant selling price for one product.

Keep the cost list consistent and avoid counting the same expense as both fixed and variable. A business with several products, changing prices or a need for extra equipment requires a model that represents those conditions. Do not assume the current cost structure applies at every sales volume.

How we worked this out

We used exact invented amounts and checked revenue against fixed costs plus variable costs at each stated volume. The examples and calculator do not add tax, financing, inventory timing or capacity limits. They do not predict demand, payment timing or complete business profitability. Use the result to understand the included costs and assumptions, then examine the questions the arithmetic leaves open.