How the Break-Even Calculator Works
The calculator works from three inputs: total fixed costs, the selling price per unit and the variable cost per unit. It first finds the contribution margin per unit = price − variable cost (what each sale contributes towards fixed costs once its own variable cost is paid) and the contribution-margin ratio = contribution margin ÷ price (the share of every sales dollar left to cover fixed costs). From these it computes the break-even point in units = fixed costs ÷ contribution margin, and the break-even revenue = fixed costs ÷ contribution-margin ratio, which is the same as break-even units × price. For example, $50,000 of fixed costs with a $50 price and $30 variable cost gives a $20 contribution margin (40% ratio), a 2,500-unit break-even and $125,000 of break-even revenue. Optionally it computes the units for a target profit = (fixed costs + target profit) ÷ contribution margin, and the margin of safety from expected sales. Every result comes from a pure function in a small, unit-tested engine, shown live with a pure-SVG chart of the revenue and total-cost lines.
- Contribution margin / unit = selling price − variable cost / unit
- Contribution-margin ratio = contribution margin ÷ price
- Break-even units = fixed costs ÷ contribution margin per unit
- Break-even revenue = fixed costs ÷ contribution-margin ratio
- Break-even units are rounded up — you cannot sell a fraction of a unit
