Part of the CalcProMaster guides library · Updated September 2026
Business math fails most often in the same two spots: confusing margin with markup, and guessing break-even instead of computing it. These guides nail both.
Margin vs markup is a base confusion: margin is profit ÷ selling price, markup is profit ÷ cost. The same $10 profit on a $40-cost item selling at $50 is a 20% margin and a 25% markup — both correct, answering different questions. Pricing from a target margin needs the markup conversion: price = cost ÷ (1 − margin), so a 30% margin on $70 cost means $100, not $91.
Break-even converts that into planning: units = fixed costs ÷ (price − variable cost per unit). The denominator — contribution margin — is what each sale adds toward covering rent and salaries. The break-even guide runs a full café example, extends it to a target profit, and shows why a business below break-even loses money at roughly the contribution margin per unit, not at its full selling price.
One more distinction the guides keep returning to: profit is not cash. A profitable sale paid on 60-day terms still leaves payroll due on the 30th — which is why the break-even arithmetic a café needs is monthly, in cash terms, not annual. When you run the calculators, feed them the numbers from a real month (rent, average ticket, variable cost per order) rather than aspirational ones; the resulting break-even is then a line you can actually watch the business cross.
Fixed vs variable costs, contribution margin, a full café example, margin of safety, and the target-profit extension.
Break-Even Calculator Profit Margin Calculator Loan EMI Calculator