Almost every business calculation — pricing, break-even, profit planning — starts with sorting costs into two buckets: fixed and variable. Getting this distinction right is the foundation of business finance.
Fixed Costs
Fixed costs stay the same no matter how much you produce or sell. Rent, insurance, salaries, a loan payment, and software subscriptions are all fixed — you owe the same amount whether you sell one unit or a thousand. They're predictable, but they're also due even in a slow month, which makes them a source of risk.
Variable Costs
Variable costs rise and fall with output. Every unit you make has a cost — materials, packaging, and per-unit labor. Sell more and variable costs go up; sell nothing and they're near zero. A pizza truck's dough, cheese, and boxes are variable; a clothing brand's fabric and shipping are variable.
Putting Them Together
Total costs = fixed costs + variable costs. Some costs are mixed (partly fixed, partly variable) — a phone plan with a base fee plus usage, for example — but most costs fall clearly into one bucket. Sorting them is the first step before any pricing or break-even work.
Why the Difference Matters
The split explains how profit changes as sales grow. Once fixed costs are covered, each new sale only has to beat its variable cost, so profit can rise quickly — that's why the contribution margin (price minus variable cost) is so important. It's also why a business with high fixed costs needs strong sales just to break even.
Key Takeaways
- Fixed costs don't change with output (rent, insurance, salaries, loan payments).
- Variable costs rise with each unit produced (materials, packaging, per-unit labor).
- Total costs = fixed + variable; some costs are mixed.
- The split drives pricing, contribution margin, and break-even analysis.
Keep Studying
Related: Break-Even Analysis, Income Statement.
These guides are educational explanations written for the AP Business with Personal Finance course.