$
Rent, salaries, software — costs that do not move with sales.
$
What the customer pays for one.
$
What each extra sale costs you to make and deliver.
Contribution / unit$37.0075.5% margin
Break-even units217to cover fixed costs
Break-even revenue$10,633per month
This is the simple, single-product model. It assumes one price and one variable cost, ignores tax, and treats fixed costs as flat. Real businesses have a mix — but the logic (price must beat variable cost, and the gap has to cover fixed costs) is the same. Nothing you type leaves the page.