About the profit margin calculator
Margin and markup describe the same gap between cost and price, but they divide by different numbers, and mixing them up is one of the most expensive small-business arithmetic errors there is. Margin is profit as a share of the selling price. Markup is profit as a share of the cost. A 50% markup is only a 33.3% margin.
This calculator runs in two directions. In forward mode you enter cost and revenue, and it returns gross profit, margin percentage and markup percentage together, so you can see both framings of the same trade at once. In reverse mode you enter your cost and the margin you want, and it returns the price you need to charge to achieve it.
Reverse mode is the one most people actually need. If you know a product costs you forty and you want a 35% margin, dividing forty by 0.65 gives 61.54 — not forty multiplied by 1.35, which lands at fifty-four and a margin of only 26%. That gap compounds across every unit you sell.
The tool also shows the breakeven point in units when you supply fixed costs, which is useful when you are deciding whether a price change is worth it. Lowering a price by ten percent on a thirty percent margin means selling roughly fifty percent more units just to stand still.
Figures are gross — they compare direct cost against revenue. Overheads that are not tied to a single unit belong in the fixed-cost field rather than in the unit cost.