The Margin and markup calculator is built for finding the selling price needed for a target gross margin on a known cost. It gives a transparent numerical result from the values on the form, so you can follow the arithmetic rather than treating the answer as a black box.
It is most useful for testing a price before fees, taxes and discounts are applied. Enter values from the same measurement, record or scenario. A polished answer cannot repair an input copied with the wrong unit, date or accounting meaning.
A 100% margin makes the denominator zero, so the page accepts values below 100%. Actual gross margin depends on which costs are classified as cost of goods sold.
