Margin and markup use different bases
Gross profit = selling price − cost. Margin = gross profit ÷ selling price × 100. Markup = gross profit ÷ cost × 100. For a target margin, price = cost ÷ (1 − target margin); for markup, price = cost × (1 + markup).
Example
A CAD 60 cost and CAD 100 selling price yield CAD 40 gross profit: a 40% margin and a 66.67% markup. A 40% markup on CAD 60 instead gives CAD 84, not CAD 100.
Target-margin prices round up to the next cent so the target is met. Margin targets must be below 100%; a positive cost is required for this mode. Undefined ratios at zero denominators are labelled. Gross profit does not subtract fixed overhead or income tax.
Source: BDC: gross profit margin (French source).