Markup is not margin
Markup divides gross profit by cost; margin divides gross profit by selling price. The companion view shows both so they are not accidentally substituted.
Enter cost and selling price to calculate markup.
Start with the broad calculator that matches the decision, then move to a specialist only when the loan structure, cash flow, tax treatment, debt strategy or savings goal genuinely changes.
Markup divides gross profit by cost; margin divides gross profit by selling price. The companion view shows both so they are not accidentally substituted.