Most contractors price change orders the same way they price everything else — a quick markup on labor and materials and move on. The problem is that a markup on direct costs alone ignores overhead, which doesn't disappear just because the work wasn't in the original contract. On a change order with 25% overhead and a 15% profit target, a 30% markup on direct costs looks close enough — but it actually leaves money on the table and delivers a fraction of the margin you intended.

This calculator shows you the minimum price needed to hit your target margin on a change order, and compares it side by side against common markup approaches so you can see exactly where the gap is. Be sure to hit the ANALYZE button after selecting/changing inputs.