Roof Drip Edge Calculator

About this calculator

Drip edge is the L- or T-shaped metal flashing installed along a roof's eaves and rakes to direct water away from the fascia and into the gutter instead of behind it — required by most modern building codes at both edges. It's sold in fixed-length pieces (commonly 10 feet), installed with a small overlap (typically 2 inches) at each joint, so the number of pieces needed is more than a simple perimeter-length division.

This calculator takes your total eave and rake lengths, the piece length, and a waste percentage (to cover cutting losses at corners, valleys, and hips), and returns both the linear feet and the number of pieces to buy. Roofing contractors and DIY re-roofers use it when ordering material for a roofing job, since drip edge is a small line item that's easy to under-order if you only measure the roof's raw perimeter.