Drip Edge Calculator: Pieces for Eaves & Rakes
Add up your eave and rake edges and enter the piece length to get the number of drip-edge pieces to buy. A 5% allowance for the overlap at each joint is built into the count.
Calculator
180 LF of eaves and rakes (plus 5% for laps) is 19 pieces of 10 ft drip edge.
Drip edge is the metal flashing installed along the edges of the roof — the eaves at the bottom and the rakes up the sloped sides. It directs runoff into the gutter and away from the fascia, and it gives the shingles a clean, supported edge. Because it runs along the perimeter edges, it is measured in linear feet and bought in sticks — most commonly 10-foot pieces.
The one adjustment the raw length needs is for overlap. Each stick laps the next by an inch or two so water cannot get behind the joint, and every corner needs a cut, so the material you buy is a little more than the bare edge length. This tool adds a standard 5% for laps and then rounds up to whole pieces. If those same eaves also carry gutters, size them with the gutter length calculator.
Formula
Pieces are edge length plus 5% laps, over the piece length, rounded up:
pieces = ⌈ (eave_lf + rake_lf) × 1.05 ÷ piece_length ⌉
- eave_lf + rake_lf — total of the bottom edges and the sloped side edges.
- 1.05 — a 5% allowance for laps at every joint and corner.
- piece_length — length of one stick (usually 10 ft).
Worked example
Edge a roof with 180 LF of eaves and rakes using 10 ft pieces:
- With laps: 180 × 1.05 = 189 LF of drip edge.
- Pieces: 189 ÷ 10 = 18.9, rounded up to 19 pieces.
Nineteen 10-foot sticks cover the edges with the laps accounted for. Buy an extra stick or two if your roof has many corners, since each corner miter wastes a little material.
Edge & flashing notes
Practical drip-edge points:
- Eave vs. rake order. Drip edge goes under the underlayment at the eaves but over it at the rakes. That does not change the quantity, but it does change the install sequence.
- Profiles differ. Common profiles are the L-style (Type C) and the T-style (Type D / extended). They cover the same linear feet but look and shed water a bit differently — pick one before ordering.
- Corners cost material. Every corner needs a miter or overlap; a cut-up roof with lots of corners wastes more than a simple rectangle, so lean toward rounding up.
- Match the metal to the job. Aluminum and galvanized steel are the usual choices; coastal and high-exposure roofs often specify a heavier gauge or a specific finish.
Reference table
Pieces by edge length (with 5% for laps) at 10 ft per piece:
| Eave + rake | With laps | Pieces |
|---|---|---|
| 80 LF | 84 LF | 9 |
| 120 LF | 126 LF | 13 |
| 160 LF | 168 LF | 17 |
| 180 LF | 189 LF | 19 |
| 220 LF | 231 LF | 24 |
| 280 LF | 294 LF | 30 |
Frequently asked questions
How many pieces of drip edge do I need?
Add up your eave and rake length, add 5% for laps, and divide by the piece length. For 180 LF with 10 ft pieces: 180 × 1.05 = 189, then 189 ÷ 10 = 18.9, rounded up to 19 pieces.
What is the difference between eaves and rakes?
Eaves are the horizontal bottom edges of the roof, where the gutters hang; rakes are the sloped edges that run up the gable ends. Drip edge goes on both, so add their lengths together for the total you enter here.
Why add 5% for drip edge?
Each 10 ft stick overlaps the next by an inch or two so water cannot slip behind the joint, and every corner needs a cut. That overlap and waste is roughly 5% of the bare edge length, which this tool adds before rounding up to whole pieces.
What size drip edge should I buy?
Drip edge comes in profiles like L-style (Type C) and T-style (Type D). They cover the same linear feet but the T-style extends further out over the fascia and sheds water better. The quantity is the same either way — choose the profile first, then use this count.
Does drip edge go on before or after underlayment?
Both, in different places: it is installed under the underlayment along the eaves and over the underlayment along the rakes. The sequence matters for water-shedding but does not change how many pieces you buy.