Drip Edge Calculator
Reviewed by the My Roof Pitch editorial team · Updated · Free, no sign-up, works offline after first load
Drip edge comes in standard 10 foot pieces installed with about a 2 inch overlap at each joint. For 150 feet of combined eave and rake length, you need roughly 16 pieces after accounting for overlap and 10% waste, plus about 240 nails spaced every 12 inches.
Your measurements
Enter the values you know — results update live.
Combined horizontal eave length needing drip edge.
Combined sloped rake (gable edge) length needing drip edge.
Standard stock length is 10 ft.
Standard overlap is 2 inches.
Analysis
Live results from your measurements.
Add extra pieces for outside corners and any custom flashing details not captured by straight runs.
Show the working
- Raw length:
100 + 60= 160 ft - With waste:
160 × 1.1= 176 ft - Effective coverage per piece:
10 − (2 ÷ 12)= 9.83 ft - Pieces needed:
ceil(176 ÷ 9.83)= 18 - Nails needed:
ceil((176 × 12) ÷ 12) + (18 × 2)= 212 nails
What this calculator does
Drip edge is a metal flashing strip installed along roof eaves and rakes that directs water away from the fascia and into the gutter, rather than letting it wick back under the shingles or run down the fascia board. It comes in standard 10-foot stock lengths that get overlapped roughly 2 inches at each joint and fastened every 12 inches with roofing nails. The IRC requires drip edge at eaves and rakes on most residential roofs (R905.2.8.5), installed under the underlayment at eaves and over the underlayment at rakes. Calculating pieces correctly avoids ordering short and having a mismatched finish piece at the end of a run.
How to use it
- Measure the total eave length and total rake length separately, then add them together.
- Add a waste allowance, typically 10%, for corner cuts and mistakes.
- Subtract the overlap distance from the stock piece length to get the effective coverage per piece.
- Divide the total length to cover by the effective coverage per piece and round up.
- Multiply total length by 12 and divide by the nail spacing to estimate nails, adding a couple extra per piece for end fastening.
The formula
Effective coverage per piece
effective length = stock piece length − overlap
Each piece only adds its length minus what overlaps the previous piece.
Pieces needed
pieces = ceil(total length with waste / effective length per piece)
Rounds up to whole pieces since drip edge cannot be seamlessly joined mid-piece.
Nails needed
nails = ceil((total length × 12) / nail spacing) + 2 per piece
Adds extra fasteners at each piece's overlap joint beyond the regular spacing.
Worked example
A roof with 100 ft of eaves and 60 ft of rakes, 10 ft stock pieces, 2 in overlap, 10% waste, nails every 12 in.
- Raw length: 100 + 60 = 160 ft
- With waste: 160 × 1.10 = 176 ft
- Effective coverage: 10 − (2 ÷ 12) = 9.83 ft
- Pieces: ceil(176 ÷ 9.83) = 18
- Nails: ceil((176 × 12) ÷ 12) + 18 × 2 = 176 + 36 = 212
Order 18 pieces of 10 ft drip edge and about 212 roofing nails.
Reference chart
| Total length | Pieces needed | Nails needed |
|---|---|---|
| 100 ft | 12 | 135 |
| 150 ft | 17 | 199 |
| 200 ft | 23 | 267 |
| 250 ft | 28 | 331 |
| 300 ft | 34 | 398 |
Common drip edge profiles
| Profile | Use | Typical length |
|---|---|---|
| Type C / L-style | Flat roofs, low-slope eaves | 10 ft |
| Type D / T-style | Standard shingle roofs, deeper flange | 10 ft |
| Type F / gutter apron | Eaves feeding directly into a gutter | 10 ft |
Common mistakes
- Installing drip edge over the underlayment at eaves instead of under it — eaves are under, rakes are over, per most code adoptions.
- Skipping overlap entirely and butting pieces end to end, which leaves a gap for water to sneak through.
- Forgetting outside corner pieces or custom miters at hips and valleys that meet the eave.
- Under-ordering because the eave and rake lengths were measured from a rough estimate instead of the actual roof plan.
- Using too few nails, letting wind lift the flashing at the overlap joints.
Assumptions and limits
- Pieces are standard 10 ft stock; custom lengths may change the piece count.
- A uniform overlap and nail spacing are applied across the whole run.
- Outside corner pieces and custom flashing details are not included in the piece count.
Frequently asked questions
How much drip edge do I need for my roof?
Add your total eave length and total rake length, apply about 10% waste, then divide by the effective coverage of each 10 ft piece (about 9.83 ft after a 2 in overlap) and round up.
Does drip edge go over or under the underlayment?
At eaves, drip edge is installed under the underlayment (or under ice and water shield). At rakes, it is installed over the underlayment. This is required by IRC R905.2.8.5 in most jurisdictions.
What size overlap does drip edge need?
About 2 inches of overlap at each joint is standard practice, enough to keep water from finding a path between pieces.
How are drip edge nails spaced?
Roofing nails are typically spaced every 12 inches along the inner flange, with additional nails at the overlap joints.
What length does drip edge come in?
10 foot lengths are the standard stock size at most suppliers, though some carry 8 ft or 12 ft options.
Do I need drip edge at both eaves and rakes?
Yes, most codes require drip edge along all eaves and rakes, not just the eaves, to protect the roof edge and fascia from wind-driven rain.
What metal is drip edge made from?
Aluminum and galvanized steel are the most common, with aluminum being easier to cut and more corrosion-resistant in coastal areas.
Can drip edge be reused when re-roofing?
It is possible if it is in good condition and properly fastened, but most roofers replace it during a tear-off since it is inexpensive relative to the labor of carefully removing and reinstalling it.
Last updated 2026-10-08. Results are estimates for planning and are not a substitute for a licensed engineer or local code review.