Drip Edge & Ridge Cap Calculator
Calculate drip edge linear feet and pieces for eaves and rakes, plus hip & ridge cap bundles, from your roof edge measurements. IRC R905.2.8.5.
Horizontal bottom edges.
Sloped side edges.
Horizontal peaks.
Sloped hips (also get cap).
Varies by product — often ~20–25 lin ft. Check your bundle.
Edge & ridge takeoff
132 lin ft (eave + rake).
44 lin ft (ridge + hip).
- Eave drip edge
- 80 ft
- Rake drip edge
- 40 ft
- Ridge cap
- 40 ft
- Waste applied
- 10%
Drip edge goes on eaves AND rakes. Code (IRC R905.2.8.5) requires drip edge at both on shingle roofs.
At eaves, drip edge goes UNDER the underlayment; at rakes, OVER. (Some regions/codes vary — verify.)
Pre-formed hip & ridge shingles are standard — coverage per bundle varies by product (often ~20–25 linear ft). Check your bundle.
Hips get ridge cap too, not just the main ridge — count both.
If you’re installing a ridge vent, you still need ridge cap over the vent.
How this calculator works
Drip edge and ridge cap are the finishing trim that completes a shingle roof, and both are notorious for being under-ordered. This calculator takes both off the roof's linear measurements at once, because that is how they are estimated in the field — from eave, rake, ridge, and hip lengths rather than from area.
Drip edge: eaves and rakes
Drip edge runs along every roof edge. IRC R905.2.8.5 requires it at the eaves and along the rakes on shingle roofs, so the total is eave length plus rake length, with waste, converted to stock pieces. The installation order is worth remembering: at the eaves the drip edge tucks under the underlayment so water sheds onto it, while at the rakes it goes over the underlayment.
Ridge cap: ridges and hips
Hip and ridge cap covers the peaks — both the horizontal main ridge and every sloped hip. Forgetting the hips is the classic shortfall. The modern standard is pre-formed hip & ridge sold by the bundle, with coverage that varies by product (commonly 20–25 linear feet), so the calculator divides your ridge-plus-hip length by the bundle coverage you enter. A legacy cut-from-3-tab mode is available, but never cut caps from thick architectural shingles.
Working with a ridge vent
If you are installing a ridge vent, you still need ridge cap over the top of it — the vent does not replace the cap. Toggle the ridge-vent option to also see the ridge-vent linear feet. To size the attic airflow itself (net free area, intake versus exhaust balance), use the attic ventilation calculator. As always, verify edge and ventilation details against your local code.
Frequently asked questions
- How much drip edge do I need?
- Add your total eave length and total rake length, add about 10% for overlaps and corner waste, then divide by your stock piece length (usually 10 ft) and round up. For example, 80 ft of eave plus 40 ft of rake is 120 ft, about 132 ft with waste, which is 14 ten-foot pieces. The calculator does this and splits the eave and rake totals for you.
- Does drip edge go on rakes too, or just eaves?
- Both. IRC R905.2.8.5 requires drip edge at eaves and along rake edges on shingle roofs. The installation order differs, though: at the eaves the drip edge goes under the underlayment, while at the rakes it goes over the underlayment. Some regions and codes vary, so verify locally, but plan to order enough for every edge.
- How many bundles of hip & ridge shingles do I need?
- Add the ridge length and the hip length, add about 10% waste, and divide by the coverage per bundle. Pre-formed hip & ridge typically covers around 20–25 linear feet per bundle, but it varies by product, so check your specific bundle. For 40 ft of ridge plus 20 ft of hip at 22 ft per bundle, that is 3 bundles.
- Do hips need ridge cap?
- Yes. Hips get the same hip & ridge cap treatment as the main ridge — they are a finished, capped edge. It is a common mistake to count only the horizontal ridge and come up short. Enter your total hip length and the calculator folds it into the ridge cap quantity.
- Can I cut ridge caps from regular shingles?
- Historically caps were cut from 3-tab shingles at about a 5-inch exposure, roughly three caps per shingle, and the calculator offers that mode. But do not cut caps from architectural (dimensional) shingles — they are too thick and stiff to fold cleanly. The modern standard is matching pre-formed hip & ridge, which is what you should default to.
- Do I need ridge cap if I have a ridge vent?
- Yes. A ridge vent sits in the slot at the peak, but it still needs ridge cap shingles installed over it to shed water and finish the look. Toggle the ridge-vent option to also see the ridge-vent linear feet (equal to your ridge length); it does not reduce the cap you need. If you are also sizing attic airflow, see the attic ventilation calculator.