Ridge Cap Calculator

1. Enter the total ridge length in feet. For a gable roof this is typically the building length.
2. Enter the total hip length in feet. Enter 0 if the roof has no hips.
3. Select the coverage per bundle that matches your product. GAF Seal-A-Ridge covers 25 lin ft per bundle.
4. Select a waste factor: 10% is standard for most roofs.

Here is what each result line means:

For ridge and hip lengths, see the gable roof calculator or the hip roof calculator.

A ridge cap calculator estimates how many bundles of ridge cap shingles are needed to cover the ridge and hip lines of a roof. Ridge cap shingles are thick, pre-bent shingles designed to straddle the ridge and hip lines where two roof planes meet. They provide a finished look and a weather-tight seal at these vulnerable joints.

Factory-made ridge caps (such as GAF Seal-A-Ridge or IKO Hip and Ridge 12) are the standard for modern roofing. They are thicker and more contoured than hand-cut caps from three-tab shingles and provide better wind resistance.

The calculator adds the ridge and hip lengths, applies a waste factor and divides by the bundle coverage.

Step 1: Total Linear Footage

Measure all ridge lines (where two planes meet at the top) and all hip lines (where two planes meet at an outside corner). Add them together for the total.

Step 2: Bundles Needed

The waste factor accounts for cutting at ends and at hip-to-ridge intersections. The 10% standard factor works for most roofs.

A roof with 40 ft of ridge and 40 ft of hip, using GAF Seal-A-Ridge at 25 ft per bundle with 10% waste.

Step 1. Total = 40 + 40 = 80 ft.

Step 2. With 10% waste = 80 x 1.10 = 88 ft.

Step 3. Bundles = ceil(88 / 25) = ceil(3.52) = 4 bundles.

Total coverage = 4 x 25 = 100 ft. Excess = 100 – 88 = 12 ft.

Product Type

Factory-made ridge caps vary in coverage per bundle. GAF Seal-A-Ridge covers 25 lin ft, IKO Hip and Ridge 12 covers about 30 lin ft, and GAF Z Ridge covers about 34 lin ft. Always check the product label for exact coverage.

Hip Lines

A hip roof has four hip lines in addition to the ridge. Each hip line runs from the eave corner to the ridge end. Hip lines add significant footage. A 30 ft x 40 ft hip roof has about 40 ft of ridge and 76 ft of hips (4 x 19 ft). For hip dimensions, see the hip roof calculator.

Exposure

Ridge cap coverage depends on the exposure (the visible portion of each cap). GAF Seal-A-Ridge uses a 6-2/3-inch exposure for 25 ft per bundle. Installing at a different exposure changes the coverage. A tighter exposure uses more material per foot.

Waste Factor

Ridge caps waste material where hips meet the ridge and at the ends of each line. Use 10% for simple gable roofs and 15% for hip roofs with multiple intersections.

Three-tab Cut Caps

Some roofers cut ridge caps from three-tab shingles instead of using factory caps. A standard three-tab shingle yields 3 caps. At 5-inch exposure, one bundle covers about 32 ft. Factory caps are preferred for better wind resistance and appearance. For field shingle quantities, see the shingle calculator.

For the full roof area and shingle bundle count, see the roofing calculator.

New Roof Construction

Ridge caps are the last shingles installed. Order them with the field shingles so they are on site when the roofers reach the ridge.

Roof Replacement

Old ridge caps are removed during tear-off. Calculate replacements as part of the material order.

Material Budgeting

Ridge cap bundles typically cost more per piece than field shingles. Knowing the exact count prevents over-ordering. For underlayment, see the underlayment calculator.

Contractor Bid Verification

Check that a roofing bid separates ridge cap bundles from field shingle bundles. Some bids lump them together, which makes it hard to verify the quantities.

Hip Roof Estimation

Hip roofs use far more ridge cap than gable roofs because of the four hip lines. A hip roof may need twice the ridge cap of a gable roof with the same footprint. For hip roof dimensions, see the hip roof calculator.

1. Forgetting the Hip Lines

A hip roof has four hip lines that all need ridge cap. On a typical hip roof, the hip lines add more footage than the ridge itself. Omitting them leaves you short by half or more.

2. Using the Wrong Coverage per Bundle

Ridge cap coverage ranges from 20 to 34 lin ft per bundle depending on the product. Using 25 ft/bundle when the product covers 20 ft/bundle will underestimate by 20%. Always check the product label.

3. Confusing Ridge Cap Bundles with Field Shingle Bundles

Field shingles cover area (square feet). Ridge cap covers length (linear feet). You cannot substitute one calculation for the other.

4. Not Allowing Waste at Intersections

Where hip lines meet the ridge, the ridge cap pieces must be trimmed to fit. Each intersection wastes about 1 to 2 ft of material. The waste factor accounts for this. For drip edge at the eaves, see the drip edge calculator.

5. Installing at the Wrong Exposure

The coverage per bundle assumes a specific exposure (e.g., 6-2/3 inches for GAF Seal-A-Ridge). Installing at a tighter exposure uses more caps per foot and reduces the coverage per bundle.

This calculator uses manufacturer-stated coverage per bundle at recommended exposure.

Add the total ridge and hip linear footage, multiply by 1.10 for waste, and divide by the coverage per bundle for your product. Round up to whole bundles.

It depends on the product. GAF Seal-A-Ridge covers 25 lin ft, IKO Hip and Ridge 12 covers about 30 lin ft, and GAF Z Ridge covers about 34 lin ft. Always check the label.

Three-tab shingles can be cut into ridge caps (3 caps per shingle). However, factory-made ridge caps are thicker, more contoured and provide better wind resistance. They are the standard for most modern roofing jobs.

Yes. Hip lines are outside corners where two roof planes meet and they need ridge cap just like the ridge. A hip roof uses significantly more ridge cap than a gable roof.

Follow the manufacturer recommendation. GAF Seal-A-Ridge uses 6-2/3-inch exposure. IKO Hip and Ridge uses 5-5/8-inch exposure. Using a different exposure changes the coverage per bundle.

No. Ridge cap shingles cover the ridge line. Ridge vent is a ventilation strip installed under the ridge caps. You need both if the roof has ridge ventilation.

Each hip runs diagonally from the eave corner to the ridge end. For a rectangular hip roof, hip length equals the square root of the sum of half the building width squared plus the building rise squared.

Use 10% for a simple gable roof with only a ridge. Use 15% for a hip roof with multiple hip-to-ridge intersections that create cutting waste.

No. Starter strip is a separate product for the eave edge. This calculator covers only ridge and hip cap shingles.

No. The calculation runs entirely in your browser and nothing you enter is stored or sent anywhere.

• GAF, All About Hip and Ridge Cap Shingles (ridge cap types, factory vs cut caps, installation guidance).
• Lowes, GAF Seal-A-Ridge 25 lin ft per Bundle (GAF Seal-A-Ridge coverage: 25 lin ft per bundle, 45 pieces).
• IKO, Hip and Ridge 12 Technical Data Sheet (IKO coverage: 29.53 lin ft per bundle, 21 shingles yielding 63 pieces).
• GAF, Z Ridge Distinctive Ridge Cap Shingles Sell Sheet (GAF Z Ridge: 33.75 lin ft per bundle, 72 pieces).