Hip & Ridge Length Calculator

Calculate main ridge length, hip line length, and valley linear feet from building dimensions and roof pitch for accurate ridge cap and hip shingle ordering

Enter building dimensions and roof type to calculate ridge and hip line lengths

Quick presets

ft
ft

Total Linear Feet

268 LF

Ridge: 20 LF • hip roof

PRO

Professional Calculator

Extended parameters for precise calculations

sq ft

Estimated Materials

60 bundles

Roof Area

1,792 sq ft

Squares

17.9

Detailed Breakdown

Roof Area1,792 sq ft
With Waste1,971 sq ft
Roofing Squares17.9
Bundles60
How to Use This Calculator
The Hip & Ridge Length Calculator converts your building dimensions and roof pitch into precise linear footage for every ridge, hip, and valley line on your roof. This is critical for ordering the right amount of ridge cap shingles, ridge vent, hip shingles, and valley flashing — materials that are easy to underestimate and cause project delays when you run short.

Dimensions tab: Enter your building length, width, and roof pitch, then select the roof configuration. The calculator instantly computes the main ridge length (building length minus building width for a standard hip) and the total hip line length using the 3D diagonal formula that accounts for both the plan-view diagonal and the vertical rise from the pitch. For a gable roof, the ridge equals the full building length and there are no hip lines. For a cross-hip, the calculator adds the intersecting ridges and additional hip lines at the cross junction.

Ridge & Hip Lines tab: This tab provides a more detailed breakdown. You can add valleys (from additions, wings, or dormers) and dormer ridge lines. The calculator computes each valley's actual length based on the horizontal run and pitch angle. Dormer ridges are typically 4-8 feet each and add two short valley lines per dormer. The output is a complete inventory of every linear element on your roof — main ridge LF, total hip LF, total valley LF, and dormer ridge LF — all adjusted for the actual 3D length including pitch factor.

Materials tab: Enter the linear footage totals from the previous tabs and select your ridge cap product and ridge vent type. The calculator converts linear feet to material quantities: ridge cap bundles (accounting for different coverage rates between factory and field-cut products), ridge vent sections with overlap allowance, and valley flashing pieces. The waste factor applies on top of the base quantities to ensure you have enough material for cuts and fitting at intersections.

The Formula
The hip and ridge length calculator uses these formulas:

Main Ridge Length (standard hip) Ridge LF = Building Length - Building Width Example: 50 ft long, 30 ft wide → Ridge = 50 - 30 = 20 LF Note: If Length ≤ Width, ridge = 0 (pyramid hip)

Hip Line Length (each) Run = Building Width / 2 Rise = Run × (Pitch Rise / 12) Hip Length = √(Run² + Run² + Rise²) = Run × √(2 + (Pitch/12)²) Example: 30 ft wide, 5/12 pitch → Run = 15, Rise = 6.25, Hip = √(225 + 225 + 39.06) = 22.1 ft each Total for 4 hips = 4 × 22.1 = 88.4 LF

Valley Length Valley LF = √(2 × Run² + Rise²) Example: 12 ft run, 5/12 pitch → Rise = 5, Valley = √(288 + 25) = 17.7 LF

Ridge Cap Bundles Bundles = (Total Ridge LF + Total Hip LF) × (1 + Waste%) / Coverage per Bundle Example: (20 + 88.4) × 1.10 / 25 = 4.77 → order 5 bundles

Ridge Vent Sections Sections = Ridge LF × 1.05 (overlap) / Section Length Example: 20 LF × 1.05 / 4 ft = 5.25 → order 6 sections (4-ft)
Example Calculation
Example: 50×30 Standard Hip Roof at 5/12 Pitch

Tom has a simple rectangular hip roof on his 50-foot by 30-foot ranch home with a 5/12 pitch. He is ordering materials for a full re-roof and needs to know the ridge cap, ridge vent, and hip shingle quantities.

Step 1: Main Ridge Length
• Ridge = Building Length - Building Width = 50 - 30 = 20 LF of main ridge

Step 2: Hip Line Length (each of 4 hips)
• Run = 30 / 2 = 15 ft
• Rise = 15 × (5/12) = 6.25 ft
• Hip length = √(15² + 15² + 6.25²) = √(225 + 225 + 39.06) = √489.06 = 22.1 ft per hip
• Total hip lines: 4 × 22.1 = 88.4 LF

Step 3: Total Linear Feet Needing Ridge Cap
• Ridge: 20 LF
• Hips: 88.4 LF
• Total: 108.4 LF

Step 4: Ridge Cap Bundles (IKO Hip & Ridge @ 25 LF/bundle)
• 108.4 × 1.10 (10% waste) = 119.2 LF
• 119.2 / 25 = 4.77 → Order 5 bundles ($35-$50 each = $175-$250)

Step 5: Ridge Vent (shingle-over, 4-ft sections)
• Vent runs along main ridge only: 20 LF
• 20 × 1.05 (overlap) / 4 = 5.25 → Order 6 sections ($8-$15 each = $48-$90)

Step 6: Summary
• Ridge cap shingles: 5 bundles
• Ridge vent: 6 four-foot sections
• No valleys or dormers on this simple roof
• Total ridge/hip materials cost: $225-$340

Frequently Asked Questions

How do I calculate the main ridge length on a hip roof?
On a standard hip roof, the main ridge length equals the building length minus the building width. This is because each end of the ridge transitions into two hip lines that descend to the building corners, and the horizontal run of each hip end consumes half the building width from each side. For example, a 50-foot-long by 30-foot-wide building has a main ridge of 50 - 30 = 20 feet. If the building is square (length equals width), the ridge length is zero — the four hip lines meet at a single peak point, which is called a pyramid hip. For gable roofs, the ridge runs the full length of the building, so the same 50-foot building has a 50-foot ridge.
How do I calculate hip line length from dimensions and pitch?
Each hip line on a standard hip roof runs diagonally from a building corner up to the end of the main ridge. The hip line length is calculated as the square root of (run squared + run squared + rise squared), where the run is half the building width and the rise equals the run multiplied by the pitch ratio. For a 30-foot-wide building at 5/12 pitch: run = 15 feet, rise = 15 × (5/12) = 6.25 feet, hip length = sqrt(15² + 15² + 6.25²) = sqrt(225 + 225 + 39.06) = sqrt(489.06) = 22.1 feet per hip line. A standard hip roof has four hip lines, so the total hip line length is 4 × 22.1 = 88.4 feet. Alternatively, you can compute it as: hip length = run × sqrt(2 + (pitch)²), where pitch = rise/run per foot.
How many bundles of ridge cap do I need for a hip roof?
To calculate ridge cap bundles, add the total ridge length plus the total hip line length, then divide by the coverage per bundle. Factory ridge cap shingles like IKO Hip & Ridge cover approximately 25 linear feet per bundle. Premium products like GAF Timbertex cover about 20 linear feet per bundle. For a roof with 20 feet of ridge and 88 feet of hip lines: total = 108 LF. With factory caps at 25 LF/bundle: 108 / 25 = 4.32 bundles, rounded up to 5 bundles. Add 10% waste for a total order of 5 to 6 bundles. Hip lines typically use slightly more material per foot than flat ridges because of the sharper angle, so some contractors add 15% waste for hip lines specifically.
How do I measure valley length on a roof?
Valley length is measured along the line where two roof planes intersect at an inward angle. The valley runs at approximately 45 degrees in plan view (when viewed from above) and is also angled by the roof pitch. The formula for valley length is: valley length = sqrt(2 × horizontal_run² + rise²), where the horizontal run is the distance from the valley start to the ridge line measured along one of the roof planes, and the rise is that run multiplied by the pitch. For a valley with a 12-foot horizontal run at 5/12 pitch: rise = 12 × 5/12 = 5 feet, valley length = sqrt(2 × 144 + 25) = sqrt(313) = 17.7 feet. Each valley needs either metal W-flashing (sold in 10-foot pieces with 6-inch overlap) or woven/cut shingle treatment using field shingles.
Should I install ridge vent along the entire ridge on a hip roof?
On a hip roof, ridge vent should run the full length of the main ridge to maximize exhaust ventilation, but it typically does not extend along the hip lines. The main ridge is the highest point of the roof and provides the strongest stack-effect airflow. Hip lines are lower and angled, making them less effective for ventilation and harder to install vent products on. For very short ridges (under 10 feet on near-square buildings), some roofers supplement with hip ridge vents or power vents to ensure adequate exhaust. The total NFA from the ridge vent must be balanced with intake ventilation at the soffits — ideally 50% intake and 50% exhaust. A 20-foot ridge with standard shingle-over vent provides approximately 12.5 square inches of NFA per linear foot, totaling about 250 square inches or 1.74 square feet of NFA.

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Related Guides & Resources

How to Measure a Roof Understanding Roof Pitch Roof Pitch Chart