Roof slope length and area

Roof Length Calculator

Convert roof run, pitch, and overhang into sloped roof length, then use the roof width and plane count to estimate order area and roof squares. It is built for roof length, pitch length, and material takeoff searches that need a quick field number.

Units

Horizontal roof run (ft)Eave overhang (ft)Roof pitch (in / 12)Roof width along eave (ft)Roof planes Waste / laps (%)Roofing cost ($/sq)

Sloped roof length

Order area

Roof squares / measured area

Rough cost

Roof length is geometry, not roof design

This calculator estimates slope length and area for simple roof planes. Dormers, hips, valleys, penetrations, starter courses, laps, ventilation, fastening, and local code can change the final order.

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Roof Pitch Calculator

Convert rise, run, pitch, angle, and multiplier before estimating roof length.

Metal Roof Length Calculator

Use panel-specific length and panel counts for metal roofing.

Roof Shingle Calculator

Turn roof area and squares into shingle bundles.

View all

Roof length formula

Slope run = horizontal run + overhang

Rise = slope run × pitch ÷ 12

Roof length = sqrt(slope run² + rise²)

Order area = roof length × roof width × roof planes × (1 + waste %)

Sample takeoff

A 12 ft run with 1 ft overhang at 6/12 pitch has a 14.53 ft sloped roof length. Across a 40 ft roof on two planes with 10% waste, order about 1,279 ft², or 12.8 roof squares.A 3.6 m run with 0.3 m overhang at 6/12 pitch has a 4.36 m sloped roof length. Across a 12 m roof on two planes with 10% waste, order about 115.1 m².

Roof Length Calculator FAQ

How do I calculate roof length from pitch?+

Add the overhang to the horizontal run, calculate rise from pitch, then use the Pythagorean theorem to find the sloped roof length.Add the overhang to the horizontal run, calculate rise from pitch, then use the Pythagorean theorem to find the sloped roof length.

Is roof length the same as rafter length?+

They are related, but rafter length can include ridge deductions, birdsmouth layout, and framing details. This page is a roof-plane length and material takeoff check.They are related, but rafter length can include ridge deductions, birdsmouth layout, and framing details. This page is a roof-plane length and material takeoff check.

How many roof squares do I need?+

In imperial units, divide the order area by 100. Add waste for cuts, hips, valleys, starter courses, and product laps.In imperial units, divide the order area by 100. Add waste for cuts, hips, valleys, starter courses, and product laps.