Roofing Calculator
Squares, shingle bundles and underlayment rolls for your roof, from the footprint and the pitch.
Roof & Roofing Materials
Enter the footprint and the pitch. Every rate below is editable.
The roof as seen from above, overhangs included. Outline it on a satellite map in LandLens to get this number.
Use the main roof pitch. For roof sections with different pitches, calculate each section on its own.
Roof area
Materials to order
Most shingles come 3 bundles to a square and synthetic underlayment rolls cover about 1,000 sq ft. Check the wrapper of the products you buy. Use about 10% waste for a simple gable roof and 15% or more with hips and valleys.
How it's calculated
- Pitch factor = √(1 + (rise ÷ 12)²) for an x/12 pitch, or 1 ÷ cos(angle) for a pitch in degrees. A 6/12 roof has a factor of 1.118.
- Roof surface = footprint × pitch factor. A 2,000 sq ft footprint at 6/12 is 2,236 sq ft of roof.
- 1 roofing square = 100 sq ft of roof surface, so 2,236 sq ft is 22.4 squares.
- Order = roof surface × (1 + waste %). With 10% waste: 24.6 squares × 3 bundles = 74 bundles, and 3 rolls of 1,000 sq ft underlayment.
Rates are typical values you can change, not a manufacturer's spec. Ridge caps, starter strips and flashing are not included.
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About the Roofing Calculator
This roofing calculator turns the footprint of a house and the roof pitch into a materials list: the sloped roof surface, roofing squares with waste, shingle bundles (or tiles in metric) and underlayment rolls. Each rate is an input, so you can match the products you actually buy.
Measure the footprint on a satellite map
You don't need to climb on the roof to get the footprint. In LandLens, outline the roof edge on the satellite map and the app gives you the area seen from above. Enter that area here with the pitch, and the calculator adds the slope.
Why use this calculator
- Pitch built in - x/12 or degrees, converted with the exact pitch factor
- Squares and bundles - roof surface, squares with waste and whole bundles to order
- Your rates, not ours - waste, bundles per square and roll coverage are editable
- US or metric - squares and bundles, or m² and tiles
Frequently Asked Questions
How many squares is my roof?
Multiply the footprint by the pitch factor and divide by 100. A 2,000 sq ft footprint with a 6/12 pitch has 2,236 sq ft of roof, which is 22.4 squares before waste.
How many bundles of shingles do I need?
Most shingles come 3 bundles to a square. Add waste to the roof surface first: 22.4 squares plus 10% is 24.6 squares, so you need 74 bundles. Check the wrapper, because some heavy shingles come 4 or 5 bundles to a square.
How much waste should I add for a roof?
About 10% for a simple gable roof. Hip roofs, valleys, dormers and many cut lines need 15% or more.
Does the calculator include ridge caps and starter strips?
No. It covers the field of the roof and the underlayment. Ridge caps, starter strips, drip edge and flashing are ordered by length, so measure the ridges and eaves separately.
Can I measure the roof without climbing on it?
Yes. Outline the roof edge on a satellite map to get the footprint, then enter the pitch. You can read the pitch from the plans, or measure the rise over 12 inches of run from the attic or a ladder at the gable end.
Get the footprint from the satellite map
Outline any roof or building on a satellite map and get its area in seconds with LandLens.
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