How to measure a roof for shingles
Measure each roof face, find its pitch, then turn the plan measurements into the real sloped area, squares and bundles. A worked example and a free calculator are at the end.
What to bring
- A tape measure (a long one for the eaves) or a laser measure
- A level and a short tape, or a pitch gauge, for the pitch
- Something to note each face: paper, or a MesuPro sheet on your phone
Safety first: on a roof, use fall protection, never work alone, and stay off a wet, icy or windy roof. When in doubt, measure from the ground, from a ladder at the eave or from the attic: the method below works all three ways.
Step by step
Split the roof into faces
Each sloped plane is a face: a gable roof has two, a hip roof four or more. Measure and note each face on its own, dormers and small faces too.
Measure the width along the eave
For each face, measure its bottom edge, along the eave. On a rectangular face it is the same at the top; on a triangle or a trapezoid, use the average of the bottom and top edges.
Measure the horizontal run
The run is the face's depth seen from above, from the eave to the ridge, measured flat. From the ground, measure the building's depth and keep the part under this face (half of it for a simple gable roof), plus the overhang. In the MesuPro template you can also enter the slope length if you measure it: it uses the larger of the two. The free calculator uses the run.
Find the pitch
The pitch is the rise for 12 of run. Rest one end of a level on the roof or on a rafter and hold it level, mark 12 in from that end, then measure the vertical distance between the level and the roof at that mark: that is the pitch (6 in means 6/12). From the attic, do it on a rafter.
Turn it into squares and bundles
The pitch gives a factor that turns the flat run into the real sloped length. Add the waste, divide by 100 sq ft for squares, and count 3 bundles per square, rounded up.
The calculation
Pitch factor = square root of (1 + (pitch / 12)²). Real area = width x horizontal run x pitch factor. 10% waste by default, as in the template. Squares = area with waste / 100 sq ft. Bundles = 3 per square, rounded up.
Worked example
A face 42 ft wide along the eave, with a 14 ft horizontal run and a 6/12 pitch, 10% waste: pitch factor 1.118, real area 657.4 sq ft, 723.1 sq ft with waste, 7.23 squares, so 22 bundles.
Common mistakes
- Using the flat (plan) area: a 6/12 roof is about 12% larger than its footprint, a 12/12 roof about 41%.
- Leaving the overhang out of the run or the width.
- Mixing feet and inches: 14 ft 6 in is 14.5 ft, not 14.6.
- Leaving out small faces: dormers and porch roofs add up.
Roofing: from the slope to the bundles
The whole job in MesuPro
Roofing: measurement and materials
Real sloped area from the pitch, squares, shingles, underlayment, ridge cap and drip edge.
Feet and inches by default
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