Roofing Calculator
Your estimate
- Squares (100 ft²)
- 16.53
- Underlayment rolls
- 5
- Ridge & hip cap length
- 42 ft12.8 m
- Estimated cost
- $7,438
Gable, hip or shed roofs — area, squares, bundles of shingles (or roof tiles) and an estimated cost.
Updated 2026-10-20 · Based on: roof-pitch geometry and 3 shingle bundles per square.
How to use the Roofing Calculator
- Enter the house length and width (the footprint) and the overhang.
- Enter the pitch (x/12 in feet mode, degrees in metric).
- Pick the roof type and keep 10 % waste (15 % for complex roofs).
- Read squares and bundles, or tiles for metric roofs.
Formula
Roof area = (length + 2 × overhang) × (width + 2 × overhang) × pitch multiplier × (1 + waste).
One square = 100 ft². Three-tab and architectural shingles come 3 bundles per square.
Worked example
With the values preset in the calculator above:
- House length
- 40 ft
- House width
- 30 ft
- Overhang
- 1 ft
- Roof pitch
- 6 in per 12 in
- Roof type
- Gable
- Extra for waste
- 10 %
- Roof tiles per m²
- 12 per m²
- Roof area (with waste)
- 1,652.9 ft² (183.66 yd²)
- Squares (100 ft²)
- 16.53
- Underlayment rolls
- 5
- Ridge & hip cap length
- 42 ft (12.8 m)
- Estimated cost
- $7,438
How many bundles of shingles in a square?
Three bundles cover one square (100 ft²) for most three-tab and architectural shingles; heavy designer shingles may need 4 or 5. A 40 × 30 ft house with 1 ft overhangs and a 6/12 pitch has about 16.53 squares with 10 % waste — 50 bundles.
Related guides
Frequently asked questions
How do I calculate roofing squares?
Work out the roof area in ft² (footprint × pitch multiplier) and divide by 100.
Does a hip roof need more shingles?
The area is the same as a gable of the same pitch, but hips mean more cutting and more ridge cap — use 15 % waste.
How much does a new roof cost?
Asphalt shingle roofs typically run $400–$700 per square installed in 2026, more for metal, tile or steep roofs.
More calculators
Estimates only — check quantities with your supplier and local building code before you order.