Roofing
Roof Calculator Calculator USA 2026
Estimate roofing squares, bundles of shingles and rolls of underlayment for gable, hip and shed roofs.
Unit system
Enter your measurements
Results
Roof area
1344 sq ft
Squares
13.4
Shingle bundles
41
Underlayment rolls (400 sq ft)
4
Calculation steps
- 1.Footprint = 40 × 30 = 1200 sq ft
- 2.Roof area = 1200 × 1.12 = 1344 sq ft
- 3.Squares = 1344 ÷ 100 = 13.44
- 4.Bundles = ⌈13.44 × 3⌉ = 41
Includes a standard waste allowance. Verify with your supplier before ordering.
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Disclaimer: Estimates based on 2026 RSMeans USA data. Actual quantities vary by site conditions, waste and installer practices. Verify with your supplier or contractor before ordering.
How it works
- 1Measure the building footprint (length × width).
- 2Apply the pitch multiplier (1.06 for 4/12, 1.12 for 6/12, 1.20 for 8/12).
- 3Divide by 100 to get roofing squares; 3 bundles ≈ 1 square.
Formula
Roof Area = Footprint × Pitch Multiplier → Squares = Area ÷ 100
Worked example
40×30 ft footprint at 6/12 pitch = 1200 × 1.12 = 1344 sq ft = 13.4 squares ≈ 41 bundles.
Frequently asked questions
How many bundles per square?
Three bundles of architectural shingles = one square (100 sq ft).