Roofing material calculator
Turn your measurements into a shopping list.
Roof preview
Calculation breakdown — every section
Building lengths in ft; areas in sq ft. Overhang is horizontal and added on both ends of each dimension. Calculations use unrounded values; displayed figures may not add exactly.
| Section / shape | Wall dimensions | Overhang per side | Roof footprint | Pitch / multiplier | Surface area / share |
|---|---|---|---|---|---|
| Section Agable | 40.00 × 30.00 ft | 1.00 ft | 42.00 × 32.00 ft1,344.00 sq ft | 6.00:12× 1.11803 | 1,502.64 sq ft100.00% of total |
- Surface area before waste
- 1,502.64 sq ft
- Waste allowance (10%)
- 150.26 sq ft
- Order area including waste
- 1,652.90 sq ft · 16.53 roofing squares
Independent rectangular sections only. Overlaps, shared edges and valleys are not automatically deducted or constructed. Hip sections require equal pitch on every face. Confirm joined-roof measurements separately.
Package quantities round up after waste. Current assumptions: shingles 33.33 sq ft/bundle; underlayment 400.00 sq ft effective coverage/roll; cap 25.00 ft/bundle. These product settings use feet even when geometry is displayed in meters. Match the packaging and manufacturer’s overlap instructions before ordering.
Planning estimate only. Excludes labor, tax, removal, delivery, starter strips, flashing, ventilation, fasteners and deck repairs.
Calculation breakdown — every section
Building lengths in ft; areas in sq ft. Overhang is horizontal and added on both ends of each dimension. Calculations use unrounded values; displayed figures may not add exactly.
| Section / shape | Wall dimensions | Overhang per side | Roof footprint | Pitch / multiplier | Surface area / share |
|---|---|---|---|---|---|
| Section Agable | 40.00 × 30.00 ft | 1.00 ft | 42.00 × 32.00 ft1,344.00 sq ft | 6.00:12× 1.11803 | 1,502.64 sq ft100.00% of total |
- Surface area before waste
- 1,502.64 sq ft
- Waste allowance (10%)
- 150.26 sq ft
- Order area including waste
- 1,652.90 sq ft · 16.53 roofing squares
Independent rectangular sections only. Overlaps, shared edges and valleys are not automatically deducted or constructed. Hip sections require equal pitch on every face. Confirm joined-roof measurements separately.
Package quantities round up after waste. Current assumptions: shingles 33.33 sq ft/bundle; underlayment 400.00 sq ft effective coverage/roll; cap 25.00 ft/bundle. These product settings use feet even when geometry is displayed in meters. Match the packaging and manufacturer’s overlap instructions before ordering.
Planning estimate only. Excludes labor, tax, removal, delivery, starter strips, flashing, ventilation, fasteners and deck repairs.
Example arithmetic checked October 28, 2026 against independent geometry reference cases. Measurement method. This is a software calculation check, not a professional roof survey.
From roof area to roofing materials
Start with the actual roof surface area and add an explicit waste allowance. Divide that order area by each product’s effective coverage and round up to full bundles or rolls. Keep coverage and waste separate to avoid counting the same allowance twice.
How many bundles are in a roofing square?
Many asphalt shingles use three bundles per 100 sq ft, but this is not universal. Enter the actual coverage per bundle from the packaging.
How much waste should I allow?
10% is the starting assumption in this calculator, not a recommendation for every roof. More cuts, hips, valleys, material patterns and installation constraints can increase waste. Your installer should confirm the allowance.
Does the estimate include every roofing item?
No. It estimates field shingles, underlayment, ridge and hip cap bundles, and drip edge. Starter strips, fasteners, flashing, ventilation, decking, ice barriers and labor must be specified separately.
Does it price the whole job?
No. The optional cost is a shingles-only subtotal using the bundle price you enter. It does not include taxes, labor, delivery, removal or other materials.
How many shingle bundles do you need?
First calculate the roof’s sloped surface area. Multiply by 1 + waste percentage ÷ 100, divide by the manufacturer’s coverage per bundle, then round up. One roofing square is 100 square feet, regardless of pitch.
Bundles = round up(roof area × (1 + waste ÷ 100) ÷ coverage per bundle)
| Roof area | Order area | Order squares | Bundles |
|---|---|---|---|
| 1,000 sq ft | 1,100 sq ft | 11.0 | 33 |
| 1,500 sq ft | 1,650 sq ft | 16.5 | 50 |
| 2,000 sq ft | 2,200 sq ft | 22.0 | 66 |
| 2,500 sq ft | 2,750 sq ft | 27.5 | 83 |
These are examples, not product specifications. If your shingles cover a different area per bundle, use that value. Do not multiply by pitch again if your starting figure already measures the sloped roof surface.
Underlayment, caps and drip edge
Underlayment rolls use effective coverage after overlaps. Ridge and hip caps use linear coverage per bundle. Drip edge uses roof-edge length and the effective length per piece. Shared edges, intersections and installation overlaps may need manual adjustments.
What to check before ordering
Ask your installer or supplier to confirm waste, starter strips, fasteners, flashing, ventilation, decking and ice barriers. The calculator’s optional price is for field shingle bundles only. It is not a replacement-roof quotation.
Method: geometric roof planning estimates. Updated September 27, 2026. Verify measurements and product specifications before ordering.