Roofing Calculator: Roof Area, Pitch and Squares

Calculate your quantities

Enter your measurements below. Change the example allowance, product information and price to match your project.

Enter measurements and select Calculate.

Prices use your chosen currency. A zero price leaves cost at zero. Material estimates exclude labor, tax, delivery and accessories. Enter decimal feet, not feet-and-inches notation. Decimal point or comma accepted; omit thousands separators.

How to use this roofing calculator

Enter the full horizontal roof footprint including overhangs. Assumes one uniform pitch, such as a simple gable roof. Do not double a footprint that already covers both slopes. Complex roofs need separate non-overlapping sections. Default bundle coverage is illustrative; use the product label.

Measure the relevant area or volume using the units shown beside each input.
Replace example product values with the supplier's yield, coverage, density or pack quantity where applicable.
Set the extra allowance explicitly. Enter zero when you want the geometric quantity without an allowance.
Select Calculate, then compare the unrounded purchasing basis with whole bags, boxes or packs where displayed.

Formula

Slope factor = √(1 + (rise / 12)²). Roof area = horizontal projected area × slope factor. Material area = roof area × (1 + extra / 100). Roofing squares = material ft² / 100. Bundles = material ft² / bundle coverage, rounded up.

Worked example

A 10 × 10 ft roof footprint with 6:12 pitch has 111.803 ft² of sloped area. With 10% extra, material area is 122.984 ft² = 1.230 roofing squares. At 33.333 ft² per bundle, round up to 4 bundles.

Six calculated examples

Only the first length changes in this table. All other inputs use the calculator's reset values shown above. These are mathematical scenarios, not measured supplier quotes.

roofing quantity examples
First length	Calculated quantities
5 ft	Roof area (ft²): 55.902; Material area (ft²): 61.492; Roofing squares: 0.615; Bundles: 2
8 ft	Roof area (ft²): 89.443; Material area (ft²): 98.387; Roofing squares: 0.984; Bundles: 3
10 ft	Roof area (ft²): 111.803; Material area (ft²): 122.984; Roofing squares: 1.23; Bundles: 4
12 ft	Roof area (ft²): 134.164; Material area (ft²): 147.58; Roofing squares: 1.476; Bundles: 5
15 ft	Roof area (ft²): 167.705; Material area (ft²): 184.476; Roofing squares: 1.845; Bundles: 6
20 ft	Roof area (ft²): 223.607; Material area (ft²): 245.967; Roofing squares: 2.46; Bundles: 8

Frequently asked questions

Is this structural design?

No. It estimates covering area and quantities from supplied dimensions.

Can I use measured slope length?

These inputs expect horizontal projection. Do not enter slope length as horizontal length.

Are ridge caps and underlayment included?

No. Accessories, flashing and separate product coverage need their own quantities.

Units and calculation limits

One foot is 0.3048 meters; one cubic yard is 27 cubic feet. Calculations retain precision until display; whole-package quantities are rounded up. Outputs estimate quantities from your measurements and assumptions. Confirm product coverage and units before ordering.