Roofing Square Foot Calculator

Q: What is a roofing square?

A roofing square equals 100 square feet of roof area. A 2,000 sq ft roof requires 20 roofing squares. Shingles are sold in bundles, with 3 bundles typically equaling 1 roofing square.

Q: How do I account for roof pitch in my calculation?

Multiply the flat footprint area by the pitch factor: 3/12 pitch = 1.031, 4/12 = 1.054, 5/12 = 1.083, 6/12 = 1.118, 8/12 = 1.202, 10/12 = 1.302, 12/12 = 1.414.

What is roofing square footage?

Roofing square footage is the total sloped roof area. Multiply roof footprint × slope factor. A 4/12 pitch uses 1.06. A 6/12 pitch uses 1.12. A 12/12 pitch uses 1.42. For attic and ceiling insulation, see the insulation calculator.

Getting started

How to Calculate Roofing Square Footage

To calculate roofing square footage, measure the building footprint length × width in feet. Multiply by the slope factor for actual roof area. Roofing is sold per "square" (100 sq ft). Add 10-15% for ridge caps, valleys, and waste.

1. Measure footprint

Measure length × width of the building from the ground in feet.

2. Apply slope multiplier

4/12 pitch: 1.06. 6/12 pitch: 1.12. 8/12 pitch: 1.20. 12/12 pitch: 1.42.

3. Calculate squares

One roofing square = 100 sq ft. Divide total area by 100 to get squares.

Quick reference

Reference

1 acre = 43,560 square feet

1 square yard = 9 square feet

1 square meter = 10.764 square feet

1 square inch = 0.00064516 square feet

Material pricing

Calculate Cost of Materials

Asphalt shingles cost $90-200 per square installed. Metal roofing costs $200-600 per square. Multiply squares needed by price per square for total cost.

There are 2 steps to calculate material cost:

Enter price per square (100 sq ft) or per bundle (1/3 square = ~33 sq ft).
The Square Foot Calculator divides roof area by square or bundle size and multiplies by price for total cost.

Order 10-15% extra for ridge, valley, and wind loss. Add felt, drip edge, and labor separately.

FAQ

Frequently Asked Questions

How do I calculate roof square footage?

Measure the roof footprint (length x width from the ground), then multiply by the pitch factor. A 40x30 ft footprint (1,200 sq ft) with a 6/12 pitch: 1,200 x 1.118 = 1,342 sq ft of actual roof area.

What is a roofing square?

A roofing square equals 100 square feet of roof area. A 2,000 sq ft roof requires 20 roofing squares. Shingles are sold in bundles, with 3 bundles typically equaling 1 roofing square.

How many shingles do I need per square foot?

Standard 3-tab shingles require about 3 bundles per roofing square (100 sq ft). For a 1,500 sq ft roof, you need 15 squares or 45 bundles of shingles, plus 10-15% for waste.

How do I account for roof pitch in my calculation?

Multiply the flat footprint area by the pitch factor: 3/12 pitch = 1.031, 4/12 = 1.054, 5/12 = 1.083, 6/12 = 1.118, 8/12 = 1.202, 10/12 = 1.302, 12/12 = 1.414.

How much does roofing cost per square foot?

Asphalt shingles cost $3.50-5.50/sq ft installed, metal roofing costs $7-14/sq ft, and tile roofing costs $10-20/sq ft. A 2,000 sq ft roof with asphalt shingles typically costs $7,000-11,000.

How many squares is a typical house roof?

A typical single-story home has 15-25 roofing squares (1,500-2,500 sq ft of roof area). Two-story homes have smaller roof footprints, typically 10-20 squares.

REFERENCES

Roofing Square Foot
Calculator — Roof Area Tool

Explore Our Square Footage Calculators