Roofing Calculator
Work out the roof area and how many squares and bundles of shingles to order - just enter the footprint of the house and the roof pitch.
How to use this roofing calculator
Measure the length of the house along the ridge and the width from eave to eave in feet. That footprint is the flat area your roof covers; the pitch factor below adjusts it to the true sloped surface.
Pick the roof pitch: 3/12 (a gentle slope) adds about 3% to the area, 6/12 about 12%, 9/12 about 25%, and 12/12 (a steep 45-degree roof) a full 41% more.
Roofing is sold in squares of 100 sq ft and bundles - three bundles cover one square. Add 5% waste on a simple roof, or 10% when there are valleys, hips and edges to cut.
Roofing calculator FAQ
How many bundles of shingles are in a square?
Three bundles typically cover one square (100 sq ft) of 3-tab or architectural shingles. Heavier luxury shingles come four bundles to a square - check the bundle label for its exact coverage.
How do I measure the pitch of my roof?
Hold a level at 12 inches along the roof surface, measure straight down to the roof at that point - that vertical rise is your pitch. A 6-inch rise is a 6/12 pitch. On steep or high roofs, estimate from a photo of the gable end instead.
How much does a square of shingles cost?
Three-tab shingles cost roughly $90-$110 per square and architectural shingles $120-$200 per square in the US (2025-2026), installed labor adds about the same again. Most roofers quote per square.