Roofing Calculator

Calculate roof area, roofing squares, shingle bundles, and total project cost. Works for gable, hip, shed, and flat roofs at any pitch.

Select roof type 4 roof shapes
ft
Longest side of the building footprint
ft
Width of the building footprint
ft
Typical: 1–2 ft
$
Avg $25–$60/bundle; $75–$180/sq
Frequently asked questions
What is a roofing square? ›
A roofing square is 100 square feet of roof area. It's the standard unit contractors and suppliers use to price and order roofing materials. A typical 2,000 sq ft house with a 6/12 pitch roof has about 22–25 squares of actual roof surface — the pitch adds area beyond the flat footprint.
How many bundles of shingles do I need per square? ›
Most 3-tab and architectural shingles come 3 bundles per square (covering 100 sq ft). Some premium or thick-cut shingles require 4 bundles per square. Always check your specific shingle product — the bundle label will state how many square feet it covers. Each bundle weighs about 75–80 lbs for 3-tab and 85–90 lbs for architectural shingles.
How does roof pitch affect the amount of shingles needed? ›
A steeper pitch means more actual roof surface than the flat footprint. A flat roof (1/12 pitch) has a multiplier of about 1.003 — almost no difference. A 6/12 pitch has a multiplier of about 1.118 — you need 12% more shingles than the floor area. A 12/12 pitch (45°) has a multiplier of 1.414 — 41% more shingles than the footprint. This calculator applies the correct multiplier automatically.
What is the average cost to replace a roof? ›
Material costs for 3-tab asphalt shingles run $75–$100 per square ($25–$35/bundle). Architectural/dimensional shingles cost $100–$180 per square ($33–$60/bundle). Labor typically adds $150–$300 per square, bringing total installed costs to $250–$500 per square. A 25-square roof (2,500 sq ft) typically costs $6,000–$12,500 installed. Metal roofing runs $400–$800 per square installed.
Do I need underlayment in addition to shingles? ›
Yes. Most building codes require roofing felt underlayment (15 lb or 30 lb felt, or synthetic underlayment) under asphalt shingles. One roll of 15 lb felt covers about 4 squares; 30 lb felt covers about 2 squares. Ice and water shield membrane is required in the first 24 inches from the eave in northern climates and around all penetrations. Budget an extra 10–15% of your shingle material cost for underlayment.

About this roofing calculator

This calculator determines roof area by multiplying the building footprint by the pitch multiplier (the secant of the pitch angle), then applies your waste factor and converts to roofing squares and bundle counts. It supports four common roof shapes: gable (two slopes), hip (four slopes), shed (one slope), and flat.

Don't forget these additional materials

Beyond shingles, a full roof job requires: underlayment felt or synthetic, ice and water shield at eaves and valleys, ridge cap shingles (one bundle covers about 35 linear feet of ridge), roofing nails, drip edge metal, and flashing at any chimneys or walls. Labor and disposal of old shingles typically double the material cost.