Roofing Shingle Calculator

Estimate sloped roof area, roofing squares, shingle bundles and underlayment from footprint, rise per 12 inches and your waste allowance. Calculate it clearly with Figur.

Convert roof footprint and pitch into shingle quantities

Measure the horizontal footprint in feet, including overhangs you want covered. A pitch of 6/12 means 6 inches of rise for every 12 inches of horizontal run. Multiply length × width by √(1 + (pitch ÷ 12)²) for sloped area, then by (1 + waste ÷ 100) for order area. Divide by 100 for roofing squares. The calculator rounds up squares × 3 to shingle bundles and squares ÷ 4 to underlayment rolls; it does not round squares before those conversions.

Method and assumptions

Roof area = length × width × √(1 + (pitch ÷ 12)²). Order area = roof area × (1 + waste ÷ 100). Bundles = round up(order area ÷ 100 × 3); rolls = round up(order area ÷ 400).

  • One pitch applies to the entire rectangular horizontal footprint. Measure sections separately when pitches differ.
  • Every square is 100 sq ft; packaging is fixed at 3 bundles per square and 400 sq ft per underlayment roll. Verify your product's coverage.
  • Waste is only the percentage entered. Valleys, hips, starter strips, ridge caps, flashing, fasteners and labor are not counted separately.
  • This estimates materials, not roof structure, code compliance or a contractor price.

Planning takeoff, not a binding bid, structural design or engineering advice. Confirm field measurements, product coverage, installation requirements and supplier quantities before buying.

Sources and references

The result uses your inputs and the tool's documented assumptions; it does not fetch current prices, rates or products.

Worked example

A 40 × 30 ft horizontal roof footprint has a 6/12 pitch and 10% waste.

1,200 × √1.25 = 1,341.64 sq ft; × 1.10 = 1,475.80 sq ft to order, or 14.758 squares. Round up 44.274 to 45 bundles and 3.690 to 4 rolls.

Frequently asked questions

Is footprint area the same as roof area?

Only on a flat roof. A 6/12 pitch multiplies horizontal area by about 1.118, so entering measured sloped area as the footprint would count pitch twice.

Does it count ridge caps and starter shingles?

No. Budget those separately and confirm bundle and roll coverage with the supplier; the fixed packaging assumptions may not match your product.

How should I handle multiple roof pitches?

Calculate each horizontal section with its own pitch and waste allowance. Add unrounded order areas before converting to shared package quantities if buying the same product.

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