Roof quantities, not structural design

A roof is more than one rectangle.

Check mixed pitches before buying bundles ↓

Build a material worksheet from non-overlapping roof faces, exact package coverage and actual supplier quotes. Keep measured area, allowance and purchased coverage visible.

Reviewed October 8, 2026Free · browser-side math
Measure safely. Do not climb a roof to use this planner. Use plans or measurements supplied by a qualified professional. This is not a roof design, installation specification, structural check or code approval. Valleys, penetrations, flashing, fasteners, ventilation, tear-off and disposal are not automatically sized.

1. Roof faces

Defaults demonstrate a hypothetical 50 × 30 ft gable: two separate 50 × 15 ft horizontal projections at 6:12. Never enter the whole footprint twice.

2. Product coverage

The default is a mathematical three-bundles-per-square example, not a universal product specification. Different products can cover less or more. Pool only the same compatible product; separate rounding may increase the purchase.

Optional accessories

Enter installed coverage after required laps and layers. Roll label area alone may overstate coverage. Layer and water-barrier requirements are outside this planner.

Zero length means omitted, not unnecessary. Confirm installation edges and effective package coverage with the manufacturer. All defaults are editable teaching values.

3. Enter quotes (USD)

Leave unknown prices blank. Zero is a deliberately entered zero, not a market estimate.

Tax applies to priced material rows only. Add other applicable taxes, tear-off, disposal, flashing and permits under Other using confirmed quotes.

Your quantity worksheet

sq ft measured roof
roofing squares before allowance
sq ft with shingle allowance
sq ft listed bundle coverage purchased

Face inventory, not a scaled roof plan. Listed coverage above measured area includes allowance and package rounding; it is not predicted reusable waste.

Roof facePitch factorSurface sq ftWith allowance
Material / formulaBuy quantityEntered cost
Entered-price estimate

Supplier checks before purchasing

  • Verify each non-overlapping face, pitch and overhang from safe measurements.
  • Confirm exact installed coverage, lap requirements and compatible accessories.
  • Account separately for valleys, flashing, penetrations, ventilation and fasteners.
  • Check roof suitability, installation requirements, permits and structural concerns professionally.
  • Confirm taxes, delivery, returns, quote date, tear-off and disposal.
Read the full worked example →

How the quantities are calculated

Projected rectangular face: (length + combined length extensions) × (horizontal run + combined run extensions) × √(1 + (pitch ÷ 12)²). Triangular projected face: base × perpendicular height ÷ 2 × pitch factor. A measured sloped face uses its surface dimensions without another pitch adjustment. Add non-overlapping faces, apply the entered allowance and round to complete product packages.

Accessories use separately entered installed lengths; this tool does not infer them from roof area. Product coverage controls purchasing. See GAF’s explanation of squares and bundles and verify your exact product instructions.

Single-footprint shingle calculator · Roof-area methods · Separate rafter layout aid

Original measurement check · October 17, 2026

Different pitches need separate area calculations

Two horizontal projections of 750 sq ft at 6:12 and 4:12 total approximately 1,629.095 sq ft of sloped surface. With 10% extra and exactly 100 ÷ 3 sq ft per bundle, buy 54 bundles. Assuming both faces are 6:12 instead gives 56 bundles. This comparison isolates the pitch assumption; it does not choose an allowance or product for your roof.

Face A: 750 sq ft6:12 pitchFace B: 750 sq ft4:12 pitchHorizontal projections, not already-measured sloped areas

Use plans or measurements from qualified providers; do not climb to obtain inputs. Do not apply pitch to an area already measured on the sloped surface. Include external overhangs once and avoid overlaps. These examples pool one compatible field-shingle product across both faces; they do not include starter, cap, flashing or underlayment.

Resolve a supplier-area mismatch in this order
  1. Ask whether each number is horizontal projection, sloped surface, or material area after allowance. Those are three different quantities.
  2. Match the counted faces, pitch, external overhangs and exclusions. Do not assume building floor area equals roof projection.
  3. Separate the allowance from the measurement, then confirm the exact installed package coverage. Bundles are not roofing squares.
  4. Compare the same accessories, taxes, disposal and labor scope. A smaller bundle count alone does not establish a better quote or a suitable roof system.

A roofing square is 100 sq ft; package counts vary by product. See GAF’s explanation. The coverage used here is an exact hypothetical arithmetic input, not a claim about a particular shingle.

Enter separate roof faces and quote items · Inspect the calculation checks