How to use this calculator
- Enter Roof squares.
- Enter Waste in % — or tap a preset badge to auto-fill a typical value.
- Press Calculate. The highlighted row is your order quantity; the note beneath it translates the number into real-world terms.
Formula & constants
Three bundles of standard 3-tab or architectural shingles cover one square (100 sq ft). Squares × 3 × (1 + waste) = bundles. A 20-square roof at 15% waste needs 69 bundles. Every default in the fields above is editable — when your supplier’s spec sheet lists a different density, coverage rate or price, enter that number instead. The waste and compaction allowances follow common trade practice; see our methodology page for the derivation of each formula and the standards it references.
Where this fits in the project
Roof takeoffs start from the footprint corrected by pitch: get true area from the roof square footage calculator, convert to squares, then to shingle bundles or metal panels. Size gutters from the same perimeter measurement.
How this connects to your project
No quantity stands alone — each material in the chain depends on the ones around it. These are the planning steps that pair with the shingle calculator:
- Roofing Calculator — Shingles are the primary roofing material.
- Roof Square Footage Calculator — Shingle quantity depends on roof area in squares.
- Roof Pitch Calculator — Steeper pitches need more shingles due to waste.
- Roofing Cost Calculator — Shingle material is the main roofing cost.
- Metal Roofing Calculator — Compare shingle vs metal roofing.
- Gutter Calculator — Gutters are installed after shingles.
Frequently asked questions
How many bundles in a square?
Three for standard shingles; some heavyweight architectural lines run four — check the wrapper coverage.
Do I need starter and ridge extra?
Yes — starter strip along eaves/rakes and ridge caps are separate line items beyond the waste factor.
Last verified: — prices reflect current national averages. See our methodology.
Estimates are for planning. Material densities, coverage rates and prices vary by region and supplier — confirm final quantities before ordering, and check local code where structural or electrical work is involved.