Roofing Waste Factor Calculator
Every cut at a rake, hip or valley turns part of a shingle into scrap. The waste factor is the extra you order so the crew does not run short.
Waste factor and order quantity
Typical waste factors
| Roof | Typical waste | Why |
|---|---|---|
| Shed or single plane | 3–5% | Cuts only at the rakes |
| Simple gable | 7–10% | Rake cuts on both ends |
| Gable with dormers or a wing | 10–12% | Valleys and dormer cheeks |
| Hip roof | 12–15% | Every course is cut at two hips |
| Cut-up / complex | 15–20%+ | Many hips, valleys, turrets and short runs |
The extra-footage term is a RoofGenius rule of thumb, not an industry standard: each foot of hip or valley line costs roughly one square foot of shingle in offcuts. Pros who track their own jobs should replace the 1 sq ft default with their own number.
Worked examples
Don't double-count
- Starter and hip & ridge cap are usually separate products. Do not include their footage in the waste.
- Some measurement reports already list a "suggested waste" area. Check before adding your own.
- Waste applies to material, not to labor. Contractors usually price labor on the measured area.
Frequently asked questions
What is a normal waste factor for shingles?
About 10% for a simple gable roof and 15% for a hip roof. Complex, cut-up roofs can need 20% or more.
Why do hip roofs need more waste?
Every shingle course on a hip roof is cut at the hip lines on both ends, and the offcuts are usually too small to reuse.
Is waste factor included in roof area?
No. Roof area is the measured surface. Waste is added on top to get the quantity to order.
Last reviewed 2026-10-10. Results are estimates for planning; confirm quantities with your supplier and requirements with your local building code and the manufacturer's instructions.