Inputs to result
Material area = sloped roof area × (1 + waste% ÷ 100); bundles = ceil(material area ÷ effective coverage per bundle).
Roofing
Roof Shingle Calculator
Convert measured sloped roof area into whole shingle bundles and roofing squares using product bundle coverage and waste allowance.
Enter actual sloped roof area, waste and the printed bundle coverage. The calculator shows roof squares and the rounded bundle order.
Calculation and worked example reviewed 2026-11-12. See our calculation methodology.
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Roofing
US UNITSEnter your measurements
YOUR ESTIMATE
40 shingle bundles13.2 squares incl. waste1,320 sq ft material at 33.33 sq ft/bundle.
Starter and cap shingles are separate products.
Formula and example
How this calculation works
This estimator converts your entered jobsite inputs (measured sloped roof area, shingle waste, effective coverage per bundle) into consistent US trade units, computes the exact geometric baseline first, and then applies any selected waste or order allowance so you can verify both numbers before purchasing materials.
How does the roof shingle calculator formula work?
Material area = sloped roof area × (1 + waste% ÷ 100); bundles = ceil(material area ÷ effective coverage per bundle).
(Roof Shingle Calculator)where:
- Measured sloped roof area – Entered in sq ft (default reference: 1200 sq ft);
- Shingle waste – Entered in % (default reference: 10 %);
- Effective coverage per bundle – Entered in sq ft (default reference: 33.33 sq ft);
Check the math
A 1,200 sq ft sloped roof with 10% waste needs 1,320 sq ft of material. At 33.33 sq ft per bundle, plan 40 bundles.
Quick lookup chart
Shingle Bundle & Roofing Square Reference by Sloped Roof Area
Assumes standard 3-bundle-per-square packaging (33.33 sq ft effective coverage per bundle).
| Sloped Roof Area | Net Squares | Bundles (10% Waste) | Bundles (15% Hip/Valley) |
|---|---|---|---|
| 1,000 sq ft | 10.0 squares | 33 bundles | 35 bundles |
| 1,200 sq ft | 12.0 squares | 40 bundles | 42 bundles |
| 1,800 sq ft | 18.0 squares | 60 bundles | 63 bundles |
| 2,400 sq ft | 24.0 squares | 80 bundles | 83 bundles |
Before you use this result
Bundle coverage differs by shingle product and exposure. Starter strips, hip/ridge caps, underlayment and complex cuts are separate line items.
- Always enter sloped roof surface area, not flat building footprint—use the Roofing Calculator if you need to apply a pitch multiplier first.
- Standard architectural and 3-tab shingles cover 33.33 sq ft per bundle (3 bundles/square), but heavyweight designer shingles may require 4 or 5 bundles/square.
- Order starter strip bundles and hip/ridge cap bundles separately; field shingle bundles do not include ridge or eave starter courses.
Questions answered
Calculator FAQ
How many bundles are in a roofing square?+
It depends on the selected product. A common 33.33 sq ft coverage means roughly three bundles per 100 sq ft square.
Should I enter footprint or roof surface?+
Enter measured sloped roof surface. Use a roof area calculation first if you only know the horizontal footprint.