Free tool
Roofing Calculator
Convert roof footprint area and pitch into squares, shingle bundles, underlayment rolls, and nails. Matches the math in Drevanto's certified asphalt-shingle Instant assembly.
Result
Results updated.
| Squares (100 sq ft) | 22.0squares |
|---|---|
| Shingle bundles (3 per square) | 66bundles |
| Underlayment (1,000 sq ft rolls) | 3rolls |
| Roofing nails | 44lb |
| Ridge vent | 40linear ft |
Formula
- squares = roof area × (1 + waste) ÷ 100
- bundles = ceil(squares × 3)
- underlayment rolls = ceil(roof area × (1 + waste) ÷ 1,000)
- nails = ceil(squares × 2 lb)
- ridge vent = ridge length entered
Assumptions
- Architectural shingles packaged 3 bundles per square.
- Synthetic underlayment in 1,000 sq ft (10 square) rolls.
- 2 lb of coil roofing nails per square.
What this does not cover
- Steep slopes, valleys, and hips increase waste beyond a flat percentage — verify with a measured takeoff.
- Starter strip, drip edge, flashing, and ice/water membrane depend on eave, rake, and penetration measurements not entered here.
Planning aid only — not a quote. Quantities use documented rules of thumb; verify against your plans, local codes, site conditions, and real supplier pricing before ordering or bidding.
Methodology
Roof area is footprint area times a pitch multiplier: rise over 12, squared, plus one, square-rooted. A 6/12 roof multiplies area by about 1.118. Shingles are ordered by the square (100 sq ft), three bundles to a square, with your waste allowance applied — starter and ridge add roughly one bundle per 80 linear feet of eave, rake, and ridge combined. Underlayment rolls assume 400 sq ft of coverage each, and nails run about 2 lb per square for standard four-nail application.
Worked example: 2,000 sq ft footprint at 6/12, 10% waste
- Roof area = 2,000 × 1.118 = 2,236 sq ft
- Squares = 2,236 × 1.1 ÷ 100 = 24.6 → 25 squares → 75 bundles
- Underlayment = ceil(2,460 ÷ 400) = 7 rolls; nails ≈ 50 lb
Frequently asked questions
How do I measure roof pitch without climbing?
Measure from the attic: hold a level 12 inches against a rafter and measure the rise. Or count the pitch from gable-end photos. Never estimate pitch from the ground on a steep roof.
Does this handle tear-off?
It sizes materials for the new roof only. Tear-off labor, disposal, and deck repair are separate lines — the Drevanto certified roof assembly includes them as editable scope items.
Why three bundles per square?
That is the standard packaging for architectural asphalt shingles. Always confirm the bundle-to-square ratio on the specific product.
Certified benchmark · 2026-08-21
In 520 certified profile-mode generations across 26 supported Instant assemblies on Windows (profile/AOT) and an Android API 36 emulator, supported jobs became editable estimates in a median of 0.028 seconds (rounded); the measured 95th percentile was 48.008 milliseconds (approximately 0.048 seconds), with 0 generative-AI provider calls.
- median, supported jobs
- 0.028 sec
- certified generations
- 520
- supported assemblies
- 26
- failures · 0 AI provider calls
- 0
Certified supported jobs only. Editable output; contractor pricing and field verification remain in control. Full methodology and results
See it run on your own jobs
The private Drevanto beta is the real, editable product — not a website demo. Apply, and we will follow up by email.