Roofing Calculator

Calculate roofing materials for any project. Choose from 5 material types — asphalt, architectural, metal, wood shake, or clay tile. Get squares, shingle bundles, underlayment, drip edge, ridge cap, nails, and cost estimate.

🏠 Roofing Calculator

Roofing Material

Roof Length (ft)

Roof Width (ft)

Roof Pitch

Waste Factor (%)

Cost per Square ($)

Area

Footprint Area1,200.00 sq ft

Actual Roof Area1,264.80 sq ft

Total (+ waste)1,391.28 sq ft

Roofing Squares13.9 squares

Materials

Shingle Bundles42 bundles

Underlayment Rolls4 rolls (400 sq ft)

Drip Edge154 linear ft

Ridge Cap33 linear ft

Roofing Nails35 lbs

Cost

Estimated Material Cost$1,808.66

💡 How to Calculate Roofing Materials

Roofing is measured in ‘squares’ — one square equals 100 square feet of roof area. To convert ground-level (footprint) measurements to actual roof area, multiply by a pitch correction factor. A 4:12 pitch multiplies by 1.054; a 12:12 (45°) pitch multiplies by 1.414.

Standard asphalt shingles come in bundles, with 3 bundles per square (100 sq ft). Underlayment (felt or synthetic) comes in rolls covering ~400 sq ft. Don’t forget drip edge (roof perimeter), ridge cap (ridge length), and roofing nails (~2.5 lbs per square). Always add 10% for waste.

Find your roof pitch with our roof pitch calculator. Calculate area with our square footage calculator. For metal roofing, see our metal roofing calculator.

Roof Pitch Correction Factors

Roof pitch determines how much larger the actual roof area is compared to the footprint you measure from the ground. Use this table to convert:

Pitch	Multiplier	Angle (°)	Classification
0:12	1.000	0°	Flat
2:12	1.014	9.5°	Low slope
4:12	1.054	18.4°	Low slope
6:12	1.118	26.6°	Conventional
8:12	1.202	33.7°	Conventional
10:12	1.302	39.8°	Steep
12:12	1.414	45°	Very steep

Formula: Actual roof area = footprint area × pitch multiplier. Most US residential roofs are 4:12 to 8:12.

Roofing Material Types

Material	Cost / Square	Installed / Sq	Lifespan	Best For
Asphalt 3-Tab	$70–$120	$250–$400	15–20 years	Budget roofs, rentals
Architectural (Dimensional)	$100–$160	$350–$500	25–30 years	Most residential homes
Metal Panels (Standing Seam)	$300–$500	$600–$1,200	40–70 years	Long-term, hail/wind areas
Wood Shake / Shingle	$350–$500	$600–$900	20–40 years	High-end, rustic aesthetic
Clay / Concrete Tile	$600–$1,000	$1,000–$1,800	50–100+ years	Southwest, Mediterranean style

Roofing Components Guide

Shingles / Panels

The primary roof covering. Asphalt shingles are sold in bundles — 3 bundles = 1 square (100 sq ft). Metal panels are sold by the sheet or linear foot. Wood shakes are sold in bundles covering approximately 25 sq ft each (4 bundles per square).

Underlayment

A waterproof barrier between the shingles and the roof deck. Types include:

15 lb felt (tar paper): Budget option, covers ~400 sq ft per roll. Being replaced by synthetics.
30 lb felt: Heavier, more durable. ~200 sq ft per roll. Required for some metal roofs.
Synthetic underlayment: Lighter, stronger, and water-resistant. ~1,000 sq ft per roll. Industry standard for new construction.

Ice & Water Shield

Self-adhering membrane applied at eaves, valleys, and around penetrations. Required by code in cold climates. Apply from the eave up to at least 24 inches past the interior wall line.

Drip Edge

Metal flashing installed along the eaves and rakes (sides) of the roof. Prevents water from wicking under the shingles. Sold in 10-ft strips — divide your roof perimeter by 10 and add 10% for overlap.

Ridge Cap

Pre-bent or hand-cut shingles applied along the ridge (peak) of the roof. Sold by the linear foot or in bundles covering ~33 linear feet. Provides a finished look and ventilation gap for ridge vents.

Roofing Nails

Use 1¼-inch galvanized roofing nails for standard shingles. Plan ~2.5 lbs of nails per square. High-wind zones may require 6 nails per shingle instead of 4, increasing nail consumption by ~50%.

Roof Replacement Cost (2025 US Pricing)

Cost Component	Typical Range
Asphalt shingles (architectural)	$100–$160 per square (material)
Underlayment (synthetic)	$50–$75 per roll (1,000 sq ft)
Drip edge	$1–$3 per linear foot
Ice & water shield	$50–$100 per roll (75 sq ft)
Ridge cap shingles	$30–$60 per bundle (33 lin ft)
Tear-off (old roof removal)	$100–$150 per square
Professional labor	$150–$300 per square
Average 20-square roof (architectural, full replacement)	$8,000–$15,000 total

Does Your Roof Need Replacing?

Age: Asphalt roofs over 20 years old are approaching end of life even without visible damage.
Curling or buckling shingles: Shingles that curl at the edges or buckle in the center are failing.
Missing granules: Check gutters for large granule deposits — this means the shingles are degrading.
Daylight through the roof deck: If you see light in the attic, water is getting in.
Sagging roof deck: A sagging roof indicates structural damage — get a professional inspection immediately.

A 30×40 ft roof at 4:12 pitch = 1,200 sq ft footprint × 1.054 = 1,265 sq ft actual. With 10% waste = 1,391 sq ft = 13.9 squares = 42 bundles. Underlayment: 4 rolls. Drip edge: 154 linear ft.