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Blueprint Calc

Roofing Calculator

Size a roof replacement: squares, shingle bundles, underlayment, nails, and a total installed-cost estimate. Works for asphalt, metal, cedar, and slate.

How much roofing material do I need?

Default: 1,800 sq ft footprint, standard 5-8/12 pitch, architectural asphalt.

You need
  • Roof area
    23 squares (2,277.00 sq ft)
    1,800 sq ft footprint × 1.15 pitch multiplier + 10% waste
  • Shingle bundles
    69 bundles
    Asphalt: ~3 bundles per square. Metal/cedar/slate ship as panels or per-piece.
  • Underlayment rolls
    6 × 400 sq ft rolls
    Synthetic underlayment covers 200-400 sq ft; 15# felt ~400 sq ft.
  • Roofing nails
    57 lb
    ~2.5 lb per square at 4 nails per shingle. Use 6 nails in high-wind zones.
  • Material cost estimate
    $3,985
    23 squares × ~$175/sq (25-30 years lifespan)
  • Total installed estimate
    $9,677
    Material + labor at $250/sq. Regional variance: ±30%.

Roofing is almost never a DIY job. Hot asphalt, 2-story fall risk, insurance claim complexity, and the warranty requirement for licensed installers all point to hiring a pro. Use this calculator to sanity-check contractor quotes.

Roofing tools and supplies

Prices approximate · Links go to retailer search results

Product links go to Home Depot search results — pick the best match for your project. Prices shown are rough averages.

How we calculated it

Roofing math has two steps: turn your footprint into actual roof surface (pitch multiplier), then turn roof surface into material units (bundles, rolls, nails).

Pitch multiplier: the factor by which a sloped surface exceeds its horizontal projection. A perfectly flat roof has a 1.0 multiplier (footprint = roof). A 6/12 pitch — the most common US residential slope — multiplies by ~1.15. A 12/12 pitch (45°) multiplies by ~1.41.

Shingle bundles: a bundle covers ~33.3 sq ft — 3 bundles = 1 square (100 sq ft). A 25-square roof needs 75 bundles.

This calculator covers asphalt-shingle math. Metal roofing is sold in panels (different math), cedar shake in squares by grade, and slate per piece. The square output is valid for all — talk to your supplier about their specific packaging.

Frequently asked questions

How many squares is my roof?
A "square" is roofing industry shorthand for 100 sq ft. A 2,000 sq ft house with a standard 6/12 pitch has about 23 squares of roof (footprint × 1.15 pitch multiplier ÷ 100). The exact number depends on pitch and any valleys or hips.
How many bundles of shingles per square?
Asphalt shingles cover ~33.3 sq ft per bundle, so you need 3 bundles per square. A 25-square roof needs 75 bundles. Add 10-15% for waste on simple roofs, 20% on complex cut-up roofs.
How much does a new roof cost in 2026?
US 2026 averages: asphalt $5,000-12,000 for a typical 1,800 sq ft home. Metal: $15,000-30,000. Cedar shake: $15,000-25,000. Natural slate: $25,000-60,000. Regional variation is 30%+ — get 3 quotes.
Do I need to remove old shingles before installing new ones?
Code allows up to 2 layers of asphalt shingles. Going to a 2nd layer saves ~$1,500 on labor but shortens the next roof's lifespan (heat builds up underneath), and you can never see what damage lives under the old shingles. Full tear-off is the industry recommendation.
What pitch is my roof?
Measure rise over 12 inches of run. A roof that rises 6" in 12" run is "6/12". Use a level with a 1 ft measurement marked, or just measure the vertical gain over a 12" horizontal span. Most US residential roofs are 5/12-8/12.
Can I install shingles myself?
Legally, in most states, yes — but realistically no. Roofing is 2-story fall risk, requires specific safety harness setup, and manufacturer warranties usually require licensed installation. Labor is typically 40-60% of the total bill — hire the pro.
How long does a roof last?
3-tab asphalt: 15-20 years. Architectural asphalt: 25-30 years. Metal: 40-70 years. Cedar: 30-40 years with maintenance. Slate: 75-100+ years. Actual lifespan depends heavily on climate, ventilation, and install quality.
Do I need new underlayment?
Yes, on a full tear-off replacement. Old 15# felt is typically shot; synthetic underlayment is now the standard (tear-resistant, UV-tolerant if exposed temporarily). Ice-and-water shield is required in cold climates along eaves, valleys, and around penetrations.
How many nails per shingle?
4 nails per shingle is standard. 6 nails per shingle is required in high-wind zones (coastal, Florida, Gulf) and strongly recommended on steep roofs. Roughly 2.5 lb of coil or hand-drive nails per square.
When is the best time to replace a roof?
Late spring through early fall. Avoid installing below 40°F (shingles don't seal properly) or above 90°F (shingles scuff easily). In 100-degree markets crews start at 5 AM for that reason.

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See also

Related terms

Plain-English definitions for the terms used in this calculator.

waste factor
An over-order multiplier to account for cuts, damage, errors, and touch-ups. 10% is standard for simple jobs; 15-20% for complex layouts (diagonal tile, cathedral ceilings, rough subgrades).
linear foot vs square foot vs cubic foot
Linear foot = 12 inches in a single dimension (trim, pipe, lumber length). Square foot = a 12×12" area (tile, flooring, drywall, paint). Cubic foot = a 12×12×12" volume (mulch, gravel, concrete).