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Roofing Tools

Roofing Material Calculator

A roofing material takeoff lists everything a shingle roof needs besides the shingles: underlayment, ice and water barrier, drip edge, starter, ridge cap, and nails. Enter a simple gable house or your measured roof lengths. Every coverage figure is editable and comes from a code section or a manufacturer data sheet.

Roof measurements

Simple rectangular gable roof, ridge along the length. Hip roofs and dormers: use measured lengths.

Required by the IRC where your local code lists a history of ice dams. Check with your building department.

One roll width down each valley.

Coverage and code assumptions

Defaults: IRC R905.1.2 (24 in), IRC R905.2.6 minimum of 4 nails, CertainTeed DiamondDeck net coverage, GAF WeatherWatch 2-square roll. Laps follow GAF’s instructions (3 in side, 6 in end, 10 ft sheets).

Results

Shingle bundles (field + starter + ridge cap)

54

16.53 squares with waste, plus the materials below

Field shingle bundles
50
Starter strip bundles
2
Hip & ridge cap bundles
2
Synthetic underlayment rolls
2
Ice & water barrier rolls (2 eave courses)
3
Drip edge pieces (156 ft)
16
Roofing nails (field shingles)
4,232

A planning takeoff, not an order list from a supplier. Flashing, vents, pipe boots, sealant, and nails for starter, ridge, and drip edge are not included. Product data sheets and local code decide the final quantities.

How this was calculated
  1. Roof area = plan area × pitch multiplier 1.118 = 1,502.6 sq ft
  2. Eaves = 2 × 42 = 84 ft; rakes = 4 × 17.89 = 71.6 ft
  3. Field bundles = 16.53 squares (with 10% waste) × 3 → 50
  4. Starter = (eaves + rakes) 155.6 ft ÷ 120 → 2 bundles
  5. Ridge cap = 42 ft ÷ 25 → 2 bundles
  6. Underlayment = 1,503 sq ft ÷ 937.5 → 2 rolls
  7. Ice barrier width = (12 + 24) in × slope = 40.2 in
  8. Courses = 1 + ⌈(40.2 − 36) ÷ (36 − 3)⌉ = 2
  9. Membrane = (504 eave + 0 valley) × 10 ÷ (10 − 6/12) = 531 sq ft → 3 rolls
  10. Drip edge = 155.6 ft ÷ (10 − 2/12) → 16 pieces
  11. Nails = 16.53 sq × 64 shingles → 1058 × 4 = 4,232

Worked example

The same 40 × 30 ft gable house as the Roof Square Calculator: 12 in overhangs, 6/12 pitch, 10% waste, ice barrier at the eaves, no valleys.

Roof area 1,503 sq ft; eaves 84 ft; rakes 71.6 ft; ridge 42 ft
Shingles: 50 field + 2 starter + 2 ridge cap = 54 bundles
Underlayment: 1,503 sq ft ÷ 937.5 = 2 rolls
Ice barrier: (12 + 24) in × 1.118 = 40.2 in → 2 courses
  504 sq ft × 10 ÷ 9.5 (end laps) = 531 sq ft → 3 rolls
Drip edge: 155.6 ft ÷ (10 − 2/12) ft = 16 pieces
Nails: 1058 shingles × 4 = 4,232

How each quantity is calculated

shingles        = same math as the Shingle Bundle Calculator (3 bundles per square)
starter         = (eaves + rakes) ÷ starter feet per bundle
underlayment    = full roof area ÷ net roll coverage
ice width (in)  = (overhang + 24 in inside wall) × pitch multiplier
                  (at least 36 in along the slope at 8/12 and steeper)
courses         = 1 + ⌈(width − roll width) ÷ (roll width − 3 in side lap)⌉
ice membrane    = (eaves × courses × 3 ft + valleys × 3 ft) × sheet ÷ (sheet − 6 in end lap)
drip edge       = (eaves + rakes) ÷ (piece length − 2 in lap)
nails           = field shingles × nails per shingle

The ice barrier rule is a horizontal distance (24 in past the inside of the exterior wall), so the calculator converts it to a distance along the slope. [1] GAF’s roll coverage excludes laps, so lap allowances are added separately. [2] [3] Underlayment is budgeted for the whole deck even where ice barrier replaces it, because it laps onto the membrane and the saving is usually less than a roll.

Limitations

  • The gable-house option assumes one rectangular roof with one pitch and the ridge along the length. Hip roofs, dormers, and additions need measured lengths.
  • Whether an ice barrier is required depends on your local code (IRC Table R301.2) and the shingle manufacturer. Some jurisdictions require more than the 24 in minimum.
  • Coverage figures are for specific products (GAF, CertainTeed). Other brands and felt underlayment cover different areas; replace the defaults with your product’s data sheet.
  • Drip edge is counted in 10 ft pieces, which is an assumption about what suppliers stock, not a sourced figure. Nail counts cover field shingles only.
  • Flashing (step, wall, chimney), vents, pipe boots, decking repairs, and sealant are not included. This is a planning list, not a supplier order or an estimate of cost.

Common scenarios

  • Cold-climate roof with deep overhangs: a wider overhang pushes the ice barrier past one 36 in course. Two courses with a 3 in lap cover only 69 in, so a third course starts beyond that.
  • Steep roof (8/12 or more): the IRC requires at least 36 in along the slope, even if the 24 in inside-wall rule would give less. [1]
  • High-wind area: many manufacturers require 6 nails per shingle there. Change nails per shingle in the assumptions. [8]
  • Checking an insurance estimate: use measured lengths from the estimate’s roof report, then compare line items such as drip edge, starter, and ice and water barrier. Missing items are worth asking about; the code or manufacturer may require them.

Common questions

How is this different from the Shingle Bundle Calculator?

Shingle Bundle counts only shingle bundles. This tool adds underlayment, ice and water barrier, drip edge, and nails, and it can work from house dimensions instead of a known roof area.

Is ice and water shield required?

The IRC requires an ice barrier where local code designates a history of ice damming along the eaves. It extends from the eave to at least 24 in inside the exterior wall, and at least 36 in along the slope on 8/12 and steeper roofs. Ask your building department whether it applies where you live.

How much does a roll of underlayment cover?

It depends on the product. CertainTeed DiamondDeck is 1,000 sq ft gross and about 937.5 sq ft net after laps, which is the default here. Felt rolls cover much less, so enter your product’s net coverage.

How many nails per shingle?

The IRC minimum is the manufacturer’s count but not fewer than four per strip shingle. Owens Corning says four is adequate in most cases, with six where slope or code requires it.

Is drip edge required?

Under IRC R905.2.8.5, drip edge is required at the eaves and rakes of shingle roofs, with adjacent pieces overlapped at least 2 in.

Related tools

Sources and methodology

Code values come from the IRC (read on a state-adopted edition, since the ICC site did not render). Coverage values come from manufacturer data sheets for specific products and are editable. No cost figures are used on this page. All sources retrieved 2026-09-24.

This tool provides an educational estimate only. Insurance companies, contractors, and building officials may calculate these figures differently depending on policy language, property condition, local pricing, and applicable codes.

Disclaimer: Calculators and information on this site are provided for educational and estimating purposes only. Results do not determine insurance coverage, claim payments, repair requirements, or professional recommendations.