Roofing Calculator

Choose roof shape, size, overhang, and pitch. We estimate area, squares, shingles, underlayment, ridge caps, starter, drip edge, and cost.

What this roofing calculator does

Roof takeoffs usually start with a sketch, a handful of dimensions, and a quick pitch reading. This page turns those basics into the numbers you actually need to buy materials: total roof area and squares, shingle bundles, ridge-cap bundles, starter bundles, underlayment rolls, drip edge pieces, and optional sheathing sheets. You can work in US or metric units and toggle how you enter pitch (rise/run or degrees). We add waste on top of the sloped area and let you override ridge length when your geometry is unusual.

Prices are optional. If you enter bundle, roll, and piece pricing, we’ll output a clean cost summary you can drop into a quote. The CSV export helps when you’re collecting bids or comparing brands. For other project math, you might want the Square Footage Calculator, Lumber Calculator, or Paint Calculator—handy companions for the same job site.

Settings

Common: 5 to 15. Add more for complex roofs.

Roof geometry

US: feet (ridge direction)
US: feet (gable span)
US: inches. Applied to all sides.
US example: 6 in rise per 12 in run

Materials & pricing (optional)

Most architectural shingles: 3 bundles per 100 ft²
Gable default = length. Shed = 0. Hip ≈ shorter side. Edit if needed.
Typical 20 to 33 linear ft per bundle
Linear ft along eaves. Example 100 ft per bundle
US coverage per roll
Feet per piece
Simple count using plan area. 4×8 sheets.

How to use this roofing calculator

  1. Pick your units and waste. Work in US or metric and set a waste/overage percent. Complex roofs (valleys, dormers) often need more.
  2. Enter geometry. Length follows the ridge; width is the gable span. Add overhang (each side) and choose pitch as rise/run or degrees.
  3. Calculate. We compute plan area with overhang, apply the slope factor from your pitch, then add waste to reach order quantity.
  4. Add pricing (optional). If you know bundle/roll/piece prices, we’ll total shingles, ridge caps, starter, underlayment, drip edge, and optional sheathing.
  5. Export. Download the CSV for your job packet or vendor emails.

Estimating paint or interior work on the same job? Hop to the Paint Calculator or Square Footage Calculator. For framing takeoffs, the Lumber Calculator pairs well with this page.

Reading the results

Plan vs. roof area. Plan area is the footprint with overhangs included. Roof area multiplies plan by the slope factor (1/cos(θ) or √(rise² + run²) / run), then applies your waste percent for ordering.

Squares and bundles. A square is 100 ft². We multiply squares by your “bundles per square” (usually 3) and round up to whole bundles.

Linear items. Eaves determine starter; perimeter drives drip edge; the ridge value is editable, because hips and intersecting ridges can change totals.

Costs. When you enter prices, we subtotal each category and show a grand total. Taxes, delivery, and accessories (vents, flashing) aren’t included, so pad accordingly.

FAQ

What’s a good waste percentage?

Simple gables often land around 5–10%. Hips, valleys, and dormers push you toward 10–15% or more. If you’re mixing brands or colors, add extra for future repairs.

Why does the ridge default change by roof type?

Gables have a ridge equal to the length. Sheds have none. Hips often have a shorter primary ridge, so we start with the shorter side and let you override.

How do I enter pitch in metric?

Use the same units for rise and run (e.g., centimeters over centimeters). The ratio is unitless; we convert only where needed for area and linear totals.

Does this include valleys, flashing, or vents?

No. This is a straight materials estimate for the field and edges. Always add accessories per your local code and the shingle manufacturer’s instructions.