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Roofing & Siding Calculators

Roof area, shingles, pitch, siding and gutters.

Roofing is measured in squares of 100 square feet, and the roof is always bigger than the house footprint because of the slope. The calculators here convert ground measurements and pitch into roof area, then into bundles of shingles, metal panels, underlayment, ridge cap and the trim around the edges.

Pitch is the key input. A 6/12 roof has 12 percent more surface than its footprint, a 12/12 roof has 41 percent more. Add 10 percent waste for a simple gable and 15 to 20 percent for hips, valleys and dormers, where every cut shingle is a partial loss.

All roofing & siding calculators

Roofing CalculatorCalculate roof area, roofing squares and how many bundles of shingles you need from your home's footprint and roof pitch. Includes underlayment and waste.Shingle CalculatorCalculate how many bundles of shingles you need from your roof area, plus ridge cap bundles, starter strip bundles and pounds of roofing nails, with waste included.Roof Pitch CalculatorCalculate roof pitch as x/12, the roof angle in degrees, slope percent and the pitch factor from a rise over run or from the total rise and building span.Metal Roofing CalculatorCalculate how many metal roofing panels, screws, closure strips and ridge cap you need from the eave length, panel length and panel coverage width, with waste.Rafter Length CalculatorCalculate common rafter length from the building span and roof pitch, including the ridge board deduction and overhang, plus the rise, cut angle and board length to buy.Siding CalculatorCalculate how many squares and boxes of vinyl siding you need from your house dimensions, plus starter strip, J-channel and corner posts, minus doors and windows.Gutter CalculatorCalculate how many gutter sections, downspouts, hangers, end caps and elbows you need from the total eave length, with an optional material cost per linear foot.Soffit and Fascia CalculatorCalculate soffit area and panels, fascia board length and 12 ft pieces, plus J-channel and F-channel for the eaves and gable rakes of a house from a few measurements.Roof Snow Load CalculatorCalculate the design roof snow load from the ground snow load, roof pitch, exposure and thermal factors using the ASCE 7 method, plus the total snow weight on the roof.

A typical project, in order

Carry each result into the next tool.

  1. 1Roof Pitch CalculatorFind the pitch and its area multiplier
  2. 2Roofing CalculatorRoof area and bundles from the footprint
  3. 3Shingle CalculatorBundles, starter, ridge cap and nails from roof area
  4. 4Rafter Length CalculatorRafter lengths for a new roof frame
  5. 5Gutter CalculatorSections, downspouts and hangers
  6. 6Soffit and Fascia CalculatorFinish the eaves
  7. 7Siding CalculatorSquares of siding for the walls below

Roofing & Siding questions

How many bundles of shingles per square?

Three for standard 3-tab and most architectural shingles. Some thick designer shingles need four or five; the wrapper states bundles per square.

How do I find my roof area without climbing on it?

Measure the house footprint including overhangs, then multiply by the pitch factor: 1.054 for 4/12, 1.118 for 6/12, 1.202 for 8/12, 1.414 for 12/12.

How much waste for a roof?

10% for a plain gable roof, 15 to 20% for hip roofs and roofs with valleys, dormers or skylights.