Free · Roofing calculators 🏠

Roof Surface and Shingle Bundles

Estimate sloped roof area, roofing squares and whole shingle bundles from dimensions and package coverage.

  • Formula & worked example
  • Private in your browser
  • No signup
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

In initial display units, Roof length 3, Roof width 4, Roof pitch (x:12) 0, One bundle roof coverage 3, Bundle size 20 gives Footprint area 12, Roof area 12, Shingle bundles 4, Shingles 80.

Sloped area = footprint × √(1+(pitch/12)²); bundles = ceil(area/bundle coverage); one square = 100 ft².

Worked example

Enter these known values and leave the other values blank.

Roof length
3 m
Roof width
4 m
Roof pitch (x:12)
0 :12
One bundle roof coverage
3 m² per bundle
Bundle size
20
Footprint area
12 m²
Multiplier
1
Roof area
12 m²
Roof area in squares
1.3 squares
Shingle bundles
4
Shingles
80

Assumptions and limitations

  • The footprint describes equal-pitch roof planes without openings, waste or overhang allowances. Pitch is limited to 0 through 12 rise per 12 run. Bundle coverage is the actual effective roof coverage, not raw shingle area.
  • Select compatible units and clear the quantity to solve before supplying the remaining measurements. Rounded purchase counts cannot uniquely recover a continuous dimension. Currency choices label amounts and do not convert exchange rates.

Common questions

How can I solve for a missing measurement?

Clear that field, then enter independent known values. Lock a known measurement to preserve it while changing another value. Procurement counts are rounded upward and cannot be reversed uniquely.

References

Enforce the stated physical and discrete input domains. Integer membership is checked with isInteger, so ordinary, tiny and large fractional counts are rejected even when tolerant floor equality would pass.

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