Roofing Calculator is an online tool to roofing installation area, estimate the cost of installation, calculate number of squares required, estimate how many bundles of 3-tab asphalt shingles and number of rolls of 15lb felt are needed for new roof. Add the price per square of materials to get an estimated material cost.

To find the squares, divide the overall roof area by 100 and then round up.

Roofing Area = Length x Width x Roof Pitch

Roof pitch is the measurement of a roof's vertical rise divided by its horizontal run. It is often compared to slope, but is not exactly the same. Roof pitch is a determining factor for cost of the roof, as well as the roof area, and the type of materials used.

The average bundle of shingles covers 33.3 ft^{2}, so three bundles of shingles are needed per square.

Total bundles of 3-tab asphalt shingles required: Total Installation Area / 33.3

Roofing felt is sold by the roll. The average roll of 15-pound roofing felt covers about 400 ft^{2}, or 4 squares

Number of Rolls = Area / 400

Total Cost = Number of Squares x Price per Square

Pitch | Angle | Multiply By | Pitch | Angle | Multiply By | |
---|---|---|---|---|---|---|

0/12 | 1 | |||||

1/12 | 4.8° | 1.003 | 2/12 | 9.5° | 1.014 | |

3/12 | 14° | 1.031 | 4/12 | 18.4° | 1.054 | |

5/12 | 22.6° | 1.083 | 6/12 | 26.6° | 1.118 | |

7/12 | 22.6° | 1.158 | 8/12 | 26.6° | 1.202 | |

9/12 | 36.9° | 1.250 | 10/12 | 33.7° | 1.302 | |

11/12 | 42.5° | 1.357 | 12/12 | 45.6° | 1.414 | |

13/12 | 47.3° | 1.474 | 14/12 | 49.4° | 1.537 | |

15/12 | 51.3° | 1.601 | 16/12 | 53.1° | 1.667 | |

17/12 | 54.8° | 1.734 | 18/12 | 56.3° | 1.803 | |

19/12 | 57.7° | 1.873 | 20/12 | 59.0° | 1.944 | |

21/12 | 60.3° | 2.016 | 22/12 | 61.4° | 2.088 | |

23/12 | 62.4° | 2.162 | 24/12 | 63.4° | 2.236 |