Roofing Calculator

By HomeAdvisor

Updated March 23, 2020



Nominal Roof Size (in sq. ft.)
Roof Pitch

Tips on Measuring for Roofing

To accurately calculate the area of your roof, you must first determine its slope, or pitch. Roof pitches are described in terms of rise and run. The run is the distance from the outside edge of a perimeter stud wall to the center of the house. The rise is the distance from the top of a stud wall to the peak of the roof.

A roof’s pitch is determined by how much it rises for every foot it runs. Thus, a moderate 6 in 12 roof pitch means the roof rises 6 inches for every 12 horizontal inches it runs. A 12 in 12 pitch is a steep, 45-degree angle roof.


  1. William McKleroy, July 7:

    I am roofing the house trailer and need to know how many packs of shingles needed,

  2. Cecil Venturella, March 3:

    1square of roofing covers 100 square feet of roof a bundle is 1/3 of a square. Get the square footage of roof and divide it by 100 and it will give the number of squares you need and for every decimal number over 3 buy a bundle to achieve the amount of material. Hope it helps

  3. Alan J Warshawer, August 13:

    This in not applicable to a flat roof

  4. Jerrold Simpson, August 31:

    You should not put shingles on a flat roof. If you are going to use shingles, build a pitched roof over the mobile home. The dead air space between the metal roof and shingle roof will work as a barrier to dissipate heat.
    You should use rolled roofing on a flat roof, over lap 1/2 the width of the rolled roofing.
    A mobile home roof should not be flat. It should have a curved roof. Rolled roofing is best on a mobile home anyway.

  5. richard laham, September 5:

    what about peaks and valleys? Is there a standard allowance for scrap?

  6. Tee, September 10:

    im wanting to do a metal roof on my 16 x 80 mobile home. How much metal tin will I need as well as the thickness? Thanks in advance.

  7. Alesia, October 7:

    According to your calculator my “Actual Square Feet of House” is 4807.5 &
    “Numbers of Squares Needed” is 53.
    The numbers I used are based on the proposal from my roofer: 3698 sq ft with predominant 10/12 pitch.
    The problem is my roofer is saying only 41 squares are needed. Can you help me reconcile the difference?

  8. Shana Dockery, October 30:

    How much metal would I need to put on a 76inch foot long by 28 inch wide mobile home roof

  9. ZsaZsa, March 21:

    My roofer told me my roof is 13 square, how many bundles of shingles will I need? How would I calculate for the underlayment (tar paper & weather barrier)? My house is a 24 x 60 modular home including the porch roof.

  10. bo williams, June 16:

    My home is 5100 sq ft. Total. How many squares are on the roof? I was taught to always go 5 squares over the footprint. Is this true?

  11. Sam ellis, June 18:

    How much material will it take to put a roof on a house 2800sq ft

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