How to Measure for Metal Roofing

This roof must be measured on each side of the gable for accuracy.
This roof must be measured on each side of the gable for accuracy. (Image: roof image by Christopher Meder from

When measuring and estimating metal roofing, it is necessary to get your figures right, as failure to do so could be costly. The construction industry has developed, over time, a reasonable approach to measuring and estimating metal roofing that the average do-it-yourselfer can master in one to three hours, depending on experience. By following these tried-and-true methods, you will save thousands in wasted materials and time.

Things You'll Need

  • Tape measure
  • Calculator

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Measure the length and the width of all flat surfaces of the roof. To do this, determine which surface will receive metal. Generally, all roofing surfaces that are exposed to rain should be covered with metal. Measure the length and width of all surfaces, allowing 1 inch extra for overhangs.

Record the measurements on a writing pad, separating the measurements under columns. This will allow you to reference each section or make changes as necessary.

Multiply the length and the width of each section to get the square footage of the section. For example, if you have a section that is 10 feet by 10 feet, multiply the two together and you have 100 square feet. Repeat this on all sections and add the numbers together. This will be your total square footage to be covered by metal.

Divide the total square footage by 100. Because metal roofing is measured in squares, and 10-by-10 feet is one square or 100 square feet, then dividing the total number of square feet will give you the total number of measured squares needed to cover the roof in metal.


  • "Roofing Construction & Estimating"; Daniel Benn Atcheson; 1995
  • "Black & Decker The Complete Guide to Roofing Siding & Trim"; Chris Marshall; 2008
  • "Miller's Guide to Framing & Roofing"; Mark R. Miller; 2005
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