Calculating the amount of materials needed for a construction job can be a difficult task, particularly when measurements on remodeling plans are given in feet and inches. In addition, site plans and schematics may use different measurement schemes  feet and inches or decimal feet  and comparison between plans can be difficult. Instead of attempting to add or multiply fractions, you can simply convert each measurement to decimal feet for easy mathematics. For example, 7 feet 6 inches would convert to a decimal measurement of 7.5 feet.
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Determine the number of whole feet  for example, a measurement of 6 feet 3 3/8 inches includes 6 whole feet. The number of whole feet will be given to the left of the decimal point  in the example, this would be 6.00 feet.

Convert fractions of inches to their decimal equivalents. For example, the measurement of 6 feet 3 3/8 inches includes a fraction of an inch  3/8. Divide the numerator by the denominator to find the decimal fraction of an inch  that is, 3 divided by 8 equals 0.375 inches.

Add whole inches and fractions of inches. For example, the measurement of 6 feet 3 3/8 inches includes 3 whole inches, and you have just calculated that 3/8 inches equals 0.375 inches, yielding a total of 3.375 inches.

Convert inches to decimal feet by dividing the number of whole inches by the number of inches in a whole foot  12. For the example, 3.375 divided by 12 equals 0.28 feet.

Add the decimal fraction of a foot to the number of whole feet. In the example, you would add 0.28 feet to 6.00 feet to find that 6 feet 3 3/8 inches equals 6.28 feet.
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