How to Convert Feet in Decimal Format to Foot, Inch and Fraction Values
To convert a number in decimal feet format to foot inch and fraction first take out the foot value, the amount before the dot. To take out the number of inches multiply the leftover decimal amount by 12.
The amount before the dot becomes the inch value. What is leftover is the fraction value of one inch.
If you were to convert this to a fraction you could end up something that isn't very useful in construction, like 2364/3365. You have to decide what the denominator of your fraction is going to be.
To be usable 16 would be a good choice for a denominator and still maintain a fair level of accuracy.
Multiply the leftover decimal by 16 and round this number to the nearest whole number. This amount is the numerator of your fraction.
Example: 18.649' in decimal feet. The 18 becomes the foot value, subtract this from the decimal amount 18.649 - 18 = 0.649" 0.649 is the inch value. Take out the whole inches by multiplying this amount by 12. 0.649 * 12 = 7.788. The 7 before the dot is the whole inch value. Remove this 7 from the decimal. 7.788 - 7 = 0.788. The decimal value 0.788 is the fraction of an inch.The exact fraction of 788/10000 is not of much use in construction.
If you decided to use 16 as the denominator for the fraction then multiply the leftover decimal by 16.
0.788 * 16 = 12.608. Round the decimal part to the nearest whole number. In this case, you would round it upward and the amount becomes 13. This 13 is the numerator value of your fraction.
Collect all the numbers:
18.649' in decimal feet becomes 18' 7 13/16"
If you had decided to make the denominator a 2
0.788 * 2 = 1.576 rounded to the nearest whole number 2
Now your result would look like 18' 7 2/2" --- 18' 8" Using a smaller denominator here produced a less accurate result. This will not always be the case but most times you are better off using a larger amount for a denominator.
Now let's check this 18' 7 13/16" result for accuracy by converting it back to decimal format.
You know that the 18, the foot value, belongs before the dot. For starters you will have 18.000. Take the full inch value of 7 and divide this by 12. 7 / 12 = 0.58333333 and then some more three's. Add this to the 18.000.
18.000 + 0.58333333= 18.5833 rounded to 4 digits.
Take the fraction and divide the numerator by the denominator.
13 / 16 = 0.8125. Divide this amount by 10.
0.8125 / 10 = 0.08125. Add this to the previous amount of 18.583.
18.5833 + 0.08125 = 18.665 rounded to three digits.
18.665 - 18.649 = 0.016.
That is an 16/1000 inch difference. I don"t think you have much to worry about with a difference like that when you are building your home!
Or you let this calculator do it for you!
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