Add, subtract, multiply, divide, and convert construction fractions used in tape-measure measurements.
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Add two tape-measure fractions.
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Tape measures commonly divide each inch into halves, quarters, eighths, and sixteenths. To add or subtract measurements, the fractions first need a common denominator. Skoppe Calculator handles the fraction math automatically and returns the result in simplified construction-friendly inches, with a decimal and a feet + inches equivalent when the total passes one foot.
Addition: a/b + c/d = (ad + bc) / bd
Subtraction: a/b − c/d = (ad − bc) / bd
Multiplication: a/b × n = an / b
Division: a/b ÷ n = a / (bn)
Simplify the final fraction using the greatest common divisor. The calculator works in exact fractions, so 7 3/8 + 5 11/16 is added as 118/16 + 91/16 rather than as rounded decimals.
Adding 7 3/8 in and 5 11/16 in:
3/8 = 6/16
Both fractions in sixteenths7 6/16 + 5 11/16 = 12 17/16
17/16 = 1 1/16
13 1/16 in13 1/16 in = 13.0625 in
1 ft 1 1/16 inEvery sixteenth of an inch with its decimal and millimeter equivalent. 1 in = 25.4 mm.
| Fraction | Decimal | Millimeters |
|---|---|---|
| 1/16 | 0.0625 | 1.5875 |
| 1/8 | 0.125 | 3.175 |
| 3/16 | 0.1875 | 4.7625 |
| 1/4 | 0.25 | 6.35 |
| 5/16 | 0.3125 | 7.9375 |
| 3/8 | 0.375 | 9.525 |
| 7/16 | 0.4375 | 11.1125 |
| 1/2 | 0.5 | 12.7 |
| 9/16 | 0.5625 | 14.2875 |
| 5/8 | 0.625 | 15.875 |
| 11/16 | 0.6875 | 17.4625 |
| 3/4 | 0.75 | 19.05 |
| 13/16 | 0.8125 | 20.6375 |
| 7/8 | 0.875 | 22.225 |
| 15/16 | 0.9375 | 23.8125 |
| 1 | 1 | 25.4 |
Divide measurements by 2.
Add or subtract fractional dimensions.
Calculate repeated fractional measurements.
Work with tape-measure dimensions without decimal conversion.
Handle precise fractional cuts and offsets.
Convert fractions to decimals or millimeters when needed.
The longest mark between two inch numbers is the half-inch: 1/2.
The next longest marks are the quarters: 1/4 and 3/4.
The shorter marks divide the inch into eighths: 1/8, 3/8, 5/8, and 7/8.
The shortest marks divide the inch into sixteenths. Count the sixteenth marks from the previous whole inch, then simplify — 12/16 reads as 3/4.
Use the Fraction Calculator when you are working primarily with inch fractions or tape-measure math — for example, 7 3/8 in + 5 11/16 in. Results stay inch-first, with a feet + inches equivalent only when the total passes 12 in.
Use the Feet + Inches Calculator when you are working with full construction dimensions containing feet, inches, and fractions — for example, 12 ft 7 3/8 in − 4 ft 9 5/16 in.
Open the Feet + Inches Calculator →| Fraction | Decimal |
|---|---|
| 1/2 | 0.5 |
| 1/4 | 0.25 |
| 3/4 | 0.75 |
| 1/8 | 0.125 |
| 3/8 | 0.375 |
| 5/8 | 0.625 |
| 7/8 | 0.875 |
| 1/16 | 0.0625 |
| 3/16 | 0.1875 |
| 5/16 | 0.3125 |
| 7/16 | 0.4375 |
| 9/16 | 0.5625 |
| 11/16 | 0.6875 |
| 13/16 | 0.8125 |
| 15/16 | 0.9375 |
Convert the fractions to a common denominator, add the numerators, then simplify the result.
Convert both fractions to a common denominator, subtract the numerators, then simplify. If necessary, borrow one whole inch before subtracting.
Divide the measurement by two. For example, half of 11 1/2 inches is 5 3/4 inches.
7/16 equals 0.4375.
0.4375 inch equals 7/16 inch.
There are 16 sixteenths in one inch.
Yes. Fraction results are reduced to their simplest construction-friendly form.
The Fraction Calculator is optimized for inch fractions and tape-measure math. The Feet + Inches Calculator is designed for complete dimensions containing feet, inches, and fractions.
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