Feet and Inches Calculator – Add and Subtract Fraction and Decimal Inches, Feet, CM, and MM
Add or subtract inches (both decimal and fraction), feet, centimeters and millimeters. Enter equations just like you would write it on paper, eg. 4′ 3 7/8″ + 5cm. Get results in inches (fraction and decimal), feet, centimeters, and millimeters – all measurements are displayed in imperial and metric.
Inches, Feet, Fraction, Centimeters, and Millimeters Results
Imperial Units
0 Inches (fraction)0 Inches
0 Feet
Metric Units
0 Millimeters0 Centimeters
0 Meters
How to Add, Subtract, Multiply, or Divide Feet, Inches, and Metric Length Measurements
Add, subtract, multiply, and divide as many imperial and metric length values as you want, using normal math equations just like you would write.
Enter inch, foot, centimeter, or millimeters, using symbols, abbreviations, or names.
Get final length measurements in feet, inches, inches in fraction, and decimal form, millimeters, and centimeters. Results will be rounded to the nearest inch fraction.
Converting to Decimal Inches
The first thing to do when adding, subtraction, or doing other math with inches, feet, and other measurements is to convert all of the measurements into a common unit of measurement.
Start by converting inch fractions into decimal, then convert feet, centimeters, and millimeters to inches.
To convert inch fractions to decimal by dividing the bottom half of the fraction by the bottom half on a calculator. If there is a whole number, add it to the decimal value after converting. Our inch fraction calculator can also find the decimal value for an inch fraction
For example:
3/8 = 3 ÷ 8 = .375 inches
Convert feet to inches by multiplying the number of feet by 12, since there are 12 inches in a foot. Use our feet to inches conversion calculator to easily convert.
For example:
3 feet = 3 × 12 = 36 inches
Convert centimeters to inches by dividing the number of centimeters by 2.54, as there are 2.54 centimeters in an inch. You can also use our centimeters to inches conversion calculator.
For example:
5 centimeters = 5 ÷ 2.54 = 1.97 inches
Convert millimeters to inches by dividing the number of centimeters by 25.4. You can also use our millimeters to inches conversion calculator.
For example:
50 millimeters = 50 ÷ 25.4 = 1.97 inches
Adding or Subtracting Inches and Feet
With all measurements in an inch decimal form, add or subtract all measurements as you normally would, using a calculator as needed. The final result will be in inch decimal form and will need to be converted to the desired output measurement.
Multiplying or Dividing Inches and Feet
It is also possible to multiply and divide inches, which can be done by multiplying or dividing the decimal value by a number of your choice. For example, if your inch value is 1.25 and you need to multiply by 2, simply multiply using 1.25 × 2 = 2.5.
Adding Common Inch Fractions
| + 1/8″ | + 1/4″ | + 3/8″ | + 1/2″ | + 5/8″ | + 3/4″ | + 7/8″ | + 1″ | |
|---|---|---|---|---|---|---|---|---|
| 1/8″ | 1/4″ | 3/8″ | 1/2″ | 5/8″ | 3/4″ | 7/8″ | 1″ | 1 1/8″ |
| 1/4″ | 3/8″ | 1/2″ | 5/8″ | 3/4″ | 7/8″ | 1″ | 1 1/8″ | 1 1/4″ |
| 3/8″ | 1/2″ | 5/8″ | 3/4″ | 7/8″ | 1″ | 1 1/8″ | 1 1/4″ | 1 3/8″ |
| 1/2″ | 5/8″ | 3/4″ | 7/8″ | 1″ | 1 1/8″ | 1 1/4″ | 1 3/8″ | 1 1/2″ |
| 5/8″ | 3/4″ | 7/8″ | 1″ | 1 1/8″ | 1 1/4″ | 1 3/8″ | 1 1/2″ | 1 5/8″ |
| 3/4″ | 7/8″ | 1″ | 1 1/8″ | 1 1/4″ | 1 3/8″ | 1 1/2″ | 1 5/8″ | 1 3/4″ |
| 7/8″ | 1″ | 1 1/8″ | 1 1/4″ | 1 3/8″ | 1 1/2″ | 1 5/8″ | 1 3/4″ | 1 7/8″ |
| 1″ | 1 1/8″ | 1 1/4″ | 1 3/8″ | 1 1/2″ | 1 5/8″ | 1 3/4″ | 1 7/8″ | 2″ |
Subtracting Common Inch Fractions
| − 1/8″ | − 1/4″ | − 3/8″ | − 1/2″ | − 5/8″ | − 3/4″ | − 7/8″ | − 1″ | |
|---|---|---|---|---|---|---|---|---|
| 1/8″ | 0″ | -1/8″ | -1/4″ | -3/8″ | -1/2″ | -5/8″ | -3/4″ | -7/8″ |
| 1/4″ | 1/8″ | 0″ | -1/8″ | -1/4″ | -3/8″ | -1/2″ | -5/8″ | -3/4″ |
| 3/8″ | 1/4″ | 1/8″ | 0″ | -1/8″ | -1/4″ | -3/8″ | -1/2″ | -5/8″ |
| 1/2″ | 3/8″ | 1/4″ | 1/8″ | 0″ | -1/8″ | -1/4″ | -3/8″ | -1/2″ |
| 5/8″ | 1/2″ | 3/8″ | 1/4″ | 1/8″ | 0″ | -1/8″ | -1/4″ | -3/8″ |
| 3/4″ | 5/8″ | 1/2″ | 3/8″ | 1/4″ | 1/8″ | 0″ | -1/8″ | -1/4″ |
| 7/8″ | 3/4″ | 5/8″ | 1/2″ | 3/8″ | 1/4″ | 1/8″ | 0″ | -1/8″ |
| 1″ | 7/8″ | 3/4″ | 5/8″ | 1/2″ | 3/8″ | 1/4″ | 1/8″ | 0″ |
Multiplying Common Inch Fractions
| × 2 | × 3 | × 4 | × 5 | × 6 | × 7 | × 8 | |
|---|---|---|---|---|---|---|---|
| 1/8″ | 1/4″ | 3/8″ | 1/2″ | 5/8″ | 3/4″ | 7/8″ | 1″ |
| 1/4″ | 1/2″ | 3/4″ | 1″ | 1 1/4″ | 1 1/2″ | 1 3/4″ | 2″ |
| 3/8″ | 3/4″ | 1 1/8″ | 1 1/2″ | 1 7/8″ | 2 1/4″ | 2 5/8″ | 3″ |
| 1/2″ | 1″ | 1 1/2″ | 2″ | 2 1/2″ | 3″ | 3 1/2″ | 4″ |
| 5/8″ | 1 1/4″ | 1 7/8″ | 2 1/2″ | 3 1/8″ | 3 3/4″ | 4 3/8″ | 5″ |
| 3/4″ | 1 1/2″ | 2 1/4″ | 3″ | 3 3/4″ | 4 1/2″ | 5 1/4″ | 6″ |
| 7/8″ | 1 3/4″ | 2 5/8″ | 3 1/2″ | 4 3/8″ | 5 1/4″ | 6 1/8″ | 7″ |
| 1″ | 2″ | 3″ | 4″ | 5″ | 6″ | 7″ | 8″ |
Dividing Common Inch Fractions
| ÷ 2 | ÷ 3 | ÷ 4 | ÷ 5 | ÷ 6 | ÷ 7 | ÷ 8 | |
|---|---|---|---|---|---|---|---|
| 1/4″ | 1/8″ | 5/64″ | 1/16″ | 3/64″ | 1/32″ | 1/32″ | 1/64″ |
| 1/2″ | 1/4″ | 11/64″ | 1/8″ | 7/64″ | 5/64″ | 1/16″ | 1/16″ |
| 3/4″ | 3/8″ | 1/4″ | 3/16″ | 5/32″ | 1/8″ | 7/64″ | 3/32″ |
| 1″ | 1/2″ | 21/64″ | 1/4″ | 13/64″ | 11/64″ | 9/64″ | 1/8″ |
Inch Fraction and Decimal Equivalents
