# What is the total in feet and inches?

Adds or subtracts two lengths in feet and inches, or multiplies or divides one by a number, and shows the result in feet and inches to the nearest fraction of an inch, in inches, feet and centimetres.

- Page: https://www.acalculator.org/construction/feet-and-inches-calculator
- JSON spec: https://www.acalculator.org/construction/feet-and-inches-calculator.json
- Version: bfd8a94038f4

## Default answer

Example with the default inputs (First length 5 ft 7.5 in, Operation +, Second length 2 ft 8.25 in, Round to 1/16 in): The result is 8 ft 3 3/4 in.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| a | First length | The first length. |
| op | Operation | Add or subtract a second length, or multiply or divide by a number. |
| b | Second length | The length to add or subtract. |
| n | Number | The number to multiply or divide the first length by. |
| den | Round to | The smallest fraction of an inch to show. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| result | Result | The result in feet and inches, to the nearest fraction of an inch chosen. |
| inches | In inches | The exact result in inches. |
| feet | In feet | The exact result in decimal feet. |
| centimeters | In centimetres | The exact result in centimetres. |

## Method

result = first ± second, or first × number, or first ÷ number; shown as feet, whole inches and the nearest fraction of an inch

## Assumptions

- 1 ft = 12 in, and 1 in = 2.54 cm exactly.
- The feet-and-inches result rounds to the nearest fraction chosen; a value exactly halfway rounds up (away from zero). The inch, foot and centimetre results are not rounded.
- A negative result (a longer length subtracted) shows a minus sign in front.
- Zero feet or zero inches are left out of the feet-and-inches result (3 ft, 5/16 in); a result of zero is 0 in.

## Worked examples

1. a = 1.7145, op = add, b = 0.81915, den = 16 gives result = 8 ft 3 3/4 in, inches = 2.53365. Source: hand calculation in content.mdx: 5 ft 7 1/2 in + 2 ft 8 1/4 in = 7 ft 15 3/4 in = 8 ft 3 3/4 in.
2. a = 0.9652, op = subtract, b = 1.222375, den = 16 gives result = −10 1/8 in, inches = -0.257175. Source: hand calculation in content.mdx: 38 in − 48 1/8 in = −10 1/8 in.
3. a = 3.048, op = divide, n = 2, den = 16 gives result = 5 ft, inches = 1.524. Source: hand calculation in content.mdx: 120 in ÷ 2 = 60 in = 5 ft exactly.
4. a = 2.1336, op = divide, n = 3, den = 16 gives result = 2 ft 4 in, feet = 0.7112. Source: hand calculation in content.mdx: 84 in ÷ 3 = 28 in = 2 ft 4 in.
5. a = 0.0254, op = divide, n = 3, den = 16 gives result = 5/16 in. Source: hand calculation in content.mdx: 1/3 in = 5.33/16 in, which rounds to 5/16 in.
6. a = 1.85674, op = multiply, n = 2.5, den = 8 gives result = 15 ft 2 3/4 in, inches = 4.64185. Source: hand calculation in content.mdx: 73.1 in × 2.5 = 182.75 in = 15 ft 2 3/4 in.

## FAQ

### How do I add feet and inches?

Add the feet and the inches separately, then turn every 12 inches into a foot. 5 ft 7 1/2 in + 2 ft 8 1/4 in = 7 ft 15 3/4 in = 8 ft 3 3/4 in.

### How do I subtract feet and inches?

Convert both lengths to inches, subtract, and convert back. 4 ft 1/8 in − 3 ft 2 in is 48 1/8 − 38 = 10 1/8 in. If the second length is longer, the answer is negative.

### How do I divide a length into equal parts?

Choose ÷ and enter how many parts. 7 ft ÷ 3 is 84 in ÷ 3 = 28 in = 2 ft 4 in. When the answer is not a whole fraction of an inch, it rounds to the nearest one you chose.

### How do I convert decimal inches to a fraction?

Multiply the decimal part by the denominator you want and round. 0.33 in × 16 = 5.3, which rounds to 5, so 0.33 in is about 5/16 in.

### Why round to 1/16 of an inch?

Most tape measures in the US are marked in 1/16 in. Choose 1/32 or 1/64 for finer work, or 1/8 or 1/4 for rough framing.

### Can I enter centimetres?

Yes. Pick cm, mm or m in the unit list for either length. The answer is still shown in feet and inches, and in centimetres.

## Sources

- NIST SP 811 (2008), Appendix B: 1 ft = 12 in; 1 in = 2.54 cm exactly.