# Feet and Inches Calculator

URL: https://speedycalculator.com/calculators/conversion/feet-and-inches-calculator/
Last updated: 2026-10-25

> The feet and inches calculator adds and subtracts lengths written as feet and inches, or multiplies and divides them by a number, and gives the answer in feet, inches and fractions of an inch to the precision you choose.

## Inputs

- First length: feet
- First length: inches
- Operation
- Second length: feet
- Second length: inches
- Number
- Round to the nearest

## Results

- Result
- In inches
- In decimal feet
- In metres

## Formula

```
total inches = feet × 12 + inches
result = A ± B, or A × n, or A ÷ n
```

## Explanation

Carpenters, tailors and DIYers often need to add measurements like 5′ 7 3/8″ + 2′ 9 5/8″. Converting everything to inches first avoids carrying mistakes; the result is turned back into feet and inches and rounded to the nearest fraction.

### How to use the Feet and Inches Calculator

- **First length: feet**
- **First length: inches**
- **Operation**
- **Second length: feet**
- **Second length: inches**
- **Number**
- **Round to the nearest**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Both measurements are converted to inches, combined using the operation you choose, rounded to the selected fraction and split into whole feet and remaining inches.

### Inputs explained

FieldWhat to enterFirst length: feetA numberFirst length: inchesA numberOperationChoose one: Add (+), Subtract (−), Multiply by a number (×), Divide by a number (÷)Second length: feetA numberSecond length: inchesA numberNumberA numberRound to the nearestChoose one: 1/2″, 1/4″, 1/8″, 1/16″ …

### What each result means

- **Result** = round([Total inches (exact)] × [Round to the nearest]) ÷ [Round to the nearest]
- **In inches** = round([Total inches (exact)] × [Round to the nearest]) ÷ [Round to the nearest]
- **In decimal feet** = [Total inches (exact)] ÷ 12
- **In metres** = [Total inches (exact)] × 0.0254

## Worked example

Inputs — First length: feet: 5; First length: inches: 7.375; Operation: Add (+); Second length: feet: 2; Second length: inches: 9.625; Number: 2; Round to the nearest: 1/16″.

Results — **Result = 8 ft 5 in**; In inches = 101; In decimal feet = 8.4167 ft; In metres = 2.5654 m.

## FAQ

**What is 5′ 7 3/8″ + 2′ 9 5/8″?**
8′ 5″.

**How many inches in 3 feet 4 inches?**
40 in.

**Why round to 1/16″?**
Most tape measures are marked in sixteenths of an inch.

**What formula does the Feet and Inches Calculator use?**
total inches = feet × 12 + inches.


## Sources

- [NIST Special Publication 811 – Guide for the Use of the International System of Units](https://www.nist.gov/pml/special-publication-811)
- [NIST Handbook 44 Appendix C – General tables of units of measurement](https://www.nist.gov/pml/owm/nist-handbook-44-current-edition)