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
| Field | What to enter |
|---|---|
| First length: feet | A number |
| First length: inches | A number |
| Operation | Choose one: Add (+), Subtract (−), Multiply by a number (×), Divide by a number (÷) |
| Second length: feet | A number |
| Second length: inches | A number |
| Number | A number |
| Round to the nearest | Choose 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
Formula
total inches = feet × 12 + inchesresult = A ± B, or A × n, or A ÷ nWorked 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.
Frequently asked questions
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.