Feet and Inches Calculator

The feet and inches calculator is your go-to tool for performing arithmetic on imperial length measurements. It handles all four operations — addition, subtraction, multiplication, and division — on values entered in feet and inches, including fractions. No more converting everything to decimals just to do simple math. Enter your measurements, choose your operation, and get an instant result.

What Is a Feet and Inches Calculation?

A feet and inches calculation is arithmetic performed on imperial length measurements that use both feet and inches as units. Since 1 foot equals 12 inches, you can't just add or subtract the numbers directly — you need to account for the unit relationship. For example, adding 5 ft 10 in and 1 ft 5 in doesn't give you 6 ft 15 in. You carry over the extra inches into feet, giving you 7 ft 3 in. This calculator handles all that conversion automatically.

The Feet and Inches Conversion Formulas

These three formulas are the backbone of any feet and inches calculation:

Inches to Feet

Inches ÷ 12 = Feet

For example, 36 inches ÷ 12 = 3 feet.

Feet to Inches

Feet × 12 = Inches

For example, 4 feet × 12 = 48 inches.

Mixed Units to Total Inches

(Feet × 12) + Inches = Total Inches

For example, 5 ft 4 in = (5 × 12) + 4 = 64 inches.

These conversions happen behind the scenes every time you use the calculator.

How the Feet and Inches Calculator Works

Inputs

The calculator has two rows of inputs — each with a Feet field and an Inches field. Both default to 0. Between the two rows sits an Operator dropdown where you select +, −, ×, or ÷. The default operator is addition (+).

The Inches field accepts fractions and mixed numbers. You can enter values like:

• Pure fractions: 1/4, 5/8, 78/64

• Mixed numbers: 1+1/2, 5+3/8, 4+5/16

Outputs

The Result section shows your answer in feet and inches. A Precision dropdown (default: 1/2) lets you control how finely fractional inches are expressed. The result also displays the fraction form of the inches — for example, 0 = 0/2" = 0" at the default zero-input state.

How to Calculate Feet and Inches — Step by Step

Example 1: Adding Two Measurements

You have two boards — one that's 3 ft 7 in and another that's 2 ft 8 in. What's the total length?

Step 1: Add the inches — 7 + 8 = 15 inches. Step 2: Convert 15 inches — 15 ÷ 12 = 1 ft with 3 in remaining. Step 3: Add the feet — 3 + 2 + 1 = 6 ft. Step 4: Final answer — 6 ft 3 in.

Using the calculator: Enter 3 in the first Feet field, 7 in the first Inches field. Enter 2 in the second Feet field, 8 in the second Inches field. Set the operator to +. Result: 6 ft 3 in.

Example 2: Subtracting Measurements with Fractions

You have a 10 ft 0 in rod and you cut off 3 ft 5+1/2 in. How much is left?

Step 1: Convert everything to inches.

• 10 ft 0 in = 120 inches

• 3 ft 5+1/2 in = (3 × 12) + 5.5 = 41.5 inches

Step 2: Subtract — 120 − 41.5 = 78.5 inches. Step 3: Convert back — 78.5 ÷ 12 = 6 ft with 6.5 in remaining = 6 ft 6+1/2 in.

Using the calculator: Enter 10 and 0 in the first row. Enter 3 and 5+1/2 in the second row. Set the operator to −. Result: 6 ft 6+1/2 in.

Feet and Inches Reference Table

This table shows common inch values and their equivalent in feet and inches — handy for quick reference.

Note: All values are exact conversions based on 1 foot = 12 inches.

Frequently Asked Questions

What is 5 feet 9 inches in feet?

5 feet 9 inches equals 5.75 feet. You get this by converting 9 inches to feet: 9 ÷ 12 = 0.75. Add that to 5, and you get 5.75 feet. You can also express this as 5+3/4 feet.

How many inches are in a foot?

There are exactly 12 inches in 1 foot. This is the standard imperial conversion used worldwide. So 2 feet = 24 inches, 3 feet = 36 inches, and so on.

Can this calculator handle fractions in inches?

Yes. The calculator accepts both pure fractions (like 1/4 or 5/8) and mixed numbers (like 1+1/2 or 4+5/16) in the Inches field. The Precision setting in the result controls how finely fractional inches are displayed.

What operations does the feet and inches calculator support?

The calculator supports all four basic arithmetic operations — addition (+), subtraction (−), multiplication (×), and division (÷). You select the operation from the Operator dropdown between the two input rows.