Feet and Inches Calculator: Add Measurements Easily

A feet-and-inches calculator adds lengths written in feet and inches, including measurements with fractional inches, and returns a total in feet and inches. Enter the feet and inches for each measurement; the calculator adds them and carries every 12 inches into 1 foot.

Formula

Convert each measurement to inches, add the inch totals, then divide by 12 to express the result in feet and leftover inches:

Total inches = 12 × (feet₁ + feet₂) + inches₁ + inches₂

Total feet = floor(total inches ÷ 12). Remaining inches = total inches − 12 × total feet.

Here, feet₁ and feet₂ are the whole-foot entries, measured in feet (ft); inches₁ and inches₂ are the additional entries, measured in inches (in). There are exactly 12 inches in one foot. The calculator’s result is formatted as feet plus leftover inches. For instance, a result of 9 ft 2 in is equivalent to 110 in.

Worked Example

Using the default entries, add 5 ft 8 in and 3 ft 4 in:

1. Convert the first measurement to inches: 5 × 12 + 8 = 68 in.
2. Convert the second measurement: 3 × 12 + 4 = 40 in.
3. Add them: 68 + 40 = 108 in.
4. Divide by 12: 108 ÷ 12 = 9 ft, with 0 in remaining.

Total: 9 ft 0 in. This is also 108 in, or 9 ft. The calculator displays two decimal places for the remaining inches when the result has a fractional inch.

When to Use a Feet-and-Inches Calculator

This calculator is useful whenever several lengths need to be combined but are written in the customary feet-and-inches format rather than as a single number. Common examples include adding room dimensions, combining cut lengths, totalling a person’s height measurements, or checking the overall length of adjacent objects. It handles the carrying step automatically, which helps avoid totals such as “8 feet 15 inches” when a conventional feet-and-inches answer is wanted.

For a project with more than two measurements, add them in pairs or first convert every length to inches and sum the inch values. The same method works for any number of lengths. Keep a written record of each entry when measuring multiple parts so that a measurement is not accidentally omitted or entered twice.

How to Enter and Read the Measurements

Enter the whole-foot part in a feet field and the additional inch part in an inches field. For example, enter 6 and 7 for 6 ft 7 in. If a length is less than a foot, use 0 feet and enter the full length in inches. A measurement of 10 inches is therefore 0 ft and 10 in.

If the calculator accepts decimal numbers, fractional inches can be entered as decimals: 3/4 in is 0.75 in, and 1/2 in is 0.5 in. For a mixed fraction such as 2 1/4 in, enter 2.25 in. Keep the feet field and inches field in their stated units; do not enter a complete decimal-foot measurement in an inches field.

After addition, a remainder below 12 inches appears alongside the whole-foot total. A remainder of 12 inches or more should be carried into the feet total. For example, 4 ft 10 in + 2 ft 7 in equals 6 ft 17 in before carrying, or 7 ft 5 in after carrying.

Common Mistakes and Measurement Precision

• Adding feet and inches separately without carrying: If the inch sum is 12 or more, convert each full 12 inches into one foot.
• Confusing decimal feet with inches: 0.5 ft is 6 in, while 0.5 in is half an inch. They are not interchangeable.
• Misreading a fraction: 1/8 in is 0.125 in, not 0.8 in. Convert fractions carefully, especially for small tolerances.
• Rounding too early: Add the original measurements first, then round the final result to the precision the task needs. Early rounding can accumulate error.
• Mixing units: Convert metric measurements before adding them to feet and inches. One inch is exactly 2.54 centimeters; one foot is exactly 0.3048 meters.

The arithmetic can be exact for the numbers entered, but the answer cannot be more reliable than the measurements. A tape measure, ruler, or marked material may have limited precision, and measurements can vary slightly with how they are taken. Record whether a value is measured to the nearest inch, quarter inch, millimeter, or another increment, and avoid implying greater physical accuracy than the measuring method supports.

Conversions and Related Calculations

To convert a feet-and-inches length to inches, multiply the feet by 12 and add the inches. To convert inches to feet as a decimal, divide the total inches by 12. For example, 5 ft 8 in is 68 in, and 68 ÷ 12 is 5.6667 ft (approximately). The decimal form is useful in formulas but can be less intuitive for reading a tape measure.

For metric conversion, multiply inches by 2.54 to get centimeters, or multiply feet by 0.3048 to get meters. Thus 5 ft 8 in equals 68 in, which is 172.72 cm or 1.7272 m. These are unit conversions, not a change in the measured length. For area, volume, or material quantities, length addition alone is not enough: those calculations require additional dimensions and, where relevant, allowances for joints, cuts, or waste.

Frequently Asked Questions

How do I add feet and inches by hand?
Convert each length to inches, add the inch totals, then divide by 12. The quotient is the feet and the remainder is the leftover inches. Alternatively, add feet and inches separately and carry each 12 inches into 1 foot.

How many inches are in a foot?
One foot equals 12 inches. This exact relationship is the basis for adding and converting feet-and-inches measurements.

How do I add measurements with fractions of an inch?
Convert the fractions to decimal inches or a common fraction before adding. For example, 1/2 in is 0.5 in and 1/4 in is 0.25 in, so 2 ft 1/2 in + 1 ft 1/4 in = 3 ft 0.75 in.

What is 5 feet 8 inches in inches?
Multiply 5 feet by 12 to get 60 inches, then add 8 inches. The total is 68 inches.

Can I add feet and inches to centimeters?
Yes, but convert one measurement system first. Convert feet and inches to centimeters using 1 in = 2.54 cm, or convert the metric length to inches, then add values in the same unit.

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in feet1 | First measurement: feet | ft | 5 | 0
in inches1 | First measurement: inches | in | 8 | 0
in feet2 | Second measurement: feet | ft | 3 | 0
in inches2 | Second measurement: inches | in | 4 | 0
out total | Total length | ft and in | floor((feet1*12+inches1+feet2*12+inches2)/12) + " ft " + ((feet1*12+inches1+feet2*12+inches2)-floor((feet1*12+inches1+feet2*12+inches2)/12)*12) + " in" | 2