Feet and Inches Calculator
Add, subtract, multiply and divide lengths written in ft’in” format — 5'7" + 2'9" = 8'4". Batch-add many measurements, keep a running total tape-measure style, and convert every result to decimal inches, decimal feet and centimeters.
Tip: type 5'7", 5 ft 7 in, 5-7 or 67" — the parser accepts them all.
Tape-measure style: entries stay listed, remove any single one, the grand total updates instantly.
Quick reference table
| Measurement | Inches | Feet | cm |
|---|---|---|---|
| 1" | 1 | 0.0833 | 2.5400 |
| 6" | 6 | 0.5000 | 15.2400 |
| 1' | 12 | 1.0000 | 30.4800 |
| 2'6" | 30 | 2.5000 | 76.2000 |
| 5'7" | 67 | 5.5833 | 170.1800 |
| 6'0" | 72 | 6.0000 | 182.8800 |
| 10' | 120 | 10.0000 | 304.8000 |
| 100" | 100 | 8.3333 | 254.0000 |
How the arithmetic works
Every measurement is converted to total inches first (feet × 12 + inches), the arithmetic happens on that single number, and the result is normalized back to ft'in" with inches rounded to the nearest 1/16", exactly like reading a tape measure.
- Add: 5'7" + 2'9" = 8'4" (100 in = 254.0000 cm)
- Subtract: 5'7" − 2'9" = 2'10" (34 in); 2'9" − 5'7" = -2'10" when the result goes negative
- Multiply: 2'6" × 3 = 7'6" (90 in); 1'6" × 2.5 = 3'9" with a decimal factor
- Divide: 7'6" ÷ 3 = 2'6" (30 in); as a ratio, 7'6" ÷ 2'6" = 3
- Batch: 5'7" + 2'9" + 3'2" = 11'6" (138 in = 350.5200 cm)
- Fractions: 5'7 1/2" = 67.5 in
Conversion uses the exact international definition: 1 ft = 30.48 cm (1 in = 2.54 cm, 1959). Example: 5'7" = 67 in = 170.1800 cm. Fractional display: 1/16" = 0.0625 in = 0.15875 cm.
Looking for something else?
This tool does arithmetic on lengths. If you only need unit conversion or an area, these fit better:
- Feet and Inches to Cm Converter — converts a single ft'in" measurement to centimeters (conversion only, no arithmetic).
- Square Calculator — area from length × width with feet-and-inches input, plus a material estimator.
- Length Converter — converts between inches, feet, yards, miles, mm, cm, meters and km.
- Height Ft Cm — height-focused ft+in ↔ cm converter with a healthy BMI range chart.
- Imperial to Metric Conversion — general imperial/metric conversion tables.
Frequently asked questions
How do I add feet and inches?
Type each measurement in feet-and-inches format, for example 5'7" and 2'9", then choose Add. The calculator converts both to total inches (67 + 33 = 100), adds them, and shows the result as 8'4" — also as 100 inches, 8.3333 feet and 254 cm.
Which input formats are accepted?
The parser accepts 5'7", 5'7, 5 ft 7 in, 5ft7in, 5-7, 67", 67 in, decimal feet like 5.5', and fractions like 7 1/2" or 5'7 1/2". A leading minus sign makes a measurement negative, and the unicode prime marks ′ ″ work too.
How do I subtract feet and inches?
Choose Subtract: 5'7" − 2'9" = 2'10" (67 − 33 = 34 inches). Results can be negative — 2'9" − 5'7" = -2'10" — which is useful for cut lists and remainders.
How do I multiply feet and inches by a number?
Choose Multiply and type a plain number as the second value: 2'6" × 3 = 7'6" (30 × 3 = 90 inches). Decimals work too: 1'6" × 2.5 = 3'9" (45 inches).
How do I divide feet and inches?
Two kinds of division are supported. Measurement ÷ number splits a length: 7'6" ÷ 3 = 2'6" (90 ÷ 3 = 30 inches). Measurement ÷ measurement (Ratio) compares two lengths: 7'6" ÷ 2'6" = 3.
How do I add many measurements at once?
Use the Batch & Running Total tab: paste one measurement per line — for example 5'7", 2'9" and 3'2" — and the tool sums them to 11'6" (138 inches = 350.52 cm).
What is the running total mode?
It works like a tape-measure notebook: every entry you add stays listed, you can remove any single entry, and the grand total updates instantly. Handy for cut lists, room perimeters and material takeoffs.
How many inches are in 8'4"?
8'4" is 100 inches, which is 8.3333 feet. Multiply the feet by 12 and add the inches: 8 × 12 + 4 = 100.
How many centimeters are in one foot?
Exactly 30.48 cm. One inch is defined as exactly 2.54 cm (international definition, 1959), so one foot is 12 × 2.54 = 30.48 cm.
How do I convert feet and inches to cm?
Convert to total inches first, then multiply by 2.54. Example: 5'7" = 67 inches, and 67 × 2.54 = 170.18 cm. The converter tab shows cm, mm, meters and decimal feet for any measurement.
What does the fractional inch display mean?
Results are also shown to the nearest 1/16 of an inch, the way tape measures read: 7.5 inches displays as 7 1/2", and 1/16" equals 0.0625 inches (0.15875 cm).
Can results be negative?
Yes. Subtracting a larger measurement from a smaller one gives a negative result, for example 2'9" − 5'7" = -2'10". Negative inputs are accepted with a leading minus sign, like -2'9".
Is this the same as a feet-and-inches-to-cm converter?
No. A feet-and-inches-to-cm converter only converts one measurement to centimeters. This calculator does arithmetic — add, subtract, multiply and divide in ft'in" format — plus batch addition, a running total, and full unit conversion of every result.
Is this a square footage calculator?
No. A square footage calculator multiplies length × width to get an area. This tool works on single lengths only: it adds, subtracts, multiplies and divides measurements such as 5'7" and 2'9".
Is this feet and inches calculator free, and does my data leave my browser?
Yes, it is free, and everything runs locally in your browser — no measurement you type is sent anywhere.
Free tool by NRTechStudio