Feet and inches
The international foot is exactly 0.3048 meters, a third of a yard, and is divided into 12 inches. Height in the US and UK, aircraft altitude worldwide, and room and property sizes in the US are given in feet.
The inch is exactly 25.4 millimeters, one twelfth of a foot. Screen diagonals, wheel and tire sizes, pipe threads, and most US measurements of small objects use inches.
Worked example
Convert 5.5 ft: 5.5 × 12 = 66, so 5.5 feet is 66 inches. Likewise 2 ft = 24 in.
Estimating in your head
The factor is a short exact number, so mental math needs no rounding: multiply by 12.
Going the other way
To convert inches to feet, divide by 12 (or multiply by 0.0833333333333). The swap button between the boxes opens that page.
How this works
in = ft × 12
1 ft = 0.3048 m and 1 in = 0.0254 m, both by definition, so the factor is their ratio: 12 exactly. Results drop binary floating-point noise beyond 15 significant digits and display at the precision you choose (6 significant figures by default). Copy result copies the full value.
Frequently asked
How many inches are in a foot?
1 foot = 12 inches, exactly. The value follows from the unit definitions, so it never changes.
How do I convert feet to inches?
Multiply by 12. For example, 2 ft × 12 = 24 in.
What is 10 ft in inches?
10 ft = 120 in. The table next to the converter lists more common values.
Is the result rounded?
Only on screen. The page computes with the exact definitions and removes floating-point noise past 15 significant digits; pick 3 to 12 significant figures, or use Copy result for the full value.
Sources
- NIST SP 811 Appendix B.8 — Factors for units listed alphabetically
- Federal Register 59-5442 (1959) — Refinement of values for the yard and the pound
- Wikipedia — Conversion of units of length
Reviewed Oct 17, 2026 · test vectors fixtures/units/length/feet-to-inches/