Length Converter
Convert between inches, feet, yards, miles, millimeters, centimeters, meters, kilometers and nautical miles — all at once, with exact factors and a reference table.
Length Converter: with the default inputs, meters is 0.3048 m.
- Centimeters
- 30.48 cm
- Millimeters
- 304.8 mm
- Kilometers
- 0.000305 km
- Inches
- 12 in
- Feet
- 1 ft
- Yards
- 0.333333 yd
- Miles
- 0.000189 mi
- Nautical miles
- 0.000165 nmi
Assumptions
- International (1959) definitions: 1 in = 2.54 cm exactly; the US survey foot is not used.
| From | Equals |
|---|---|
| 1 inch | 2.54 cm (exactly) |
| 1 foot | 12 in = 30.48 cm = 0.3048 m |
| 1 yard | 3 ft = 0.9144 m |
| 1 mile | 5,280 ft = 1,760 yd = 1.609344 km |
| 1 nautical mile | 1,852 m = 1.1508 mi |
| 1 millimeter | 0.03937 in |
| 1 centimeter | 0.3937 in |
| 1 meter | 39.37 in = 3.2808 ft = 1.0936 yd |
| 1 kilometer | 0.62137 mi = 3,280.84 ft |
| Feet & inches | cm |
|---|---|
| 5′ 0″ | 152.4 |
| 5′ 1″ | 154.9 |
| 5′ 2″ | 157.5 |
| 5′ 3″ | 160 |
| 5′ 4″ | 162.6 |
| 5′ 5″ | 165.1 |
| 5′ 6″ | 167.6 |
| 5′ 7″ | 170.2 |
| 5′ 8″ | 172.7 |
| 5′ 9″ | 175.3 |
| 5′ 10″ | 177.8 |
| 5′ 11″ | 180.3 |
| 6′ 0″ | 182.9 |
How this is worked out
The formula
1 in = 2.54 cm (exact, by definition since 1959) 1 ft = 12 in = 0.3048 m 1 yd = 3 ft = 0.9144 m 1 mi = 5,280 ft = 1,609.344 m 1 nmi = 1,852 m value in unit B = value in meters ÷ (meters per unit B)
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Length
- A number.in ft · defaults to 1
What you get back
- Metersmain answer
- Centimeters
- Millimeters
- Kilometers
- Inches
- Feet
- Yards
- Miles
- Nautical miles
What this assumes
- International (1959) definitions: 1 in = 2.54 cm exactly; the US survey foot is not used.
About this calculator
Enter a length in any unit and every other unit updates at once. The conversions use the exact legal definitions: since the 1959 international yard and pound agreement, one inch is exactly 2.54 centimeters, which fixes the foot at 0.3048 m and the mile at 1,609.344 m. There's no rounding until the display.
The units
Metric (SI) — the millimeter, centimeter, meter and kilometer differ by powers of ten. The meter is defined by the speed of light: the distance light travels in 1/299,792,458 of a second.
US customary / imperial — 12 inches to a foot, 3 feet to a yard, 1,760 yards (5,280 feet) to a mile. The US and UK use identical definitions for these units today; the only survivor of the old difference is the US survey foot (1200/3937 m), which was retired for new work in 2023.
Nautical mile — 1,852 m exactly, originally one minute of latitude. It's used at sea and in aviation, and the knot is one nautical mile per hour.
Quick mental conversions
- Inches to cm: multiply by 2.5 (2.54 exactly). 6 in ≈ 15 cm.
- Feet to meters: multiply by 0.3, or divide by 3.3. 10 ft ≈ 3 m.
- Miles to km: multiply by 1.6, or use the Fibonacci trick — 5 mi ≈ 8 km, 8 mi ≈ 13 km.
- Km to miles: multiply by 0.6. A 10K run is 6.2 miles.
- Meters to feet: multiply by 3.3. A 3 m ceiling is about 10 ft.
Heights
Height in feet and inches converts as total inches × 2.54. Five foot ten is 70 in = 177.8 cm; six foot is 72 in = 182.88 cm. The table below lists 5′0″ to 6′0″.
Precision
Results are shown to six decimal places with trailing zeros dropped. Because the factors are exact, converting back and forth loses nothing beyond floating-point noise in the 15th digit.
Frequently asked questions
▸How many centimeters are in an inch?
Exactly 2.54 cm. The inch has been defined as 25.4 mm since 1959. To convert inches to cm multiply by 2.54; to convert cm to inches divide by 2.54 (or multiply by 0.3937).
▸How many feet are in a mile?
5,280 feet, or 1,760 yards. A mile is 1.609344 km.
▸How many feet are in a meter?
3.28084 feet (39.37 inches). One foot is 0.3048 m exactly.
▸How do I convert km to miles?
Multiply by 0.621371, or divide by 1.609344. 100 km is 62.1 miles; a marathon's 42.195 km is 26.2 miles.
▸What is the difference between a mile and a nautical mile?
A nautical mile is 1,852 m — about 15% longer than the 1,609 m statute mile — because it was defined as one minute of latitude on the Earth's surface.
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