Length Converter
Exact length conversions with feet and inches, inch fractions and every unit at once.
Type a length in plain words — “5 ft 7 in to cm”, “12 inch in mm”, “3.5 km to mi” — or use the boxes below.
Rounded · ft = m ÷ 0.3048
- Metre: SI base unit: the distance light travels in vacuum in 1/299,792,458 of a second
- Foot: exactly 0.3048 m = 12 inches (international foot)
Feet and inches
Enter a height or measurement as feet plus inches. It goes into the converter above (as inches) and is converted to the To unit.
1 m in every unit
Select a unit to convert to it. Values marked ≈ are rounded; all others are exact.
| Unit | Value | Copy |
|---|---|---|
| Metric | ||
| 10,00,00,00,000 | ||
| 1,00,00,00,000 | ||
| 10,00,000 | ||
| 1,000 | ||
| 100 | ||
| from | 1 | |
| 0.001 | ||
| Imperial & US | ||
| ≈ 39,370.07874 | ||
| ≈ 39.37007874 | ||
| ≈ 9.842519685 | ||
| to | ≈ 3.280839895 | |
| ≈ 1.093613298 | ||
| ≈ 0.0006213711922 | ||
| Surveying | ||
| ≈ 4.970969538 | ||
| ≈ 0.1988387815 | ||
| ≈ 0.04970969538 | ||
| ≈ 0.004970969538 | ||
| ≈ 0.0002071237307 | ||
| Nautical | ||
| ≈ 0.5468066492 | ||
| ≈ 0.0005399568035 | ||
| Astronomical | ||
| ≈ 6.684587122 × 10⁻¹² | ||
| ≈ 1.057000834 × 10⁻¹⁶ | ||
| ≈ 3.240779289 × 10⁻¹⁷ | ||
| Legacy | ||
| ≈ 3.280833333 | ||
Convert a list of values
Up to 1,000 lines. Fractions (3/4), mixed numbers (1 1/2) and grouped digits (1,250) are fine.
| Value | Result |
|---|
About the Length Converter
Convert any length between metric, imperial and US units, surveying chains and rods, nautical miles and astronomical units — from ångströms and micrometres to miles, light-years and parsecs. Type in either box and the other updates; every other unit is listed in the table underneath, with the formula used.
The arithmetic is exact. Each unit is stored as its legal definition — an inch is exactly 2.54 cm, a foot 0.3048 m, a chain 66 ft, an astronomical unit 149,597,870,700 m — and calculated with fractions instead of floating-point numbers, so 0.1 ft is exactly 0.03048 m, not 0.030480000000000004. Only the parsec is defined through π; its results are rounded and marked ≈.
For heights, rooms and woodwork, every result is also shown in feet and inches and to the nearest 1/2 to 1/64 inch, and you can type 5 ft 7 in directly.
How to use it
- Type a number in From and pick its unit, then pick the unit you want in To. You can also type in the To box to convert the other way.
- Or type a whole conversion in Quick convert —
5 ft 7 in to cm,12 inch in mm,3.5 km to mi— and press Enter. - For a height or measurement in feet and inches, fill in Feet and inches (for example 5 and 7). Choose how finely inches are rounded; 1/16 inch is the default.
- Read the exact formula under the result, copy it or share a link, and download the table of every unit as CSV. Convert a list converts a whole column of numbers at once.
Examples
5 ft 7 in to cm
170.18 cm (exact)
5 × 12 + 7 = 67 inches, and 67 × 2.54 = 170.18.
1 m to ft
≈ 3.280839895 ft ≈ 3 ft 3.37 in ≈ 3 ft 3 3/8 in (nearest 1/16 in)
1 mi to km
1.609344 km exactly (5,280 ft × 0.3048 m)
1 nmi to ft
≈ 6,076.115486 ft (1,852 m ÷ 0.3048 m)
1 ly to km
9,460,730,472,580.8 km exactly (299,792,458 m/s × 365.25 days)
1 chain to m
20.1168 m (66 ft; 80 chains make a mile)
Common uses
- Converting heights between centimetres and feet-and-inches for forms, IDs and sports profiles.
- Reading drawings and product sizes in mm, inches or fractions of an inch (1/16, 1/32).
- Distances for travel, running and maps in km, miles and nautical miles.
- Old land records and surveys measured in chains, links, rods and furlongs.
- Science homework with nanometres, ångströms, astronomical units, light-years and parsecs.
Where the conversion factors come from
Customary units use the exact relations in NIST Handbook 44 (2026), Appendix C; metric units and the ångström follow the BIPM SI Brochure (9th edition, Table 8).
- Inch = 2.54 cm exactly (1959), so foot = 0.3048 m, yard = 0.9144 m and mile = 1,609.344 m.
- Nautical mile = 1,852 m exactly; the fathom is 6 ft.
- Mil (thou) = 0.001 in = 25.4 µm; the hand, used for horse heights, is 4 in (Handbook 44 puts it in brackets: not in general US use, or based on custom and usage).
- Astronomical unit = 149,597,870,700 m exactly (IAU 2012 Resolution B2).
- Light-year = the distance light travels in a Julian year of 365.25 days: 299,792,458 m/s × 31,557,600 s = 9,460,730,472,580,800 m (the basis given in NIST SP 811, Appendix B.8).
- Parsec = 648,000/π au exactly (IAU 2015 Resolution B2) ≈ 3.0857 × 10¹⁶ m ≈ 3.26 light-years.
Chains, rods, furlongs and the US survey foot
The surveying units are built on Gunter’s chain: 1 chain = 66 ft = 4 rods = 100 links; 10 chains = 1 furlong (660 ft), 80 chains = 1 mile, and 10 square chains make an acre. A rod (also called a pole or perch) is 16½ ft and a league is 3 miles.
Until 2022 the United States defined these units with the US survey foot of 1200/3937 m, which is 2 parts per million longer than the international foot of 0.3048 m — about 3 mm in a mile. The survey foot is deprecated except for historic and legacy data (Federal Register 85 FR 62698), so this converter uses the international foot for every surveying unit. The US survey foot itself is listed under Legacy for converting older US land records.
Feet, inches and fractions of an inch
Lengths up to 10 km are also shown in feet and inches. The decimal line rounds the inches to two places and marks the rounding with ≈ (1 m ≈ 3 ft 3.37 in); the fraction line rounds to the nearest 1/2, 1/4, 1/8, 1/16, 1/32 or 1/64 inch — the marks on a tape measure — and says how far that mark is from the exact length, in inches and millimetres.
Rounding never produces “12 inches”: 5 ft 11.999 in becomes 6 ft 0 in. Fractions are reduced, so 8/16 is shown as 1/2.
Limitations
- Conversions to or from parsecs are rounded (shown with ≈) because the parsec is defined through π.
- Feet-and-inches lines are shown for lengths up to 10 km; they are left out for lengths too short to show in inches (they would round to 0 in).
- Traditional regional units whose length varied from place to place are not included.
- Inputs are limited to 60 characters; very large or very small results are shown in scientific notation.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
How many centimetres are in an inch?
Exactly 2.54. The inch has been defined as 2.54 cm since 1959, so 12 inches (1 foot) are exactly 30.48 cm and 1 cm is about 0.3937 inch.
How do I convert 5 feet 7 inches to centimetres?
Turn it into inches first — 5 × 12 + 7 = 67 inches — and multiply by 2.54: 67 × 2.54 = 170.18 cm. Type 5 ft 7 in to cm in Quick convert, or enter 5 and 7 under Feet and inches.
Is a nautical mile the same as a mile?
No. A nautical mile is exactly 1,852 m and is used at sea and in aviation; a (statute) mile is 1,609.344 m. One nautical mile is about 1.151 miles.
What is the difference between a foot and a US survey foot?
The foot is 0.3048 m exactly. The US survey foot, 1200/3937 m, is 2 parts per million longer and was used for US land surveys until it was deprecated on 1 January 2023. Use it only for older US records; everywhere else, “foot” means 0.3048 m.
Why is a light-year exact here but a parsec is not?
A light-year is defined from the exact speed of light and a Julian year of 365.25 days, so it is a whole number of metres: 9,460,730,472,580,800 m. A parsec is 648,000/π astronomical units, and π never ends, so parsec conversions are rounded and marked ≈.
Can I type fractions such as 3/4 inch or 1 1/2 feet?
Yes. The boxes accept fractions (3/4), mixed numbers (1 1/2), fraction characters (7½), scientific notation (1.5e3) and digit grouping (1,250.5 or 1,00,000). Quick convert also reads 5'7", 5 ft 7½ in and 5 feet 7 1/2 inches.