Length Converter
A length converter changes a measurement from one unit to another by multiplying by a fixed factor. Every unit is defined against the meter: 1 inch = 2.54 cm exactly, 1 foot = 0.3048 m, 1 mile = 1,609.344 m. Example: 100 cm ÷ 2.54 = 39.3701 inches.
Result
not a number
Paste a spreadsheet column, one value per line. Semicolons, tabs and spaces separate values too, and so does a comma — unless it groups thousands inside one number, as in 1,234, which is read as 1234.
Paste or type at least one number to convert.
| # | Input () | Result () |
|---|---|---|
All Conversions
Common Conversions
Reference Table
| From | m | ft | in | km |
|---|---|---|---|---|
Popular Tools
How do you convert length units?
Every conversion is one multiplication and one division. Take the value, multiply by the source unit's size in meters, then divide by the target unit's size in meters. Going from yards to inches: 40 yd × 0.9144 = 36.576 m, then ÷ 0.0254 = 1,440 in. The meter is the pivot, so ten units need ten factors instead of ninety pairs — and no intermediate result is ever rounded before the last step.
What are the exact length conversion factors?
Factors marked exact are fixed by definition, not measured. The rest are those definitions inverted and rounded to six decimals.
| Conversion | Multiply by | Example |
|---|---|---|
| Inches → Centimeters | 2.54(exact) | 10 in = 25.4 cm |
| Centimeters → Inches | 0.393701 | 10 cm = 3.937 in |
| Feet → Meters | 0.3048(exact) | 6 ft = 1.8288 m |
| Meters → Feet | 3.280840 | 2 m = 6.5617 ft |
| Yards → Meters | 0.9144(exact) | 100 yd = 91.44 m |
| Miles → Kilometers | 1.609344(exact) | 5 mi = 8.04672 km |
| Kilometers → Miles | 0.621371 | 10 km = 6.2137 mi |
| Millimeters → Inches | 0.039370 | 25 mm = 0.9843 in |
| Nautical Miles → Kilometers | 1.852(exact) | 12 nmi = 22.224 km |
| Micrometers → Millimeters | 0.001(exact) | 500 µm = 0.5 mm |
How do you convert height in feet and inches to centimeters?
Multiply total inches by 2.54. Forms usually want a whole number of centimeters, so the last column is what you write down.
| Height | Total inches | Centimeters |
|---|---|---|
| 5 ft 0 in | 60 | 152.4 |
| 5 ft 2 in | 62 | 157.5 |
| 5 ft 4 in | 64 | 162.6 |
| 5 ft 6 in | 66 | 167.6 |
| 5 ft 8 in | 68 | 172.7 |
| 5 ft 10 in | 70 | 177.8 |
| 6 ft 0 in | 72 | 182.9 |
| 6 ft 2 in | 74 | 188.0 |
Can you convert a length into square meters or a diameter?
No, and this is the most common misuse of a length converter. Square meters are an area and need two dimensions: 4 m × 3 m = 12 m². A diameter needs a circle: divide a circumference by π (100 mm around gives a 31.83 mm diameter). Convert the units first, then do the geometry — mixing the two steps is where the mistakes come from.
Which units does this length converter support?
Ten units in both directions: micrometer (µm), millimeter (mm), centimeter (cm), meter (m) and kilometer (km) on the metric side; inch (in), foot (ft), yard (yd), mile (mi) and nautical mile (nmi) on the other. The micrometer covers coating thickness and machining tolerances, the nautical mile covers marine and aviation charts. Any of the ten converts to any other, and the all-conversions grid shows all ten at once.
Sources
Definitions and conversion factors on this page follow the official US and international references:
- NIST Special Publication 811 — Guide for the Use of the International System of Units (conversion factors, Appendix B.8)
- NIST Office of Weights and Measures — Unit conversion
- BIPM — The International System of Units (SI Brochure), definition of the meter
- NIST — U.S. Survey Foot: obsolete since 1 January 2023, superseded by the international foot
About Length Converter
Length is the one measurement everybody has to translate. A German furniture page gives depth in centimeters, a US lumber yard sells boards in feet, a machine drawing is dimensioned in millimeters and a sailing chart marks distance in nautical miles. This length converter holds ten units — millimeter, centimeter, meter, kilometer, micrometer, inch, foot, yard, mile and nautical mile — and moves between any two of them through a single pivot: the meter. That pivot is what keeps the numbers honest. Each unit carries one factor in meters, so the tool never chains rounded intermediate results.
Six of those factors are exact by international definition rather than by measurement: an inch is 2.54 centimeters, a foot is 0.3048 meters and a yard is 0.9144 meters, all fixed by the 1959 international yard and pound agreement; a mile is exactly 1,609.344 m and a nautical mile exactly 1,852 m; and a micrometer is exactly 0.001 mm, because the SI prefixes are exact. Everything else you see — 3.280839895 feet in a meter, 0.621371 miles in a kilometer — is a division, and the precision buttons decide how much of it you keep.
Three things separate this page from a static conversion chart. The result updates as you type, so you can feel how a value moves instead of pressing a button per attempt. The all-conversions grid shows one value in all ten units simultaneously, which is the fastest way to sanity-check a figure before it goes into a spec. And the bulk list tab takes a whole column of numbers, pasted straight out of a spreadsheet one per line, converts every row at once, and hands the table back as tab-separated text or a CSV download.
Below the tool you will find the exact multiplication factors, a feet-and-inches to centimeters height table, and answers to the questions that actually trip people up: why a length cannot become square meters, when a length becomes a diameter, and how far a nautical mile really is from a statute one.
Use Cases
How to convert a length step by step
Pick the unit you are converting from: millimeter, centimeter, meter, kilometer, micrometer, inch, foot, yard, mile or nautical mile.
Pick the unit you want, or press the swap button between the two menus to reverse the direction.
Type the value. The result updates as you type — there is no Convert button to press.
Set precision to 2, 4, 6 or 8 decimal places depending on whether you are shopping or machining.
Read the all-conversions grid to see the same value in all ten units at once, and click any card to make it the target unit.
For many values, open the bulk list tab, paste one number per line, then copy the table or export it as CSV.
Pro Tips
- Six factors on this page are exact by definition rather than measured: 1 in = 2.54 cm, 1 ft = 0.3048 m, 1 yd = 0.9144 m, 1 mi = 1.609344 km, 1 nmi = 1.852 km and 1 µm = 0.001 mm. Every factor in the opposite direction is a division of one of them, so rounding early is what breaks a conversion.
- Raise precision to 6 or 8 decimals for small values. At 2 decimals a 0.004 in gap has no decimal digits left, so the tool prints 4.00e-3 instead of a misleading 0; anything below 0.0001 switches to scientific notation as well.
- Swap reverses the two unit menus and keeps the number you typed: 100 cm → in becomes 100 in → cm (254 cm) in one click. It is the fastest way to check a factor in both directions.
- The US survey foot was retired on 31 December 2022. Land and survey records dated after that use the international foot of exactly 0.3048 m — a difference of 2 ppm, or 3.2 mm per mile.
- Paste a spreadsheet column straight into the bulk list, one value per line, then export the result as CSV and paste it back beside the original column.
Frequently Asked Questions
Convert to meters, then out again. Multiply your value by the source unit's factor in meters, then divide by the target unit's factor. Converting 3 miles to kilometers: 3 × 1,609.344 = 4,828.032 m, then ÷ 1,000 = 4.828032 km. Chaining through the meter means you only memorize one number per unit instead of dozens of pairs.
Exactly 2.54 cm. Since the 1959 international yard and pound agreement the inch is defined as 2.54 centimeters, so the figure is a definition rather than a measurement and never rounds. Going the other way, 1 cm = 1 ÷ 2.54 = 0.3937007874 in. That is why 100 cm shows here as 39.3701 in at four decimal places.
Turn the height into inches first, then multiply by 2.54. For 5 ft 9 in: (5 × 12) + 9 = 69 inches, and 69 × 2.54 = 175.26 cm, normally written 175 cm. To go back, divide centimeters by 2.54 for total inches, then divide by 12 — 180 cm is 70.87 in, which is 5 ft 10.9 in.
Divide by 0.3048, or multiply by 3.280839895. Two meters is 2 ÷ 0.3048 = 6.5617 ft. To express that in feet and inches, keep the whole feet and multiply the remainder by 12: 0.5617 × 12 = 6.74, so 2 m is about 6 ft 6.7 in. The factor is exact, so any error comes from your rounding.
No — length and area are different quantities. Square meters need two dimensions: multiply length by width. A room 4 m long and 3 m wide is 12 m². If your sides are in feet, convert each one to meters first, or divide the square feet by 10.7639, because 1 ft² equals 0.09290304 m² exactly.
Only when the length is a circumference. Diameter = circumference ÷ π and radius = diameter ÷ 2. A pipe measuring 100 mm around has a diameter of 100 ÷ 3.14159 = 31.83 mm and a radius of 15.92 mm. Convert the units here first, then apply π — the unit change and the geometry are separate steps.
A statute mile is exactly 1.609344 km, so 5 miles is 8.04672 km. A nautical mile is exactly 1.852 km, about 15% longer, because it was defined as one minute of latitude — which is why ships and aircraft use it. Speed follows the same unit: one knot is one nautical mile per hour, or 1.852 km/h.
The precision buttons set the number of decimal places and 4 is the default. 100 cm is 39.37007874 in, so four decimals give 39.3701. Pick 2 for shopping and DIY, 6 or 8 for machining and lab work. Anything smaller than 0.0001 switches to scientific notation: 500 µm in miles reads 3.1069e-7 rather than 0, and a value too small for the precision you picked switches too, so a real length is never printed as a bare zero.
A Smoot is 5 ft 7 in, or 1.7018 m — the height of MIT student Oliver Smoot, who was laid end over end along the Harvard Bridge over the Charles River between Boston and Cambridge in 1958 to measure it at 364.4 Smoots and one ear. It is a campus joke rather than a standard, so it is not in the unit list, but convert 1.7018 m to any unit here and you have one Smoot.
Yes. Open the bulk list tab, paste one value per line — a column copied from a spreadsheet works directly — choose the source and target units, and every row converts at once. Semicolons, tabs and spaces separate values as well, and so does a comma unless it groups thousands inside one number: 1,234 is read as 1234. The table can be copied as tab-separated text or downloaded as a CSV file holding the original value, its unit and the converted result in separate columns.