Length Converter – cm to Inches, Feet & More

Value

Converted

0.3937007874 in

How the Length Converter Works

Type a number, choose the unit you are starting from, and choose the unit you want. The converted value appears as you type — there is no button to press and no page reload to wait for. Every conversion runs inside your browser using exact conversion factors, so the answer is ready in the same instant you finish typing.

The converter works in both directions. If you have the answer the wrong way round, press the swap key beside the result and the two units exchange places, carrying the converted value with them. Converting 30 centimeters to inches gives 11.81102362 inches; press swap and the tool shows 11.81102362 inches converted back to 30 centimeters. Nothing is lost in the turnaround, so you can flip back and forth while you are working something out.

Results are shown to ten significant digits rather than a fixed number of decimal places. This matters more than it sounds. A single unit family stretches across an enormous range — a nanometer is one billionth of a meter, while a nautical mile is nearly two thousand meters — so any fixed number of decimals would show nothing but zeros at one end of the scale and round away everything useful at the other. Significant digits keep the precision where the precision actually is.

The copy key puts the plain number on your clipboard without the thousands separators used on screen. Separators make a long number readable, but they get in the way when you paste into a spreadsheet cell, a line of code, or a CAD field, so the copied value leaves them out.

Units Supported

The converter covers the metric and imperial systems along with two units that turn up in specialist work:

Metric: nanometers, micrometers, millimeters, centimeters, meters and kilometers.
Imperial and US customary: inches, feet, yards and miles.
Engineering: thou, also called a mil — one thousandth of an inch, used for material thicknesses, tolerances and printed circuit board traces.
Navigation: nautical miles, used in aviation and at sea, and defined as exactly 1,852 meters.

The units are listed metric-first in ascending size, then imperial in ascending size. Interleaving the two systems by magnitude would make the list shorter to read and much harder to search, so they stay grouped the way you think about them.

Where the Numbers Come From

The imperial conversion factors used here are exact by definition, not approximations. The international yard and pound agreement of 1959 defined the inch as exactly 25.4 millimeters, and the foot, yard and mile all follow from that single definition:

1 inch = 25.4 millimeters exactly
1 foot = 12 inches = 0.3048 meters exactly
1 yard = 3 feet = 0.9144 meters exactly
1 mile = 1,760 yards = 1,609.344 meters exactly
1 nautical mile = 1,852 meters exactly

Because these are definitions rather than measurements, a length conversion never goes out of date and never needs to check a server for the current value. That is what makes this kind of tool a good fit for running entirely on your own device.

Common Conversions at a Glance

If you only need one of the handful of conversions people look up most often, here they are:

1 centimeter = 0.3937007874 inches
1 inch = 2.54 centimeters
1 meter = 3.280839895 feet
1 foot = 30.48 centimeters
1 meter = 1.093613298 yards
1 kilometer = 0.6213711922 miles
1 mile = 1.609344 kilometers
1 nautical mile = 1.150779448 miles
1 millimeter = 39.37007874 thou

Use the tool above whenever your number is not exactly one, which is most of the time.

Why Use This Converter

Instant: The result updates on every keystroke. There is no convert button, no loading spinner and no round trip to a server.
Precise: Ten significant digits, using exact definitional factors, with no silent rounding to two decimal places.
Reversible: One key swaps the units and carries the value across, so you can work a problem from either end.
Honest about small numbers: Very large and very small results switch to scientific notation instead of printing a wall of zeros that nobody can count.
Forgiving input: Paste "1,000" or "1 000" and it reads as one thousand. Scientific notation like 1e6 works too.
Works everywhere: The layout is built for phones first, so the number stays readable and the keyboard stays out of the way of the answer.

Your Data Stays on Your Device

Every calculation on this page happens in your browser. The number you type is never transmitted, never logged and never stored. There is no account to create, no analytics tracking what you convert, and no cookies used to follow you between visits.

For a length converter this might seem like a small thing, but the numbers people convert are often more revealing than they look — component dimensions before a patent filing, plot measurements before a property offer, or clinical measurements that belong to a patient. The safest way to handle any of that is not to collect it in the first place, which is exactly what a tool that runs locally does.

It also means the converter works with no connection at all. Once the page has loaded, you can put your device into airplane mode and every conversion still works, because there was never anything on the other end to talk to.

Who This Is For

Engineers and machinists: Move between metric drawings and imperial tooling, or between millimeters and thou when checking tolerances.
Architects and builders: Reconcile plans drawn in meters with materials sold in feet and inches.
Designers and print professionals: Convert artboard dimensions, bleed measurements and stock sizes between millimeters and inches.
Makers, woodworkers and 3D printing hobbyists: Follow a plan written in one system using tools calibrated in the other.
Students and teachers: Check homework answers, or generate worked examples with exact factors rather than textbook approximations.
Runners, cyclists and swimmers: Translate race distances between kilometers and miles, or pool lengths between meters and yards.
Sailors and pilots: Move between nautical miles and the units on a road map or a topographic chart.
Anyone shopping internationally: Work out whether furniture listed in centimeters will fit a space measured in feet.

Examples of Use

Fitting furniture: A sofa listed as 210 cm wide needs to fit an alcove measured at 7 feet. Convert one to the other and find out before it is delivered.
Reading a European plan: A drawing specifies a 2.4 m ceiling. Convert it to feet and inches to compare against a local building code written in imperial.
Ordering materials: A cut list is written in inches but the supplier sells sheet goods in millimeters. Convert each dimension before placing the order.
Checking a tolerance: A spec calls for 5 thou of clearance. Convert to millimeters to check it against a metric feeler gauge.
Planning a run: A 10 kilometer race in miles, or a 5 mile route in kilometers, so you can pace it against what your watch shows.
Preparing artwork: A poster specified at 24 inches wide, converted to millimeters for a printer who works in metric.
Marine navigation: A 15 nautical mile leg converted to kilometers to compare against a coastal map.
Science and lab work: A 500 nanometer wavelength expressed in micrometers or millimeters when scaling a diagram.
Sports fields: A 100 yard football field in meters, or a 50 meter pool in yards when comparing lap counts.
Travel: Road signs in kilometers converted to miles, or a hiking trail listed in miles converted for a metric map.

Tips for Getting the Most From It

Start with one. The page loads with a value of 1 already entered, so you can read the conversion factor between any two units just by picking them.
Use swap to check yourself. Converting back should return your original number. If it does not, the units were the wrong way round.
Paste freely. Numbers copied from a spreadsheet often carry thousands separators. Paste them as they are; the converter reads them correctly.
Watch for scientific notation. A result like 6.213712e-13 means the answer is a very small number, not an error. It appears only when a plain decimal would be unreadable.
Copy the number, not the unit. The copy key gives you the bare value, ready to paste into a calculation.

Length, Distance and Height

Length, distance and height are all the same physical quantity measured along one dimension, so the same converter handles all three. Whether you are describing how long a piece of timber is, how far away a town is, or how tall a doorway is, the underlying unit is the same and the conversion factors do not change. The only difference is which units feel natural: millimeters and inches for objects, meters and feet for rooms and buildings, kilometers and miles for journeys, and nautical miles at sea.