Length Converter

Convert any length unit

Whether you are working in metric or imperial, this length converter handles the math for you. It supports kilometers, meters, centimeters, millimeters, micrometers and nanometers on the metric side, plus miles, yards, feet, inches and nautical miles for imperial and marine use.

All conversions are exact, based on the international definition of the meter (1 inch = 2.54 cm, 1 mile = 1609.344 m). Swap the from and to units with one click and the entire conversion table updates instantly.

Common length conversions

• Meters to feet and feet to meters
• Kilometers to miles and miles to kilometers
• Centimeters to inches and inches to centimeters
• Millimeters, micrometers and nanometers for engineering

Key features at a glance

• Covers metric units from nanometers to kilometers
• Covers imperial units: inches, feet, yards, and miles
• Includes the nautical mile for marine and aviation use
• Live conversion table updates as you type
• Exact results based on the international definition of the meter
• Runs entirely in your browser, even offline

Metric versus imperial length

The world uses two main systems for measuring length. The metric system, used by most countries, is built on the meter and scales cleanly in powers of ten — a kilometer is 1,000 meters, a centimeter is one-hundredth of a meter — which makes conversions within it a matter of moving the decimal point. The imperial and US customary systems, still common in the United States, use inches, feet, yards, and miles with less regular ratios (12 inches to a foot, 5,280 feet to a mile).

Converting between the two systems is where a tool earns its keep, because the ratios are not round numbers. One inch is defined as exactly 2.54 centimeters, and from that single definition every other cross-system conversion follows. This converter applies those exact definitions so a measurement in feet or miles translates precisely into meters or kilometers and back, without the rounding drift that creeps in when you convert by hand.

How the meter became the standard

The meter was originally conceived during the French Revolution as one ten-millionth of the distance from the equator to the North Pole, an attempt to base measurement on nature rather than the body of a king. For most of the twentieth century it was defined by a physical platinum bar, but that approach had limits: a single object can be damaged, and copies drift.

Today the meter is defined by physics itself — the distance light travels in a vacuum in 1/299,792,458 of a second — making it reproducible anywhere in the universe to extraordinary precision. Every length unit this converter handles, metric or imperial, ultimately traces back to that definition, which is why the results are not approximations but exact conversions grounded in an international standard.

Tips for converting lengths

• Remember 1 inch is exactly 2.54 cm — the anchor for all metric/imperial conversions
• A meter is roughly 3.28 feet, handy for quick mental estimates
• Use nautical miles for sea and air navigation, not statute miles
• Reach for millimeters and micrometers for engineering tolerances
• Swap the from and to units to convert in the opposite direction instantly

Why choose our length converter?

Our converter is completely free with no signup, no limits, and no subscription. It runs entirely in your browser, so conversions are instant, it works offline, and the values you enter never leave your device.

It is one of more than 200 free tools on ToopTools, and you can pin it to your My Workspace, a personalized workspace where you arrange the tools you use most into a single dashboard. Beside the other unit converters, it keeps every measurement conversion you need in one convenient place.

Common use cases

People use the length converter for DIY and construction projects where plans mix metric and imperial measurements, for travel when distances are quoted in unfamiliar units, and for schoolwork that asks students to convert between systems. It removes the error-prone arithmetic of cross-system conversion.

Engineers and designers use it for precise tolerances in millimeters and micrometers, sailors and pilots use the nautical mile, and runners and athletes convert race distances between kilometers and miles. Because it shows a full table at once, you see every equivalent without converting one unit at a time.

Is the length converter free?

Yes. It is completely free with no account, no sign-up, and no usage limits. Convert as many lengths as you like at no cost.

How many centimeters are in an inch?

Exactly 2.54 centimeters. This is the internationally agreed definition of the inch, and every other conversion between metric and imperial length is derived from it, which is why the converter's results are exact.

How do I convert meters to feet?

Multiply meters by about 3.28084 to get feet, or simply enter the value in the converter. One meter equals roughly 3 feet 3 inches, a useful approximation for quick mental estimates.

What is a nautical mile and how is it different?

A nautical mile is about 1,852 meters, longer than a statute (land) mile of about 1,609 meters. It is based on the circumference of the Earth and is used in sea and air navigation, where it corresponds neatly to one minute of latitude.

Can it handle very small or very large lengths?

Yes. The converter spans from nanometers, used in science and electronics, up to kilometers and miles, so it works for microscopic measurements and long distances alike.

How do I convert kilometers to miles?

Multiply kilometers by about 0.621371 to get miles, or just enter the value in the converter. As a quick estimate, five kilometers is roughly three miles, which is accurate enough for everyday distance checks.

Are my conversions kept private?

Yes. Everything is computed in your browser and nothing is uploaded, so the values you enter stay private and the tool works without an internet connection.

How do I convert between metric and imperial length units?

Enter a value, pick the unit you have and the unit you want, and the converter instantly shows the result. It covers metric units like millimeters, centimeters, and kilometers alongside imperial units like inches, feet, yards, and miles, so you can switch between the two systems in one step.

Does the length converter work offline?

Yes. The conversion runs entirely in your browser, so once the page has loaded the tool works without an internet connection, and nothing you enter is uploaded — it stays private on your own device.