Length Converter - Distance & Length Unit Converter

Metric Units: Meters, Kilometers, Centimeters, Millimeters

The metric system is the international standard for length measurement, officially known as the International System of Units (SI). The base unit is the meter (m), defined as the distance light travels in a vacuum in 1/299,792,458 of a second. Metric units are decimal-based, making conversions simple: just multiply or divide by powers of ten. To convert meters to kilometers, divide by 1,000. To convert centimeters to meters, divide by 100. To convert millimeters to centimeters, divide by 10. This elegant simplicity is why most of the world uses metric.

Practical examples: A standard door is about 2 meters tall. A marathon is 42.195 kilometers. A smartphone is roughly 15 centimeters long. A paperclip is about 30 millimeters wide. The metric system is used in science, medicine, manufacturing, and everyday life everywhere except the United States (which still primarily uses imperial units for daily measurements but uses metric in science and many industries).

Imperial Units: Feet, Inches, Yards, Miles

The imperial system (also called US customary units) evolved from English units and is still the primary system for everyday measurements in the United States. It is also partially used in the United Kingdom, Canada, and other Commonwealth countries. Unlike metric, imperial conversions involve non‑decimal factors: 1 foot = 12 inches, 1 yard = 3 feet, 1 mile = 5,280 feet. This makes manual conversion more cumbersome, which is where a feet to meters converter or inches to cm converter becomes essential.

Common imperial length examples: A typical ceiling height is 8 or 9 feet. A standard sheet of paper is 8.5 × 11 inches. A football field (including end zones) is 120 yards long. A marathon is 26.2 miles. Our tool makes it easy to convert feet to meters (multiply by 0.3048), convert inches to cm (multiply by 2.54), and convert miles to km (multiply by 1.60934).

Nautical Miles: Maritime and Aviation Navigation

A nautical mile (nm) is a unit used in maritime and air navigation. It is defined as exactly 1,852 meters (about 1.1508 statute miles). Unlike the statute mile, the nautical mile is based on the Earth's circumference - one nautical mile equals one minute of latitude. This property makes it extremely useful for navigation charts and GPS coordinates. Knots (nautical miles per hour) are the standard speed unit for ships and aircraft. Our converter allows you to convert nautical miles to kilometers or convert nautical miles to miles instantly.

Astronomical Units and Light Years: Cosmic Distances

For distances beyond Earth, astronomers use specialized units. The Astronomical Unit (AU) is the average distance between Earth and the Sun: approximately 149.6 million kilometers (92.96 million miles). It is ideal for describing solar system distances. For example, Jupiter orbits at about 5.2 AU, and Neptune at 30 AU.

A light year (ly) is the distance light travels in one Julian year (365.25 days) - about 9.46 trillion kilometers (5.88 trillion miles). It is used for interstellar and galactic distances. Proxima Centauri, the nearest star, is 4.24 light years away. The Milky Way galaxy is about 100,000 light years across. To convert AU to light years, divide by 63,241. To convert light years to km, multiply by 9.46073 × 10¹². Our length converter handles these enormous scales with ease.

How do I convert meters to feet?

To convert meters to feet, multiply the meter value by 3.28084. For example, 5 meters × 3.28084 = 16.4042 feet. Conversely, to convert feet to meters, divide by 3.28084 or multiply by 0.3048. Our tool does this automatically.

How many centimeters are in an inch?

One inch equals exactly 2.54 centimeters. This is a defined conversion, so it is exact for all purposes. To convert inches to cm, multiply by 2.54. To convert cm to inches, divide by 2.54.

What is the formula for converting kilometers to miles?

To convert km to miles, multiply the kilometer value by 0.621371. For example, 10 km × 0.621371 = 6.21371 miles. To convert miles to km, multiply by 1.60934. Our km to miles converter handles this instantly.

How accurate is this length converter?

Our converter uses exact conversion factors based on international standards (e.g., 1 in = 2.54 cm exactly). It displays results to 6 decimal places, far exceeding typical needs. For most practical purposes - construction, travel, education - this provides excellent precision.

Can I use this length unit converter offline?

Yes. Once the page has loaded, all conversion logic runs locally in your browser using JavaScript. No internet connection is required, making it reliable anywhere.

What is the difference between a nautical mile and a statute mile?

A statute mile (the common "mile" on roads) is 5,280 feet or 1,609.344 meters. A nautical mile is 1,852 meters (about 6,076 feet). Nautical miles are used in navigation because they correspond to one minute of latitude on Earth's surface, simplifying chart calculations.

How many light years is 1 AU?

One Astronomical Unit (AU) is approximately 0.0000158 light years. The exact relationship is: 1 ly = 63,241 AU, so 1 AU = 1/63,241 ≈ 1.581 × 10⁻⁵ ly. Our astronomical unit converter handles this easily.