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Unit Converter

Convert between 200+ units across 9 categories. Instant, accurate, no sign-up.

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0.001

1 Meter (m) = 0.001 Kilometer (km)

Quick Reference

Meter (m)
Kilometer (km)
0.1
0.0001
0.5
0.0005
1
0.001
2
0.002
5
0.005
10
0.01
20
0.02
50
0.05

What is Unit Converter?

A unit converter translates measurements between different unit systems — metric SI, imperial, and US customary. The most common categories include length (meters, feet, inches, miles), weight (kilograms, pounds, stone), temperature (Celsius, Fahrenheit, Kelvin), volume (liters, gallons — note that the UK gallon is 4.546 L while the US gallon is 3.785 L, a difference that matters in cooking and fuel calculations), speed (km/h vs mph), area (square meters vs square feet), and digital storage (bytes, KB, MB, GB, TB). Common confusion points: fluid ounces are a volume unit and weight ounces are a mass unit — they are not interchangeable. Stone is a British unit equal to exactly 14 pounds, rarely used outside the UK and Ireland.

How to use

  1. Select the unit category you need: length, weight, temperature, volume, speed, area, or digital storage.
  2. Enter the value you want to convert.
  3. Select the source unit — the unit your value is currently expressed in.
  4. Select the target unit — the unit you want to convert to.
  5. Read the converted value instantly in the result field.

Why it matters

Unit conversion errors cause real-world failures. The 1999 Mars Climate Orbiter was lost — a $327 million mission — because one engineering team used metric units and another used imperial, and neither caught the mismatch. For everyday use, unit conversion enables cooking recipe scaling between US and European measurements, international travel planning for distances and temperatures, reading product dimensions listed in unfamiliar units, understanding foreign weather forecasts, and comparing fuel efficiency expressed as mpg vs L/100km.

Pro tip

Quick mental math for the two most common conversions: for Celsius to Fahrenheit, double the Celsius value then add 30 (approximate — exact formula is °C × 9/5 + 32). For kilometers to miles, multiply by 0.6 for a close estimate (exact: × 0.621). A 5°C day is roughly 41°F; 100 km is roughly 62 miles. These shortcuts cover most travel and weather conversions without needing a calculator.

Frequently Asked Questions

The unit converter supports 9 categories: length (millimetres to light-years), weight/mass (milligrams to metric tonnes), temperature (Celsius, Fahrenheit, Kelvin, Rankine), area (square millimetres to square miles), volume (millilitres to cubic metres and gallons), speed (metres per second to knots and light speed), time (milliseconds to years), digital storage (bits to petabytes), and pressure (pascals to atmospheres and psi).
All conversions use precise factor-based mathematics derived from official SI definitions. Results are calculated with up to 8 significant figures of precision and rounded only for display. For everyday use, the accuracy is equivalent to professional scientific calculators.
Yes — select the Temperature category, set From to Fahrenheit and To to Celsius, then enter your value. The formula used is °C = (°F − 32) × 5/9. For example, 98.6°F = 37°C. You can also convert to Kelvin (K = °C + 273.15) or Rankine from the same screen.
Fluid ounces (fl oz) measure volume and are used for liquids — for example, a can of soda contains 12 fl oz. Ounces (oz) measure weight or mass. The two units are in different categories: fluid ounces are under Volume and ounces are under Weight. One fluid ounce of water weighs approximately 1.043 ounces, but this varies by the density of the liquid being measured.
You can enter standard decimal numbers and the tool will handle very large or very small values correctly. Results for very large or very small conversions are displayed in standard decimal form where practical. For values in scientific notation, enter the equivalent decimal value (e.g. enter 0.000001 for 1×10⁻⁶).
Over 200 units across 9 categories: length, weight, temperature, area, volume, speed, time, digital storage, and pressure.
Temperature uses offset-based formulas (°F = °C × 9/5 + 32), not simple multiplication factors. It requires special conversion logic.
Yes — all unit conversions work without internet. Only the currency converter requires a connection to fetch live rates.
Multiply meters by 3.28084. For example, 5 meters = 5 × 3.28084 = 16.4042 feet. Select Length category and set From: Meter, To: Foot.