Length Conversion

Kilometers Converter (km)

Convert kilometers to metric, imperial, survey, astronomical, and Earth–Moon reference distance units. Enter a value in km, select a target unit, and get instant results with a clear formula.

1 km = 1000 m (exact) 1 mi = 1.609344 km (exact) 1 km = 0.621371 mi 1 nmi = 1852 m (exact) Earth radius ≈ 6371 km Moon distance ≈ 384,400 km
What is a kilometer?

The kilometer (km) is a metric unit of length equal to 1000 meters. It is widely used for travel distances, maps, and science.

Imperial and nautical units

Miles and feet appear in US contexts, while nautical miles are used in marine and aviation navigation. This converter supports all three systems.

Reference distances

Earth radius and Moon distance are helpful for scale intuition. They are reference values, so results are approximate by design.

Kilometers to Anything Converter

Choose your target unit, enter kilometers, then copy the result. Use Swap to invert quickly.

How this conversion works
Kilometers → meters → target unit

This page uses the meter (m) as the base unit. First it converts km to meters, then meters to your selected unit.

Base unit: meter (m)
Plain language

Kilometers are great for "human scale" distances like city travel and road trips, while meters and centimeters help for shorter distances and measurements.

Common formulas

m = km × 1000
mi = km ÷ 1.609344
ft = km × 3280.839895

Real world uses

Maps, GPS, running distances, engineering drawings, science education, aviation and marine navigation.

Tip: You can type commas (like 10,000). The converter reads it as 10000.

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Enter a value to convert
Conversion Formula
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Notes: Extremely large units (light years, AU, parsecs) will display using scientific notation. Earth radius and Moon distance are reference values, so results are approximate.

Comprehensive Conversion Chart

Quick reference table showing common kilometer conversions to major units.

Kilometers (km) Meters (m) Miles (mi) Feet (ft) Nautical Miles (nmi)
0.1 100 0.0621371 328.084 0.053996
0.5 500 0.310686 1640.42 0.269980
1 1,000 0.621371 3,280.84 0.539957
2.5 2,500 1.553428 8,202.10 1.349892
5 5,000 3.106856 16,404.2 2.699784
10 10,000 6.213712 32,808.4 5.399568
50 50,000 31.06856 164,042 26.99784
100 100,000 62.13712 328,084 53.99568
1000 1,000,000 621.3712 3,280,840 539.9568

Metric System (Base 10)

The metric system uses powers of 10, making conversions straightforward and logical.

Metric Prefixes
• kilo (k) = 1,000×
• centi (c) = 0.01×
• milli (m) = 0.001×
• micro (μ) = 0.000001×
1 Kilometer Equals:
• 1,000 meters
• 100,000 centimeters
• 1,000,000 millimeters
• 1,000,000,000 micrometers

Imperial System (Mixed)

The imperial system uses various conversion factors, making it less intuitive but still widely used.

Common Conversions
• 1 mile = 5,280 ft
• 1 yard = 3 feet
• 1 foot = 12 inches
• 1 mile = 1.609344 km
1 Kilometer Equals:
• 0.621371 miles
• 3,280.84 feet
• 1,093.61 yards
• 39,370.1 inches

Visual Scale Comparison

Understanding kilometer distances in real-world context.

1 km About 10 city blocks or a 12-minute walk
5 km A typical 5K run or 1-hour walk
10 km A half-marathon distance
42.195 km A full marathon distance
160 km Typical distance between major cities
6,371 km Earth's mean radius

Worked Examples

Quick examples help visitors verify conversions and understand scale.

Example: km to meters

Convert 3.2 km to m.

Result: —

Formula: 3.2 × 1000 = 3,200 m

Example: km to miles

Convert 10 km to mi.

Result: —

Formula: 10 ÷ 1.609344 ≈ 6.214 mi

Example: km to Moon distance

Convert 50,000 km to "Moon distance".

Result: —

Formula: 50,000 ÷ 384,400 ≈ 0.130 LD

Example: km to feet

Convert 2.5 km to ft.

Result: —

Formula: 2.5 × 3,280.84 ≈ 8,202.1 ft

Example: km to nautical miles

Convert 100 km to nmi.

Result: —

Formula: 100 × 1000 ÷ 1852 ≈ 53.996 nmi

Example: km to Earth radius

Convert 12,742 km to Earth radius.

Result: —

Formula: 12,742 ÷ 6,371 ≈ 2.0 R⊕

History of the Kilometer

The kilometer was established as part of the metric system during the French Revolution. It was defined as 1/10,000th of the distance from the North Pole to the Equator along the Prime Meridian. Today, it's defined in terms of the meter, which is based on the speed of light.

The metric system was revolutionary because it used a base-10 system, making conversions much simpler than imperial units which use arbitrary multipliers like 12, 3, 5,280, etc.

Why Use Kilometers?

Kilometers are ideal for measuring longer distances because they avoid very large numbers. A 10-mile drive becomes a manageable 16 km. They're standard in:

  • • Road signs & navigation: Most countries display distances in km
  • • Sports: 5K runs, marathons (42.195 km), cycling races
  • • Aviation & Marine: Altitude and distance measurements
  • • Science: Astronomical distances and geological scales

Kilometer vs Mile: The Difference

One mile equals exactly 1.609344 kilometers. This means:

  • • 1 km = 0.621371 miles
  • • Kilometers are smaller, so distances appear larger in km
  • • A 100-mile journey is about 161 km
  • • Miles are primarily used in the US, UK (historically), and a few other countries

Astronomical Scales

Kilometers become impractical for space distances, so astronomers use:

  • • AU (Astronomical Unit): Average Earth-Sun distance (149.6 million km)
  • • Light Year: Distance light travels in one year (9.461 trillion km)
  • • Parsec: Used for stellar distances (3.086 trillion km)
  • • The Moon is about 384,400 km away on average

FAQ

Is km to m always exact?

Yes. 1 kilometer is exactly 1000 meters because it is defined by the metric prefix kilo.

What does "Earth radius" mean here?

It is a reference scale using a common mean Earth radius of 6371 km. Real Earth radius varies slightly with latitude.

What does "Moon distance" mean here?

It is a reference scale using an average Earth–Moon distance of 384,400 km. The actual distance changes over the Moon's orbit.

How accurate is the km to miles conversion?

The conversion factor of 1 mile = 1.609344 km is exact by international agreement. Results are accurate to the precision of your input.

Why do some countries use miles instead of kilometers?

Historical reasons. The US, UK (historically), and a few other nations adopted imperial units before the metric system became standard. The US has not officially adopted the metric system, though it's used in science and medicine.

What's the difference between nautical miles and regular miles?

A nautical mile (1852 m) is based on Earth's circumference and is used in aviation and marine navigation. A regular mile (1.609344 km) is used on land. 1 nautical mile ≈ 1.15078 regular miles.