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kilometers to miles

Kilometers to miles

Convert kilometers to miles in seconds, useful for travel, running and maps, with the exact factor behind the math: 1 mile = 1.609344 km, no rounding involved.

The exact factor and where it comes from

1 kilometer equals 0.621371 mile, and conversely, 1 mile equals exactly 1.609344 kilometers. That value is not an approximation: it is the official definition of the international mile, fixed by the 1959 International Yard and Pound Agreement among the United States, United Kingdom, Australia, Canada, South Africa and New Zealand, which set 1 yard = 0.9144 meter exactly; since a mile is 1,760 yards, 1,760 × 0.9144 = 1,609.344 meters, with no rounding.
The classic mistake in this conversion is using the rounded 0.62 factor instead of the full 0.621371192... value; over short distances the difference is negligible, but over 1,000 km the rounded result (620 mi) ends up roughly 2.2 km short of the exact value (621.37 mi), a gap that compounds in any long-route calculation.
The mile used here is the statute mile, the standard unit for road and running distances in the United States and the United Kingdom. The nautical mile is a different unit, internationally defined in 1929 as exactly 1,852 meters and used in maritime and air navigation, about 15% longer than the statute mile.
The modern statute mile descends from the English statute mile, defined by the 1593 Weights and Measures Act as exactly 8 furlongs, or 1,760 yards. The word "mile" comes from the Latin mille passus (a thousand paces), a much shorter Roman unit of about 1,480 meters that is not the direct source of today's value.

km → mi examples

5K run

Input: 5 km
Expected output: 3,106855 mi

Classic race distance.

Short trip

Input: 100 km
Expected output: 62,1371 mi

Useful approximation for maps.

Marathon

Input: 42,195 km
Expected output: 26,218757 mi

Official marathon distance, defined by World Athletics; matches the traditional 26 miles and 385 yards.

Full tool FAQ

Which unit categories does the tool convert?

There are fourteen categories: length, mass, temperature, data, time, speed, area, pressure, volume, energy, power, angle, frequency and fuel economy. Each one holds several units, from nanometer to nautical mile, from bit to exbibyte, from pascal to atmosphere, and conversion only happens between units of the same kind, because turning meters into seconds makes no sense.

Can I see the value in every unit at the same time?

Why is converting temperature different from converting length?

What is the difference between MB and MiB (decimal vs binary)?

Why are L/100 km and km/L not just a different factor?

Can I type the conversion instead of using the selectors?

Is the data I type sent to any server?

How do I control rounding and scientific notation?

Frequently asked questions

Where does the 1.609344 factor come from?

From the 1959 International Yard and Pound Agreement, which fixed 1 yard at exactly 0.9144 meter; since a mile is 1,760 yards, the result is 1,609.344 meters per mile, an exact value rather than an approximate measurement.

What mental approximation can I use for quick estimates?

Multiplying km by 0.62 is fine for everyday use, but add roughly 0.2% to the result to get closer to the exact value (0.621371) over distances above a few hundred kilometers.

Is a nautical mile the same thing?

No. The nautical mile is exactly 1,852 meters by international definition from 1929, about 15% longer than the statute mile used in this conversion.

Why does the mile have 1,760 yards instead of a round number?

Because 1,760 is 8 furlongs (an English farming unit for furrow length), of 220 yards each; the definition inherited that agricultural base instead of adopting a round decimal figure.

Next steps

From	To
1 km	0.62137119 mi
2 km	1.242742 mi
5 km	3.106856 mi
10 km	6.213712 mi
20 km	12.427424 mi
50 km	31.06856 mi
100 km	62.137119 mi
1,000 km	621.371192 mi

From

1 km

0.62137119 mi

2 km

1.242742 mi

5 km

3.106856 mi

10 km

6.213712 mi

20 km

12.427424 mi

50 km

31.06856 mi

100 km

62.137119 mi

1,000 km

621.371192 mi

The exact factor and where it comes from

1 kilometer equals 0.621371 mile, and conversely, 1 mile equals exactly 1.609344 kilometers. That value is not an approximation: it is the official definition of the international mile, fixed by the 1959 International Yard and Pound Agreement among the United States, United Kingdom, Australia, Canada, South Africa and New Zealand, which set 1 yard = 0.9144 meter exactly; since a mile is 1,760 yards, 1,760 × 0.9144 = 1,609.344 meters, with no rounding.

The classic mistake in this conversion is using the rounded 0.62 factor instead of the full 0.621371192... value; over short distances the difference is negligible, but over 1,000 km the rounded result (620 mi) ends up roughly 2.2 km short of the exact value (621.37 mi), a gap that compounds in any long-route calculation.

The mile used here is the statute mile, the standard unit for road and running distances in the United States and the United Kingdom. The nautical mile is a different unit, internationally defined in 1929 as exactly 1,852 meters and used in maritime and air navigation, about 15% longer than the statute mile.

The modern statute mile descends from the English statute mile, defined by the 1593 Weights and Measures Act as exactly 8 furlongs, or 1,760 yards. The word "mile" comes from the Latin mille passus (a thousand paces), a much shorter Roman unit of about 1,480 meters that is not the direct source of today's value.

Full tool FAQ

Which unit categories does the tool convert?

Can I see the value in every unit at the same time?

Why is converting temperature different from converting length?

What is the difference between MB and MiB (decimal vs binary)?

Why are L/100 km and km/L not just a different factor?

Can I type the conversion instead of using the selectors?

Is the data I type sent to any server?

How do I control rounding and scientific notation?

Frequently asked questions

Where does the 1.609344 factor come from?

What mental approximation can I use for quick estimates?

Multiplying km by 0.62 is fine for everyday use, but add roughly 0.2% to the result to get closer to the exact value (0.621371) over distances above a few hundred kilometers.

Is a nautical mile the same thing?

No. The nautical mile is exactly 1,852 meters by international definition from 1929, about 15% longer than the statute mile used in this conversion.

Why does the mile have 1,760 yards instead of a round number?

Because 1,760 is 8 furlongs (an English farming unit for furrow length), of 220 yards each; the definition inherited that agricultural base instead of adopting a round decimal figure.