Kilometers to miles converter

Convert kilometers to miles (km to miles) with the exact factor, a conversion chart and worked steps.

Drafted with AI writing toolsUpdated Checked examples: 3

km
Try
Miles
mi
Miles: 6.21371192237 mi
Significant figures: 12; Nearest, ties away from zero
Conversion
10 km = 6.2137119224 mi
1 mi in kilometers
1.609344km

10 km is about 6.2137119224 mi. In the other direction, 1 mi ≈ 1.609344 km.

Kilometers to miles

05010015050100150200250kmmi10 → 6.2137
Km to miles chart Rows: 10
KilometersMiles
10.6214
21.2427
53.1069
106.2137
159.3206
21.097513.1094
42.19526.2188
5031.0686
10062.1371
250155.3428
How it's calculated S
  1. Conversion factor

    1 km=0.621371192237 mi1\ \text{km} = 0.621371192237\ \text{mi}

    Rounded here for display; the calculation uses 50 significant digits.

  2. Multiply

    10×0.621371192237=6.21371192237 mi10 \times 0.621371192237 = 6.21371192237\ \text{mi}

About the kilometers to miles converter

To convert kilometers to miles, multiply by 0.6213711922; to convert back, multiply by 1.609344. For example, 10 km is about 6.213712 mi. Displayed factors and results may be rounded.

Kilometer distances are common on road signs and running routes. Convert the total route length before estimating travel time; distance alone does not include traffic, stops or elevation. Race names may be rounded labels, so use the measured distance when precision matters.

International definition of mile: 1 mi = 5,280 ft = 1,609.344 m. These values are exact.

Both units are defined exactly. Calculations use 50 significant digits and round only for display.

How to convert km to miles

Multiply kilometers by 0.621371 (or divide by 1.609344): miles = km × 0.621371. So 1 km = 0.6214 miles, a 5K race is 3.107 miles and 100 km is 62.14 miles. It applies to any land distance; dividing by 1.609344 gives the exact answer.

Why the factor is 0.621371

Kilometers (km) are 1,000 meters. The international mile, fixed in 1959, is 5,280 feet of exactly 0.3048 m, which makes it 1,609.344 m (NIST).

One kilometer is therefore 1,000 ÷ 1,609.344 = 0.621371192… miles. That decimal never ends, so any multiplier is rounded; six decimals, 0.621371, are off by less than one part in a million.

Kilometers to miles chart

Kilometers (km)Miles (mi)
0.10.0621371192237
0.50.310685596119
10.621371192237
21.24274238447
31.86411357671
53.10685596119
74.34959834566
106.21371192237
21.097513.1093787282
42.19526.2187574565
10062.1371192237

Runners use the 5, 10, 21.0975 and 42.195 km rows most: the 5K, 10K, half marathon and marathon are 3.11, 6.21, 13.11 and 26.22 miles.

Converting a running pace

A pace is time per distance, so it converts the opposite way: multiply a per-kilometer pace by 1.609344. A 5:00 per km pace is 8:03 per mile, because 300 seconds × 1.609344 = 483 seconds.

Multiplying the pace by 0.621371 instead gives 3:06 per mile, faster than the world record for the mile. The running pace calculator converts paces and finish times.

Road signs and speed limits

Road signs in Canada and most of Europe give distances in kilometers: 80 km is 49.7 miles. Speed limits convert with the same factor, so 100 km/h is 62.1 mph; the km/h to mph converter handles speeds.

Cyclists call a 100 km ride a metric century. It is 62.1 miles, against 100 miles for a full century.

Quick estimates

Multiplying by 0.6 is easy but reads 3.4% low: 100 km gives 60 miles instead of 62.1. The 8 km ≈ 5 miles rule (× 5/8) is closer, 0.6% high: 40 km ≈ 25 miles, against an exact 24.85.

Common mistakes

  • Multiplying by 1.609. That converts miles to kilometers. The mile figure is always the smaller number: 10 km is 6.21 miles, not 16.09.
  • Using the length factor for areas. A square kilometer is 0.3861 square miles, the factor squared. The area converter handles km².
  • Converting fuel economy with the distance factor. L/100 km also involves liters and gallons and runs the opposite way to mpg; use the L/100 km to mpg converter.

Miles back to kilometers

The miles to km converter multiplies by 1.609344. For meters, feet and yards, use the length converter.

Worked examples

10 km to mi

Kilometers (km)
10 km
Miles
6.2137119224 mi

Checked against: Exact-fraction computation from the legal unit definitions

100 km to mi

Kilometers (km)
100 km
Miles
62.1371192237 mi

Checked against: Exact-fraction computation from the legal unit definitions

1 km to mi

Kilometers (km)
1 km
Miles
0.6213711922 mi

Checked against: Exact-fraction computation from the legal unit definitions

Questions

How many miles are in one kilometer?

1 km is about 0.6213711922 mi. International definition of mile: 1 mi = 5,280 ft = 1,609.344 m. These values are exact.

How do I convert kilometers to miles?

Multiply by 0.6213711922: 10 km × 0.6213711922 ≈ 6.213712 mi. To convert back, divide by the same factor. The factor shown may be rounded.

How can I estimate kilometers in miles without a calculator?

Multiply by 0.62. This is 0.2% below the exact factor (about 0.6213711922), so 10 km comes out as 6.2 mi instead of 6.2137 mi.

About this calculator

mi=km×0.621371192237\text{mi} = \text{km} \times 0.621371192237

Sources

  1. NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B
  2. NIST Handbook 44, Appendix C: General tables of units of measurement
  3. BIPM, The International System of Units (SI Brochure), 9th edition

Checked against references

This calculator includes 3 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.

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