5K, 10K, Half Marathon and Marathon in Miles (km to Miles)

The short answer

A 5K is 3.11 miles, a 10K is 6.21 miles, a half marathon is 21.0975 km or 13.11 miles, and a marathon is 42.195 km or 26.22 miles (usually quoted as 26.2). To convert any other distance, divide kilometres by 1.609344, or enter the distance in the Length Converter with Kilometer as the From unit and Mile as the To unit.

Race distances in km and miles

Race	Kilometres	Miles
5K	5	3.1069
10K	10	6.2137
Half marathon	21.0975	13.1094
Marathon	42.195	26.2188

These are calculated with 1 mile = 1,609.344 metres, the exact international definition. World Athletics gives the half marathon as 21.0975 km (13.1094 miles), exactly half the marathon distance of 42.195 km.

The common shorthand "3.1 miles" for a 5K and "26.2 miles" for a marathon is rounded. If you are logging a run on a watch or app that shows two decimal places, expect 3.11 and 26.22.

How to convert any distance in the Length Converter

Open the Length Converter.

Type the distance in Value to convert, for example 21.0975.

Set From to Kilometer (km).

Set the second menu to Mile (mi). The result appears straight away: 13.10937873.

Scroll the All Length conversions list to see the same distance in metres, yards and feet as well. Click any row to copy that value.

To go the other way, from miles to km, press the ⇄ swap button or set From to Mile. For example, 13.1 miles is 21.0824 km, which is slightly short of a real half marathon. That gap matters if you plan a route from a rounded figure.

The quick mental formulas

• km to miles: multiply by 0.6214 (or roughly by 0.6, then add a little).
• miles to km: multiply by 1.6093 (or roughly by 1.6).

A fast estimate: 10 km × 0.6 = 6 miles, then add about 3.5% to get 6.2. For 5 km: 3 miles plus a bit gives 3.1.

Pace: min/km to min/mile

Distance is only half the story for runners. If your training plan is in miles but your watch shows kilometres, convert the pace too. Pace per mile = pace per km × 1.609344.

Pace per km	Pace per mile
5:00	8:03
5:30	8:51
6:00	9:39
7:00	11:16

And the other way:

Pace per mile	Pace per km
8:00	4:58
9:00	5:36
10:00	6:13
12:00	7:27

To convert pace by hand, turn it into seconds first. 6:00 per km is 360 seconds. 360 × 1.609344 = 579.4 seconds, which is 9 minutes 39 seconds per mile. The Length Converter does not handle time, so do this step with a calculator.

Finish times at a steady pace

At a steady 6:00 per km:

• 5K: 30:00
• 10K: 1:00:00
• Half marathon: 2:06:35
• Marathon: 4:13:10

Multiply the distance in km by your pace in seconds per km, then convert the total seconds back to hours, minutes and seconds. For the half marathon: 21.0975 × 360 = 7,595 seconds = 2 hours 6 minutes 35 seconds.

Converting a training plan

Training plans are often written in weekly miles, while many watches and apps default to kilometres. Convert the weekly total once and work from that:

Weekly distance	Converted
20 miles	32.19 km
30 miles	48.28 km
40 km	24.85 miles
50 km	31.07 miles

Enter the weekly figure in the Length Converter, or multiply miles by 1.609344 (km by 0.6214). Round to one decimal place; nobody needs to run 32.18688 km exactly. If the plan gives individual runs, convert each one, because rounding a long run from 13.1 to 21 km would cut the half marathon distance short.

Other distances you may see

• 1 mile is 1.609344 km, a common road race and track distance.
• 5 miles is 8.0467 km.
• 15K is 9.3206 miles.
• Ultramarathons are any race longer than a marathon; 50 km is 31.0686 miles and 100 km is 62.1371 miles.

Use the converter for these rather than a rounded mental figure if you are planning fuel, water or a target time.

Common mistakes

• Using 1.6 for precise work. 42.195 ÷ 1.6 = 26.37 miles, which overstates a marathon by about 0.15 miles. Use 1.609344 when accuracy matters.
• Converting pace the wrong way. A pace per mile is always a bigger number than the same pace per km, because a mile is longer. If your converted pace got smaller, you divided instead of multiplied.
• Confusing miles with nautical miles. The converter also lists Nautical mile (1,852 m). Race distances use the ordinary (statute) mile.
• Assuming your GPS distance is the race distance. Watches often record a little more than the certified course because runners do not follow the shortest line around bends. That does not change the official distance.

Related conversions

• Speed in km/h and m/s for treadmill or cycling data: How to Convert km/h to m/s and the Speed Converter.
• Your height for a race registration form: Height in Feet and Inches to cm.