5K & 10K · Guide

Miles vs Kilometers: The Runner's Conversion Guide

One mile is 1.609344 kilometers; one kilometer is 0.621371 miles. The rest of this page is why American runners end up using both at once, and the handful of numbers worth knowing by heart so you never have to do the arithmetic mid-run.

Written for:

By Mike M.Updated November 7, 2026How we pick

#ad

We earn a commission if you buy through our links, at no extra cost to you. It never decides the ranking — the method is published · Affiliate disclosure

The short answer

1 mile = 1.609344 kilometers. 1 kilometer = 0.621371 miles. Those are exact, not rounded: the international mile has been defined as exactly 1,609.344 metres since 1959, which is why the conversion never drifts.

For running, two rough versions are all you need: a kilometer is about six tenths of a mile, and a mile is about one and six tenths kilometers. Everything below is built on those two.

Why runners use both

If you run in the United States this feels like a conspiracy, and the explanation is simply that the two systems arrived from different places. Race distances are metric because competitive athletics is governed internationally — a 5K is five thousand metres, a 10K is ten thousand, and the marathon is 42.195 km. Training logs are imperial because American roads, treadmills and school tracks grew up in miles.

So an American runner ends up training in miles for a race measured in kilometers, and a watch that reports both. There is nothing to fix here — you just need the conversion to be automatic.

The one exception worth knowing: the half marathon and marathon are not round numbers in either system. 13.1 miles and 26.2 miles are themselves rounded from 21.0975 km and 42.195 km.

Every race distance in both units

Race	Kilometers	Miles	Metres
5K	5 km	3.107 mi	5,000 m
10K	10 km	6.214 mi	10,000 m
15K	15 km	9.321 mi	15,000 m
10 miles	16.093 km	10 mi	16,093 m
Half marathon	21.0975 km	13.109 mi	21,097.5 m
Marathon	42.195 km	26.219 mi	42,195 m
50K	50 km	31.069 mi	50,000 m

Our race distances in miles page goes through each of these in more detail, including how long each one actually takes at ordinary paces.

Pace equivalents worth memorizing

This is the table that matters, because pace is where the conversion bites. A pace per mile is slower-sounding than the same effort expressed per kilometer, and people confuse themselves constantly.

Per mile	Per kilometer	5K finish	Marathon finish
7:00	4:21	21:45	3:03:32
8:00	4:58	24:51	3:29:45
9:00	5:36	27:58	3:55:58
10:00	6:13	31:04	4:22:11
11:00	6:50	34:11	4:48:24
12:00	7:27	37:17	5:14:38

Finish times assume you hold that pace the whole way, which almost nobody does — treat them as the arithmetic, not a prediction. If you want to know where a given pace puts you, is a 10-minute mile good? compares it against real race results.

The mental math that actually works

Kilometers to miles: take 60%, then add a bit. 10 km → 6 miles plus a bit (6.2). 21 km → 12.6 plus a bit (13.1). Close enough for every decision you make while running.
Miles to kilometers: add half, then a bit. 6 miles → 9 plus a bit (9.7). 10 miles → 15 plus a bit (16.1).
Pace per km to pace per mile: add 60% of the km pace. 5:00/km → 5:00 plus 3:00 = 8:00/mi. It is exact enough to be useful.
The one to just memorize: a 5K is 3.1 miles, a 10K is 6.2, a half is 13.1, a marathon is 26.2. Those four numbers cover 95% of the conversions a runner ever needs.

Setting your watch

Pick one unit and stay in it. Switching back and forth is where people lose the thread of their own training, because a “good week” in one unit looks like a bad week in the other.

Our advice for US runners: log in miles, race in kilometers, and let the watch do the conversion at the finish line. Every watch below reports distance and pace in either unit, and switches in two taps.

Picks for this job

Watches that handle both units well

Any running watch converts units. These three are the ones we would put a new runner, a 10K runner and a long-distance runner in, and all three let you set distance and pace units independently.

C25K to 10K: the simplest Garmin start
Garmin Forerunner 70
The simplest Garmin start: a 1.2-inch AMOLED touchscreen, Garmin running coach and up to 23 hours of GPS-only tracking. Set it to miles and never think about it again.
$249.99Amazon
#ad · Price as of November 13, 2026 · Affiliate disclosure for the link to Garmin Forerunner 70
C25K to 10K: proven previous-gen pick
Garmin Forerunner 165
The step up for a 10K-to-half runner, with Garmin's training tools and a clear display for pace at a glance.
$197.00Amazon
#ad · Price as of November 13, 2026 · Affiliate disclosure for the link to Garmin Forerunner 165
10K to marathon: long battery, light case
COROS Pace 4
Up to 41 hours with all systems on and 32 g on the nylon band — the one for anyone whose long runs have started to get genuinely long.
$249.00Amazon
#ad · Price as of November 13, 2026 · Affiliate disclosure for the link to COROS Pace 4

If you are still choosing a distance to aim at, the NHS Couch to 5K plan ends at 5 km and Hal Higdon's Novice 10K takes it to 10. Our how long to train for a 10K guide has the timeline.

How we chose these

Researched, compared, scored for your level

We start from what a published training plan actually asks of a runner at your level, compare every model's published specs (stack height, drop, weight, plate, stability features, widths) against that job, and score each pick on a public rubric. Each spec links to where it came from, so you can shortlist in minutes and buy with the numbers in front of you.

Scores are our editorial judgments from that documented research, and rankings are earned on the rubric alone — placement is never for sale. The rubric and weights are on the How We Pick page.

Questions

Frequently asked

How many kilometers are in a mile?

Exactly 1.609344 kilometers. The international mile has been defined as 1,609.344 metres since 1959, so the figure is a definition rather than a measurement. Going the other way, one kilometer is 0.621371 miles.

Is a 5K 3 miles or 3.1 miles?

3.107 miles, which everyone rounds to 3.1. The difference between 3 and 3.1 miles is about 170 metres — roughly 40 seconds at a 10-minute-mile pace, which is enough to matter on a finish time.

How do I convert my pace from kilometers to miles?

Add about 60% of your per-kilometer pace to itself. A 5:00/km pace becomes 5:00 + 3:00 = 8:00 per mile. A 6:00/km pace becomes 6:00 + 3:36 = 9:36 per mile. It is accurate to a couple of seconds, which is well inside the noise of real running.

Should I train in miles or kilometers?

Pick one and stay in it. For US runners we would log training in miles, because that is how roads, treadmills and most American training plans are marked, and let the watch convert at the finish of a metric race. Switching units mid-block is the fastest way to lose track of what your own training is doing.

Why is a marathon 26.2 miles and not a round number?

Because the distance is defined in metric: 42.195 km, which converts to 26.219 miles. It is not a round number in either system, which is why both 42.195 and 26.2 get quoted.

Keep going

Receipts

Sources

Every figure above is traceable. Specs come from the maker's own pages or the named reviewer's published measurements (linked above); level definitions come from published training plans; prices come from Amazon's own API and carry the date they were checked, so you buy on a current number. Read the full method.