How Many Miles Is a 5K, 10K, Half and Full Marathon? (+ Pace Charts)

A 5K is 3.11 miles, a 10K is 6.21 miles, a half marathon is 13.11 miles, and a full marathon is 26.22 miles (42.195 km exactly). Every race distance below, with pace charts and the odd royal history of the 26.2 — and for any other distance, the km to miles converter gives exact numbers in your browser.

Every race distance, both units

Race	Kilometers	Miles	Track laps (400 m)
Mile	1.609	1	4.02
5K	5	3.107	12.5
10K	10	6.214	25
15K	15	9.321	37.5
10 miles	16.093	10	40.2
Half marathon	21.0975	13.109	52.7
Marathon	42.195	26.219	105.5
50K ultra	50	31.069	125
100 miles	160.934	100	402

The conversion behind the table: 1 km = 0.621371 miles (1 mile = 1.609344 km exactly, from the 1959 international yard definition). Quick estimate: multiply kilometers by 0.6 and nudge up.

Why a marathon is 26.2 miles: blame the royal box

The original Olympic marathons honored Pheidippides’ legendary run from Marathon to Athens — roughly 40 km, and the early races varied. At the 1908 London Olympics, the course was laid out to start on the lawn of Windsor Castle (so the royal children could watch) and finish in front of the royal box at White City Stadium: exactly 26 miles 385 yards. After years of varying distances, the IAAF standardized that quirk in 1921 as the official marathon: 42.195 km / 26.219 miles.

Pace conversion: min/km vs min/mile

US runners think in minutes per mile; most of the world in minutes per kilometer. Since a mile is 1.609 km, min/mile = min/km × 1.609:

min/km	min/mile	5K finish	10K finish	Half	Marathon
4:00	6:26	20:00	40:00	1:24:23	2:48:46
5:00	8:03	25:00	50:00	1:45:29	3:30:58
6:00	9:39	30:00	1:00:00	2:06:35	4:13:10
7:00	11:16	35:00	1:10:00	2:27:41	4:55:22
8:00	12:52	40:00	1:20:00	2:48:47	5:37:34

Reference points: the marathon world records sit near 2:00–2:10 (a scarcely believable ~2:52/km); a 4-hour marathon — the most common amateur goal — is 5:41/km (9:09/mile); most beginner 5K plans target the 30–40 minute band.

Treadmill settings: km/h, mph and pace

Treadmills speak speed (km/h or mph), runners think pace (min/km or min/mile). The crosswalk:

km/h	mph	min/km	min/mile	Feels like
6	3.7	10:00	16:06	brisk walk
8	5.0	7:30	12:04	easy jog
10	6.2	6:00	9:39	steady run
12	7.5	5:00	8:03	tempo
14	8.7	4:17	6:54	fast
16	9.9	3:45	6:02	racing

Traveling and the hotel treadmill is in the “wrong” unit? km/h to mph sorts it in a keystroke. (Physiology footnote: a 1% incline is commonly used to approximate outdoor effort.)

Common conversion mistakes runners make

1. Multiplying pace by 0.62 instead of 1.61. Distances shrink from km to miles; pace numbers grow (fewer, longer miles). A 5:00/km runner is at 8:03/mile, not 3:06.
2. Treating “13.1” as exact. The half is 13.109 miles — over a full race, GPS watches showing 13.15 are measuring your tangents, not lying.
3. Comparing 5K road and 5,000 m track times directly. Same distance, but track racing is typically faster — no turns lost, measured line, no crowd weaving.
4. Trusting GPS over certified courses. Race courses are measured along the shortest possible path; you inevitably run slightly farther, so your watch reading past the official distance is normal.

Quick summary

5K = 3.11 miles, 10K = 6.21, half marathon = 13.11, marathon = 26.22 (42.195 km — a distance we owe to the 1908 royal box, not round numbers). Convert distances with ×0.621, but flip for pace: min/mile = min/km × 1.609. For treadmills, dashboards and any odd distance, the km to miles converter has the exact figure.

Distance conversions use the exact 1959 definition (1 mile = 1.609344 km), verified in our public test suite. Related tools: miles to km · km to miles · minutes to hours for total-time math.