How Many Miles Is an Ultra Marathon? 50K to 100 Miles
An ultra marathon is any footrace longer than a marathon: more than 42.195 kilometres, or about 26.2 miles. Ultras do not have one set distance. The shortest common standard is 50K, which is 31.07 miles.
Ultra distances in milesUltra Marathon Distance Chart: Miles and Kilometres
| Race distance | Miles | Kilometres |
|---|---|---|
| Marathon | 26.2 mi | 42.195 km |
| 50K | 31.07 mi | 50 km |
| 50 miles | 50 mi | 80.47 km |
| 100K | 62.14 mi | 100 km |
| 100 miles | 100 mi | 160.93 km |
The marathon row is included as the reference point. Any race longer than 42.195 km qualifies as an ultramarathon; 50K is the shortest common standard ultra distance.
The short version: anything beyond the official marathon distance of 42.195 km counts as an ultramarathon. Most race calendars use a handful of familiar distances: 50K (31.07 miles), 50 miles, 100K (62.14 miles), and 100 miles.
Does 26.3 miles count? Technically, yes. It is longer than a marathon. You are unlikely to see many organised 26.3-mile races, though. Most standard ultras begin at 50K.
Common Ultramarathon Distances Explained
You will see the same four distances again and again: 50K, 50 miles, 100K, and 100 miles. Do not judge the difficulty by distance alone. A hilly trail 50K can be a tougher day than a flatter race that is several miles longer.
50K
31.07 milesThis is where many runners try their first ultra. It is 7.805 km farther than a marathon, but the terrain can make that extra distance feel much bigger.
50 miles
80.47 kmThe jump from 50K to 50 miles is substantial. You will spend much longer eating, hiking, managing aid stations, and trying not to burn too much energy early.
100K
62.14 milesA 100K is more than twice the marathon distance. Depending on the course and start time, you may be out all day and still be running after dark.
100 miles
160.93 kmAt 100 miles, speed stops telling the whole story. Food, feet, layers, lights, pacing, and the ability to keep moving when you are tired all matter.
Is a 50K an Ultramarathon?
Yes. A 50K is 31.07 miles, about 4.85 miles farther than a marathon. That is enough to make it an ultramarathon.
The number alone can be misleading. A flat road 50K may feel like a longer marathon. Take that same 50K onto steep trails with rocks, mud, and long climbs and you have a very different race.
So although 50K is only about five miles longer than a marathon, it is not always a small step up. You may need to slow the pace, eat more often, hike climbs, and spend much longer on your feet.
Timed, Backyard and Multi-Day Ultramarathons
Some ultras do not give you one finish-line distance at all. Instead, you may race for a set number of hours, repeat the same loop, or cover the distance over several days.
Timed ultras
Runners cover as much distance as possible in a set period. The IAU recognizes records for events including 6, 12, 24 and 48 hours. Longer multi-day timed races also exist.
Backyard ultras
The official backyard format uses a 4-mile, 880-foot loop, which is 6.7056 km. A new loop starts every hour. The event keeps going until only one runner completes one more loop than everyone else.
Stage races
The total distance is split across several days. Runners stop between stages, recover overnight, then start again the next day.
200-mile and multi-day races
Once a race stretches past 200 miles, running is only part of the challenge. You also have to manage sleep, foot care, navigation, gear, food, and several days of changing conditions.
How Long Does an Ultramarathon Take?
There is no single finish time that tells you what to expect from an ultra. A flat road 50K and a mountain 50K are both 31.07 miles, yet one may take hours longer because of climbing, footing, weather, and aid-station stops.
If you already have a finish goal, average pace is more useful than a generic finish-time range. Here are a few examples:
| Distance | Example finish | Average pace |
|---|---|---|
| 50K | 6:00 | 11:35 per mile |
| 50 miles | 12:00 | 14:24 per mile |
| 100K | 16:00 | 15:27 per mile |
| 100 miles | 30:00 | 18:00 per mile |
These are pace examples, not promises about how long your race will take. Walking and time at aid stations are still part of elapsed time. For a race you are actually considering, use the Ultra Marathon Pace Chart, then compare that pace with the course cutoff, elevation profile, and past results.
Can You Walk During an Ultramarathon?
Yes. Walking and power hiking are normal in ultramarathons. On steep climbs, hiking can be faster over the whole race because it saves energy. Runners also walk while eating, moving through aid stations, or taking planned breaks.
You do not need to run every step for the race to count. In a long ultra, a well-timed hike can save enough energy to let you run more later.
What Is the Best First Ultramarathon Distance?
If you are choosing a first ultra, 50K is usually the easiest distance to make sense of. It gets you beyond the marathon without jumping straight to the much longer day that comes with 50 miles or 100K.
Look at the course before you sign up. A runnable 50K with moderate climbing, well-spaced aid stations, and a generous cutoff will usually be more approachable than a technical race with steep climbs and a tight cutoff.
If you are choosing gear for a trail race, see the Best Trail Running Shoes. For races that may run into darkness, compare the Best Headlamps for Ultra Running and Best Watches for Ultra Runners.
