Is a 50K considered an ultra marathon?

Yes. A 50K (31.07 miles) is officially an ultra marathon because it exceeds the standard marathon distance of 26.2 miles. It is the shortest and most common ultra distance and the recommended starting point for runners transitioning from marathons to ultra running. Those extra 5 miles beyond the marathon do change the race, requiring adjusted pacing, earlier nutrition intake, and a slightly different mental approach.

How long does it take to run a 50K ultra marathon?

Most recreational runners finish a 50K in 5 to 7 hours on moderate trail terrain. Competitive runners can finish in 3.5 to 4.5 hours. The time depends heavily on terrain, elevation gain, and weather. A flat road 50K is significantly faster than a mountain trail 50K with 5000 feet of climbing. Most 50K races have cut off times of 8 to 10 hours.

What is the longest ultra marathon in the world?

The longest certified footrace in the world is the Sri Chinmoy Self-Transcendence 3100, covering 3100 miles around a single city block in Queens, New York. Runners complete roughly 60 miles per day for 40 to 52 days. Among single stage races, some events exceed 200 miles. The Barkley Marathons covers roughly 130 miles with approximately 60000 feet of elevation gain across five loops in the mountains of Tennessee.

How Many Miles Is An Ultra Marathon? Every Distance Explained

Q: How many miles is an ultra marathon?

An ultra marathon is any running race longer than the standard marathon distance of 26.2 miles (42.195 km). There is no maximum distance. The most common ultra marathon distances are 50K (31.07 miles), 50 miles (80.47 km), 100K (62.14 miles), and 100 miles (160.93 km). Some races go beyond 100 miles, and timed events challenge runners to cover as much distance as possible within 6, 12, 24, or 48 hours.

Q: How long does it take to run 100 miles?

Most runners finish a 100 mile ultra marathon in 24 to 36 hours. Competitive runners can finish in 14 to 20 hours on moderate courses. The course record at Western States 100 is around 14 hours. Most 100 mile races have a 30 to 36 hour cut off time. The Barkley Marathons, widely considered the hardest 100 mile race, has a 60 hour cut off and has been completed by only 20 runners in its history through 2024.

Q: Can you walk during an ultra marathon?

Yes. Walking is expected and strategic in ultra marathons. Nearly every ultra runner walks at some point during a race, especially on steep climbs and through aid stations. Many experienced runners use a deliberate run walk strategy from the start, running flat and downhill sections while walking uphills. As long as you cross the finish line before the cut off time, it does not matter whether you ran, walked, or crawled.

The Short Answer (and Everything Beyond It)

An ultra marathon is any race longer than the standard marathon distance of 26.2 miles (42.195 km). That is the only requirement. There is no maximum distance, no minimum terrain requirement, and no rule about whether you run on roads, trails, or a track. If the race is longer than 26.2 miles, it is an ultra.

The most common ultra marathon distances are 50K (31 miles), 50 miles, 100K (62 miles), and 100 miles. There are also timed events where runners cover as much distance as possible within 6, 12, 24, or 48 hours. Some multi day races exceed 200 miles. The longest certified footrace in the world, the Sri Chinmoy Self-Transcendence 3,100, covers 3,100 miles around a single city block in Queens, New York over 40 to 52 days. But most ultra runners start with a 50K and many never feel the need to go further.

Ultra marathon runners on a mountain trail

Quick Answer

Ultra marathon = any distance over 26.2 miles (42.195 km)
50K (31 miles) is the most common and the best first ultra
50 miles, 100K, and 100 miles are the standard step up distances
Walking is expected and strategic at every ultra distance
Cut off times are generous compared to road marathons

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Every Distance Realistic Finish Times Famous Races Walking in Ultras Picking Your First FAQ Last Updated: April 2026

Distance by Distance

Ultra Marathon Distances Explained

50K

50K (31.07 miles)

The entry point into ultra running. Only 5 miles beyond the marathon, but those 5 miles change the race. Your nutrition strategy matters more, your pacing has to be more conservative, and if you are on trails, the terrain adds time and physical demand that road running does not. Most 50K races have cut off times of 8 to 10 hours. If you have run a marathon, you can train for a 50K in 12 to 16 weeks. This is where most ultra careers begin.

Typical finish: 5 to 7 hours · Cut off: 8 to 10 hours

50 mi

50 Miles (80.47 km)

The distance where ultra running truly separates from marathon running. Fifty miles takes most recreational runners 9 to 14 hours. You will run through multiple meals, experience genuine fatigue that a marathon does not produce, and need a deliberate nutrition strategy of 60 to 90 grams of carbs per hour to avoid bonking. The 50 mile distance has a long history dating back to documented races in the 1590s in northern France, and there are over 300 fifty mile races held annually in the United States alone.

Typical finish: 9 to 14 hours · Cut off: 13 to 16 hours

100K

100K (62.14 miles)

A full day event. Most runners take 12 to 20 hours to finish a 100K, which means running into darkness and dealing with fatigue, temperature changes, and gastrointestinal challenges. The Comrades Marathon in South Africa (roughly 90K) is the most famous race near this distance, with a 12 hour cut off. The 100K is the distance where mandatory gear lists, headlamps, and crew support start to become common.

Typical finish: 12 to 20 hours · Cut off: 16 to 20 hours

100 mi

100 Miles (160.93 km)

The defining distance of ultra running. One hundred miles takes most runners 20 to 36 hours and involves at least one full night of running. You will walk significant portions. You may hallucinate from sleep deprivation. Your feet will swell a full shoe size. You will question every life decision that brought you here. And when you finish, you will understand why people keep coming back. The Western States 100, held each June in California, is the most prestigious 100 miler with a 30 hour cut off. Most 100 mile races have 30 to 36 hour limits.

Typical finish: 24 to 36 hours · Cut off: 30 to 36 hours

Timed

Timed Events (6, 12, 24, 48 hours)

Instead of a fixed distance, timed events challenge runners to cover as much ground as possible within a set time limit. These usually take place on short looped courses (often 1 to 5 miles) with easy access to an aid station on every lap. The winner is whoever covers the most distance. The 24 hour world record stands at 319.6 km (198.5 miles), set in 2022. Timed events are popular because they remove the pressure of cut off times and let you run at your own pace.

Run as far as you can · Looped courses

What to Actually Expect

Realistic Finish Times and Pacing

Ultra runners are slower than marathon runners, and that is by design. Average pace for a 50K on moderate trail terrain is roughly 10 to 13 minutes per mile for recreational runners. At 50 miles and beyond, 12 to 16 minutes per mile (including walking) is common and perfectly normal. The longer the race, the more walking is involved, and average pace slows accordingly.

Interesting trend: Research has shown that average finishing paces in ultra races under 50 miles have slowed by roughly 1 minute 40 seconds per mile since the mid 1990s, reflecting the massive growth in participation among recreational runners. Meanwhile, paces in races over 50 miles have remained relatively stable because those distances still attract a higher proportion of experienced, dedicated runners.

The most important pacing rule in ultra running is to start conservatively. If you go out at your marathon pace in a 50 miler, you will pay for it severely in the second half. A common approach is to run the first third at 85 to 90 percent of your goal effort, the middle third at goal effort, and the final third with whatever you have left. Many experienced ultra runners say the race does not truly begin until the halfway point. For detailed training and pacing advice, see our Complete Guide to Ultra Running.

The Ones You Have Heard Of

Famous Ultra Marathons and Their Distances

Some ultras are famous for their history, their difficulty, or their sheer absurdity. Here are the races that define the sport.

Western States 100 (100 miles)

The oldest and most prestigious 100 mile trail race in the world. Held every June from Squaw Valley to Auburn, California. 18,000+ feet of climbing, 23,000+ feet of descent. 30 hour cut off. The silver buckle (sub 24 hours) and bronze buckle (24 to 30 hours) are iconic ultra running prizes.

UTMB

UTMB (106 miles / 171 km)

The Ultra-Trail du Mont-Blanc is the most famous trail ultra in Europe. A loop around Mont Blanc through France, Italy, and Switzerland with 32,000+ feet of elevation gain. 46.5 hour cut off. Considered the unofficial world championship of trail ultra running. Requires qualifying points from shorter races to enter.

The Barkley Marathons (~130 miles)

Widely considered the hardest ultra marathon in the world. Five unmarked loops through the mountains of Frozen Head State Park, Tennessee, with roughly 60,000 feet of total elevation gain. Navigation by map and compass only (no GPS). 60 hour cut off with a 12 hour per loop limit. Since 1986, only 20 runners have ever finished. In 2024, Jasmin Paris became the first woman to complete all five loops, finishing with just 99 seconds to spare. The 2025 edition had zero finishers.

Hardrock 100 (100 miles)

The high altitude ultra. A loop through the San Juan Mountains of Colorado with an average elevation of 11,000 feet and 33,000+ feet of climbing. 48 hour cut off. Often called the hardest official 100 miler in the United States (the Barkley is unofficial and operates outside traditional ultra running structures).

COM

Comrades Marathon (~90K / 56 miles)

The world’s oldest and largest ultra marathon, held annually in South Africa since 1921. Alternates between “up” and “down” courses between Durban and Pietermaritzburg. 12 hour cut off. Over 20,000 runners participate each year, making it by far the largest ultra marathon field in the world.

For more race options including North American events, see our guide to Popular Ultra Marathons You Should Know About in 2026.

Yes, You Can Walk

Walking in Ultra Marathons

If there is one thing that surprises people new to ultra running, it is how much walking happens. Walking is not just allowed in ultras, it is expected and often the smarter tactical choice. Nearly every finisher of a 100 mile race walks significant portions of the course. Many runners walk all uphills from the very first mile as a deliberate energy conservation strategy.

✓ When to Walk

Steep uphills (power hiking is faster than struggling to run)
Through aid stations while eating and refueling
When your heart rate climbs above zone 3 on long efforts
In the later miles when running form breaks down
Strategically from the start using a run/walk ratio

✗ When Walking Becomes a Problem

Walking flat and downhill sections in the early miles (too slow too soon)
Extended stops at aid stations (muscles cool, harder to restart)
Walking because you went out too fast (pacing error, not strategy)
Walking because you stopped eating (nutrition failure, not fatigue)

A useful practice is to build walking into your training long runs. Practice power hiking uphills, practice eating while walking, and practice transitioning smoothly back into a run after a walk break. The runners who look the most comfortable in the final miles of an ultra are usually the ones who incorporated walking from the start. For a full breakdown of training, nutrition, and pacing strategy, see the Complete Guide to Ultra Running.

Getting Started

How to Pick Your First Ultra Marathon

A 50K is the right choice for your first ultra for most runners. It is only 5 miles beyond the marathon, which means you can train for it without a dramatic change to your weekly mileage, and the race itself is short enough that nutrition mistakes are recoverable and the mental challenge is manageable.

What to look for in a first ultra: Generous cut off time (at least 8 hours for a 50K), well stocked aid stations every 5 to 8 miles, moderate terrain without extreme elevation, a looped or out and back course (so you are never too far from the start/finish if you need to drop), and a supportive community atmosphere. Avoid point to point mountain races for your first attempt.

Once you have a race selected, give yourself 12 to 16 weeks to train. If you are coming from a strong marathon base, you are closer to ready than you think. The biggest adjustments are adding back to back long runs on weekends, starting your nutrition practice on training runs, and slowing your long run pace by 30 to 60 seconds per mile compared to marathon training. For the full training framework, race nutrition protocols, gear lists, and mental preparation strategies, see our Complete Guide to Ultra Running.

You will also want the right gear. Trail shoes are essential if your race is off road (see the Shoe Finder), and a GPS watch with battery life that exceeds your expected finish time is non-negotiable (see the best watches for ultra runners). If your race involves any darkness, a headlamp goes on your mandatory list.

Runner crossing an ultra marathon finish line

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Training plans, nutrition protocols, gear lists, and mental strategies.

Common Questions

FAQ

How many miles is an ultra marathon?

An ultra marathon is any race longer than 26.2 miles (42.195 km). The most common distances are 50K (31 miles), 50 miles, 100K (62 miles), and 100 miles. There is no maximum distance. Timed events (6, 12, 24, 48 hours) challenge runners to cover as much ground as possible within a set time.

Is a 50K an ultra marathon?

Yes. A 50K (31 miles) exceeds the standard marathon distance and is officially an ultra marathon. It is the shortest and most common ultra distance and the best starting point for runners moving up from marathons.

How long does it take to run a 50K?

Most recreational runners finish a 50K in 5 to 7 hours on moderate trail terrain. Competitive runners can finish in 3.5 to 4.5 hours. Time depends heavily on terrain, elevation, and weather. Most 50K races have cut off times of 8 to 10 hours.

How long does it take to run 100 miles?

Most runners finish in 24 to 36 hours. Competitive runners can finish in 14 to 20 hours on moderate courses. Most 100 mile races have 30 to 36 hour cut off times. The Barkley Marathons, the hardest 100 miler, has a 60 hour cut off and only 20 runners have ever finished it.

What is the longest ultra marathon?

The longest certified footrace is the Sri Chinmoy Self-Transcendence 3,100, covering 3,100 miles around a city block in Queens, New York over 40 to 52 days. Among single stage trail races, the Barkley Marathons covers roughly 130 miles with 60,000 feet of elevation gain. The UTMB is 106 miles with 32,000 feet of climbing.

Can you walk during an ultra marathon?

Yes. Walking is expected and strategic. Nearly every ultra finisher walks at some point, especially on climbs and through aid stations. Many runners use a deliberate run/walk strategy from the start. As long as you finish before the cut off time, it does not matter how you get there.

What is the best first ultra marathon distance?

A 50K (31 miles). It is only 5 miles beyond the marathon and most runners with marathon experience can train for one in 12 to 16 weeks. Choose a race with generous cut off times, good aid stations, and moderate terrain. See the Complete Guide to Ultra Running for training plans and race day strategy.

Is running 100 miles a week healthy?

It can be if you build to it gradually over months or years with proper periodization, nutrition, strength training, and recovery. Most recreational ultra runners train at 40 to 60 miles per week. Only elite and very experienced runners regularly train at 100 miles per week. Jumping to high mileage without progressive build up leads to overuse injuries. The 10 to 15 percent weekly increase rule applies at every level.

How Many Miles Is an Ultra Marathon? Every Distance Explained

The Short Answer (and Everything Beyond It)