An ultra marathon is any running race longer than the standard marathon distance of 42.2 kilometres (26.2 miles).
There is no fixed upper limit: the most common race distances are 50 kilometres, 50 miles, 100 kilometres, and 100 miles, while some events are timed rather than distance-based, such as 24-hour races. How long one takes depends on the distance, the terrain, and the runner, ranging from around five hours to well over a day.
Key takeaways
- An ultra marathon is anything over 42.2 km (26.2 miles).
- Common distances: 50 km, 50 miles, 100 km, 100 miles.
- Finish times range from about 5 hours to 24+ hours depending on distance and terrain.
- Trail ultras are slower than road ultras because of hills and rough ground.
- Most runners walk the hills: pacing and fuelling matter more than speed.
What Counts as an Ultra Marathon?
Any race beyond 42.2 kilometres qualifies as an ultra, from a 45 km local event to a multi-day stage race.
The term covers a huge range: a 50 km race is only about 8 km longer than a marathon, while a 100-mile race is nearly four marathons back to back. Because the category is so broad, always check the exact distance, elevation gain, and cut-off times before entering rather than assuming all ultras are similar.
Common Ultra Marathon Distances
The standard stepping stones are 50 km (about 31 miles), 50 miles (about 80 km), 100 km (about 62 miles), and 100 miles (about 161 km).
Timed events such as 6-hour, 12-hour, and 24-hour races challenge runners to cover as much distance as possible within the limit, usually on a looped course. Stage races split the distance across several days, with runners covering a set route each day and resting overnight.
How Long Does Each Distance Take?
Finish times vary enormously. A strong runner might complete a flat 50 km in around 5 hours, while a hilly 100-miler can take a mid-pack runner 24 to 30 hours.
Cut-off times are generous by design: many 100-mile races allow 30+ hours, and 24-hour races simply end when the clock does. Walking the hills is normal and expected; even elite ultra runners hike steep climbs to save their legs.
Trail vs Road Ultras
Trail ultras run on footpaths, fells, and forest tracks, where elevation gain, mud, and navigation slow everyone down. A 50-mile trail race with 3,000 metres of climbing can take twice as long as a flat road 50-miler.
Road ultras are faster and simpler to fuel, but the repetitive pounding is harder on joints. Beginners usually find a trail 50 km more forgiving than it sounds, because walking breaks are built into the terrain.
How to Train for Your First Ultra
Build up with back-to-back long runs: a long run on Saturday followed by another on tired legs Sunday teaches your body to keep going when fatigued. Practise fuelling on the move, aiming for 60 to 90 grams of carbohydrate per hour on longer efforts.
Test all your kit, shoes, and nutrition in training, never on race day. Most training plans run 16 to 24 weeks, and many coaches suggest being comfortable running a marathon before stepping up.
FAQ
How long is an ultra marathon in miles?
Anything over 26.2 miles. Common distances are 50 km (31 miles), 50 miles, 100 km (62 miles), and 100 miles.
How long does a 100-mile ultra take?
Anything from 12 hours for elites to 30+ hours for mid-pack runners on tough terrain. Most races set generous cut-off times around 30 hours.
Can beginners run an ultra marathon?
Yes, if you build up sensibly. Many runners go from marathon to 50 km within a year using a structured plan with back-to-back long runs.
Do ultra runners run the whole way?
Rarely. Walking hills, aid stations, and tough patches is standard practice at every level, including among elites.
What is a 24-hour race?
A timed ultra where runners cover as much distance as possible in 24 hours, usually on a looped course. You can rest, eat, and sleep whenever you choose.
How do I fuel during an ultra?
Aim for 60 to 90 grams of carbohydrate per hour from gels, chews, or real food, plus electrolytes and plenty of water. Practise your strategy in training.
