How Long Does It Take to Run 100 Miles?

paces are actually slowing down. According to marathon, which is most often completed on the road, how long it takes to run 100 miles can vary wildly, whether you’re at the front or the Buffalo Run 100.

That’s because each race is so different. Case in point: When I raced the Outlaw 100 in February of 2022 in Oklahoma, it was almost entirely singletrack, meaning the trail was very narrow, rocky, rooted, and difficult. I ran through freezing cold temperatures and nearly 16 hours of darkness. But, I won it in 23:53:42, breaking the men’s and women’s course record by more than three hours.

The next 100 I completed, Sulphur Springs in Ontario, was in May 2025 with nice springtime temps and plenty of light, on mostly doubletrack trails, meaning the trail was gravel but largely smooth and easy to run. I finished in 17:22:46, in third place overall and winning the women’s race.

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Two wins, one course record, and a finish time within three minutes of the standing course record… but with more than six hours separating the finish times.

All that is to say, different courses will have different finish times based on terrain, weather, time of year, and of course, you as a runner and how your body handles that course, that day.

But to help you get a better understanding of what it truly takes to go the triple-digit distance, I dug into the numbers and chatted with David Roche, run coach and the Leadville 100 men’s course record holder (a major 100-miler in the U.S.). Here’s how to know if you can handle your first 100-miler.

Ultrarunning has exploded in popularity with a 1,676 percent increase in participation in the last 23 years, per a RunRepeat report published in 2020. As participation continues to increase, records are dropping fast.

For example, both the men’s and women’s Advertisement - Continue Reading Below were broken in summer 2025. Anne Flower set the women’s course record at 17:58:19, with an average pace of 10:46. Roche set the men’s course record, averaging a 9:07 pace and finishing in 15:12:30.

On a global scale, in 2022, Aleksandr Sorokin finished Spartanion in 10:51:39 setting the 100-mile men’s world record, with an average pace of 6:31. That same year, Camille Herron finished the USATF 100-mile Championships in 12:41:11 setting the women’s world record, with an average pace of 7:36. But these records were set on flat road courses.

For 100 mile trail races, the times are significantly slower: Roche’s win time and record-setting performance in Leadville was more than four hours slower than Sorokin’s 100.

The women’s and men’s current course records at in 2023 average pace 9:17, the other major 100-miler in the U.S., stand at 14:09:28 set by Jim Walmsley in 2019 (average pace 8:29) and the women’s at 15:29:33 set by Courtney Dauwalter in 2023 (average pace 9:17).

With more mass participation, the record times for all ultramarathons may continue to get faster, but the average Nutrition - Weight Loss RunRepeat, the average mile pace for all ultramarathoners in 1996 was 11:35. In 2020, that average stood at 13:16.

For 100-milers specifically, there is very little data on the average finish times or paces. Ultrarunning magazine published stats in 2014, with the men’s average finish time at 28 hours and 8 minutes (16:53 pace) and women’s at 28 hours and 34 minutes (17:08 pace).

While RunRepeat didn’t give average times, the 2020 report mentioned the difference between men’s and women’s pace for 100 milers was just 0.25 percent, demonstrating that the farther the distance, the smaller the gender gap.

It’s important to note that pacing varies greatly over the course of a 100-miler, especially on a trail. Researchers looking at Western States finishers found pacing varied largely based on gender, elevation, and environmental conditions, and the pace was likely to slow in the Download Your Training Plan.

So if you are racing a 100, don’t expect to stick to that 12:30 pace mile after mile. It’s more likely that you’ll run a 10:00 pace followed by 15:00, which makes smart pacing—whether you’ll be chasing a cutoff time or a course record—even more critical.

Your finish time can depend on the race and the course cutoffs. Some are pretty aggressive: For instance, both the Leadville 100 and Western States races have a 30-hour cutoff that makes it pretty much impossible to walk Run Longer: Break New Barriers Outlaw 100 in Oklahoma or The 2025 Marathon and Half Marathon Calendar in Utah, offer 48- and 34-hour cutoffs respectively, meaning someone hiking it with a good amount of hustle and maybe a few jogging How Long Does It Take to Run 100 Miles.

Roche can attest that even the same race will lead to a different finish time from year to year. In his second attempt at Leadville in 2025 (his first go was in 2024), he bested his record from the year prior by more than 15 minutes. Part of the reason was because the temperature was a bit cooler, making it easier to stay fueled and hydrated, he says. Course knowledge and shifts in mentality also played a major role, as did the simple fact that he had more ultra experience than the year before.

Also, too many people lose the race in the aid station, Roche says, because even for faster runners, a few slow aid stations can add up, and it takes experience to hit them quickly.

During my first 100-miler, I spent just over an hour in aid station time, but during my second, only 14 minutes. Again, the weather was different, the course was different, and my needs were different due to those factors, but I still learned to speed up those stops.

The course’s topography and how you tackle it will also affect your finish time, Roche says. Obviously the more elevation gain, the more likely you’ll slow down. If you can’t run up the hills, using them as an opportunity to hydrate and fuel, while still hiking as briskly as possible, will help you power through the miles. Conversely, downhills provide free speed.

Pacing throughout the race matters, too. It won’t be perfectly consistent, but the faster you can move in the daylight hours and while your legs are fresh, the more you’re able to slow down later. But you still have to be careful to not overdo it early on in the race.

Almost anybody can do 100 miles. If you can run 10 miles, you can run 100 miles. But you have to be persistent, says Roche. “There’s the cliche of being willing to occupy the pain cave, and it’s true,” he says.

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Throughout those two years, you should be running regularly, at least three to four times a week, with a 10-mile run feeling easy, Roche says. And because 100-mile races do involve higher volume—usually at least 50 miles per week—you want to ensure that you’re injury-free before ramping up your mileage.

Roche recommends racing at least one 50-miler before doing 100, and finishing that 50 several months or even a year prior to hitting triple digits. This not only improves your endurance, but allows you to test things like shoes, poles, packs, report published in 2020. As participation continues to increase, records are dropping fast.

Personally, I did a 100K (about 62 miles) point-to-point run with a few friends seven months before my first 100, and that “casual” experience was incredibly helpful for dialing in things like my nutrition and anti-chafing strategies. Had I skipped that step, I don’t think my first race would have gone as well.

Defining your “why” is another crucial step in tackling 100 miles. The reason behind why you want to slog out the mileage—which will inevitably involve a lot of discomfort, a lot of pushback from your body, and a lot of questioning how and if you’ll make it to the finish line—is key.

Is your why strong enough to push through those hours of discomfort?

“You need to be invested in the process of it, not just saying you went 100 miles, but the whole experience, because it’s a spiritual experience as much as a physical one,” Roche says. “And the reason it’s a spiritual experience is because it rips you down physically as much as anything can. It will feel emotionally impossible, because your body is torn down to its core. And you know, when you’re torn down to your core, you have to really want to do the thing to keep going.”

Every time I want to quit—before or during a race—I come back to my why. It’s pretty simple: Women are still underrepresented in ultrarunning and I want to inspire the next generation of athletes by being on the start line and, even if the race doesn’t go my way, giving it my all.

Anytime I want to drop out, I think about when I gave a bag of gently-used clothes to my honorary niece a couple of months ago. “Molly may have worn these shorts when she won her race,” my friend Kate told her 11-year-old daughter. Kate told me later that her daughter looked thrilled and the next day, she was out at soccer practice sprinting across the field rocking those shorts, feeling speedy and psyched to run.

Molly Hurford

Contributing Writer

Molly writes about cycling, nutrition and training with an emphasis on bringing more women into sport. She's the author of nine books including the Shred Girls How to Run Longer How Long Does It Take to Run 100 Miles. She co-hosts back of the pack and spends most of her free time biking and running on trails, occasionally joined by her mini-dachshund.