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How Long Does It Take To Run A 50K?

How Long Does It Take To Run A 50K?

If you’ve just started a 50K training plan, or you’ve planned to sign up for a 50k race, or even if just the thought has wandered across your mind, you might also be considering how long it takes. At roughly 5 miles longer than a marathon, it seems daunting enough to be hesitant to try, but not a large enough leap from the marathon distance to truly drive you away.

Because of this, it might seem like there aren’t many more factors in a 50K to cause you to run that much slower than your current or predicted marathon time. It’s only 5 miles longer, right?

Turns out, there are a few factors to consider. But first, let’s answer the specific question: How long does it take to run a 50k?

Every runner is different in how long it will take to run a 50K, but a safe bet would be to run 10 to 30 seconds slower per mile than your marathon pace. For example, if your best marathon time is 4 hours (9:09/mile), then your predicted 50K would be around 4:50 to 5 hours (9:20/mile – 9:39/mile).

If you have yet to run a marathon, use a race prediction calculator to estimate your finish time based off previous race times. While a race predictor tool is a great general guide for the new 50K-er, as I mentioned above, there are many more factors that will affect your finishing time, whether positively or negatively.

One should never rely on such a tool— you may run slower or faster, regardless of the preparation (or, sometimes, the lack thereof). It’s better to rely on yourself, your training, and your own goals. And if you’re still lost in this 8-kilometer void between marathoner and ultramarathoner, keep reading— I’ll explain preparation, whether or not you can/should walk during the race, and more. 

How do I prepare for a 50K?


A basic training plan for a 50K is not much different from that of a marathon training plan, with perhaps the exception of slightly extended long runs. Just because you’re venturing into the ultramarathon territory doesn’t mean you get to forget about the extras: including speedwork, tempo runs, and strength training into your routine on a regular basis.

Your legs need that pop and strength to get you through the downhill sections, uneven terrain, and late-stage fatigue. The stronger you are, the better.

As far as the speedwork and tempo runs themselves, they don’t need to deviate in terms of distance and/or duration of the workout from marathon speedwork or tempo runs. If your previous marathon workouts has called for, for example, 3-mile reps, then you can add that same workout to your 50K training plan. 

To structure your training weeks/cycles in the months leading up to your first 50K, a good rule of thumb is to complete three weeks/cycles (cycles are typically one week, but some athletes like their training cycles to be longer, and it has its benefits), each cycle building in mileage and/or intensity by around 10% from the previous cycle, then followed by one cycle of a “down week,” where your mileage is dialed back 10-15% and the intensity is reduced.

Also read: What is a Good Trail Running Pace?

This “down week” is to allow your body to recover from the miles you’ve put in; a crucial element in getting stronger. 

In each cycle, it’s imperative that you practice fueling during a long run as you would during a race. They say to never jump into a race trying something new, and if you never practiced your fueling strategy, everything will be new on race day— leaving you susceptible to an upset stomach. 

Ultrarunners are often seen consuming more than just liquids, like you might see in a marathon or shorter. At the aid stations, there are whole foods such as bananas, pretzels, gummy snacks, bagels, even bacon. That’s because the longer you go, the more fuel you need, and the more often you need to consume it. 

Play around with different energy chews, electrolyte mixes, and foods that are easy on your stomach on a few long runs. Expand on what fuels already works for you— if you know Gatorade works for you, try a Gatorade chew. If you’ve had some gummy worms during a race and you felt good, maybe try some real fruit, like a banana. 

And while you’re considering your race fueling, you may also be considering how long your long runs should be. The notion of running longer in training to prepare for longer races is a long-held one, and while it’s important to, at the very least, extend the length or your long run (up to 22-25 miles in a single run), it’s not necessarily the end-all-be-all in ultramarathon training. 

In fact, there are quite a few talented ultrarunners who’s weekly mileage doesn’t average above 70 miles per week. While increasing your mileage does increase your endurance, you need to focus on proper recovery to combat the damage and fatigue on your muscles. 


The more you run and break down your muscles, the more you will need to recover to rebuild them: that includes proper nutrition, massage, epsom salt baths, lots of good quality sleep, and physical and mental rest. Recovery IS training, even when you feel like you’ve been laying on the couch a little too long. 

And recovery is especially important for ultrarunners, given the damage done to your muscles over the course of an ultramarathon is greater than the damage done during a marathon or shorter. And if your race is on the trails (which means that you will be, hopefully, training on the trails to prepare!), your muscles will be even more fatigued.

Patience is the name of the game for ultramarathon recovery. If your body feels overworked, or you feel a twinge of pain anywhere, take a few days completely off or with very light cross training, like biking, swimming, or meditative yoga. Keeping your body healthy and in fighting shape is a long process, and one that cannot be rushed or pushed through when you start hitting your limits. 


Ensuring your fueling your body properly throughout the training process is crucial. As runners, we want to but the best fuel in our tanks, and to do that, we should eat as much natural, homemade food as we can— that means making your own granola versus buying store bought, or opting for a homemade meal rather than grabbing some Panera after work. 

However, it can be tough (and expensive!) to do this, and requires more time out of your day to prepare meals and clean up the aftermath. There are plenty of easy, quick meals that pack that ratio of 60% carbs, 25% fat, and 15% protein recommended for ultra runners. One of my personal favorite cookbooks is Run Fast, Cook Fast, Eat Slow— most recipes don’t take longer than an hour to prepare. 

Or, you can cook versatile foods in bulk for the ability to mix and match you meals— make a batch of rice, chicken, roasted veggies and/or sweet potatoes, overnight oats, granola, etc. at the beginning of the week. That way, when you come back from work or a run, your food is cooked and ready to heat up, dress with some sauces, butters, balsamic vinegars, or whatever else your heart desires, and eat. 

In regards to hydration, and in case you didn’t already know, it’s crucial to not only athletic performance, but also to simply living. Proper hydration helps you feel fuller and flushes out toxins from your body.

You should also aim to drink electrolytes— sometimes water is not enough. And if you’re committed to making all of your own food, you can make your own electrolyte drink— blend together your favorite dark fruit juice, coconut water, water, salt, and a sweetener (like honey or molasses) and enjoy. 

How long should I train for a 50K?

Most races covering nearly all distances suggest at least three months, but for an ultramarathon, err on the side of preparedness and aim for four months, especially if you haven’t raced in a while or been endurance training in a while. 

Ultramarathons take a huge toll on your body. Not simply in terms of damaged muscles, but also in terms of your susceptibility to illness post race. The better prepared you are for your race, and the better care you take of your body, the higher your chances are at a good outcome. 

Do ultrarunners walk?

Yes. Walking is not only accepted, but widely done by nearly every ultra runner. Running for hours on end, especially on trails, rolling or steep hills, and through sometimes crazy weather, it’s almost best to walk sections of the race. As long as you’re moving forward, you are making progress. 

Ultramarathons may seem like the opposite, but they’re not a proud event— runners don’t avoid certain “taboos,” like walking, sitting down at aid stations and socializing, or drinking a Coke mid-race (which many ultrarunners will do and have done during nearly every race). Better to walk than to risk collapsing before the finish line because you refused to walk up that last steep vertical at mile 24 in your 50K. 

If you have a 50K coming up, or you’ve done one before and have some tips for newcomers, let us know! Good luck to you on taking the leap from runner to ultrarunner!

Up Next In Trail Running:

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