Skip to Content

How Many Miles is a 50k? | The Ultimate 50k Ultra Training Guide

Determining how long a 50k is in miles is the first step when committing to a 50k race. Many runners find themselves itching for more after completing a marathon. For those wanting more, the natural next step is an ultramarathon – however, unlike road races, ultras are not all the same distance.

How many miles is a 50k?

A 50k is exactly 31.07 miles. 50 kilometers is not to be confused with 50 miles, which is an entirely different race. 50k is usually the next distance after a marathon (26.2 miles). While the difference in distance might not look like a lot – just about 5 miles longer – those extra miles require a tremendous amount of mental and physical strength.

For most 50km races, the average accepted distance is 31 miles. However, it is possible for some to be closer to 32 miles. The official distance will depend on the specific race itself.

Is 50k an ultra?

Yes, a 50k race is considered an ultramarathon. This is the first recognized distance as an ultramarathon, and the natural next step after a marathon for most runners looking to complete their first ultra.

Most 50k races take place on trails, which makes each race unique. Training is similar to marathon training, but places more of an emphasis on overall training time as opposed to distance. Running a 50k of 31 miles is no easy feat, and certainly worthy of the ultramarathon title.

Any distance over the 26.2 mile marathon is technically considered an ultramarathon. The most common ultras are 50k, 50 miles, 100k and 100 miles.

How many miles is a 50k? This is likely the first of many questions you’ll have as you begin training for a 50k ultramarathon. Here is your ultimate guide!

The Ultimate 50k Training Guide in Miles

Training for a 50k ultramarathon requires grit, consistency, perseverance and strength. It is no easy task. However, when completed after a few marathons, with a solid running base, ultra training is well within the reach of most runners.

Here are some of the most common questions about 50k training, as well as a guide for beginners ready to transition to their first ultramarathon.

How long does it take to train for a 50k?

The length of time it takes to train for a 50k varies from runner to runner, depending on a number of different factors. Base mileage and fitness play a large role in the length of time it’ll take to adequately train for a 50k.

Many runners are able to train in about the same amount of time it takes for them to train for a marathon. This usually requires about 4 – 8 months of training, depending on base fitness when beginning. While training might look similar, there are a few key differences.

How do you train for a 50k?

Training for a 50k might look similar to marathon training in terms of length of time it takes to prepare, but the actual workouts, runs and training style vary quite a bit.

If you are planning to run a road 50k (aka 31.07 miles entirely on the roads), adding 10-15% more volume to your marathon training plan will likely be sufficient in helping you prepare.

However, most 50k ultras take place entirely, or mostly, on the trails. Transitioning from a road marathon to trail 50k for the first time is a significant leap. Trail 50k training will require you to shift your focus from total distance during long runs to total time.

You’ll want to decrease the amount of speed workouts in training and instead add more back-to-back long runs. Slow down your pace, and try to get weekly long runs in on the trails. Your peak long run distance will need to increase slightly as well. If you peaked at 20 miles during marathon training, aim to peak around 22-23 miles for 50k training.

How long does it take to run a 50k?

The length of time it takes a runner to complete a 50k will vary greatly depending on the course and runner. Most trail ultra runners incorporate a great deal of walking to conserve energy going up hills.

The additional walking, as well as a slower pace overall due to the terrain, adds a great deal more time than one might expect if they were running 50k on the roads.

Most runners take anywhere from 6-10 hours to complete a 50k course.

Beginner 50k Training Guidelines in Miles

  • Long run pace: at least 10-30 seconds slower per mile than your marathon pace
  • Training length: 24-30 weeks for beginners
  • Weekly mileage: begin around 20-30 miles per week and gradually build up
  • Long run peak: peaks at 22-23 miles for the longest run
  • Training style: less speed work, more back-to-back long runs to boost weekly mileage
  • Run style: slow and steady, with at least one weekly trail run
  • Running fuel: every 4-6 miles, consume whole, simple foods

When transitioning from marathon training to 50k ultramarathon training, you’ll need to shift your mindset as well. Marathon training often has a focus on speed, with short, fast bursts of efforts. The entirety of training takes place on the roads, and each run is based solely on distance.

In contrast, ultramarathon training requires weekly trail running, a significantly slower pace, higher mileage, more running on tired legs, and less speed work. Hills, trails and strength training all replace the short, fast intervals of marathon training.

You’ll need to maintain regular strength training and incorporate some balance and stability exercises as well. Increase your recovery efforts, get even more rest, and practice fueling your body with real foods.

How to Select a 50k Ultramarathon

The 50k ultramarathon you choose as your goal race has a great deal of impact on how you train and how you’ll perform. Since most 50k races take place on the trails, each race is incredibly different. Some races have difficult terrain while others have a well-worn path. Some races include a great deal of vertical gain, while others are much flatter.

Selecting your goal 50k is a decision not to be taken lightly. There are many factors to research and use in your decision that may not be significant in other road races, like a marathon. Here are some important factors to consider when choosing a 50k ultra.

  • Vertical gain: check the overall vertical gain of the race, as well as the course profile. A good rule of thumb is that every 100m of vertical gain is equivalent to 1k extra time (0.65 miles) – the greater the vertical gain, the longer it will take to complete the race
  • Terrain: all trail races are not the same. Some have a well-worn path that is easy to follow and relatively smooth, while others require running through rocks, stones, sticks and making your own path entirely
  • Weather: while it’s not possible to predict the race day weather months ahead of time, it’s helpful to have a general idea of the typical weather at the race location when the race takes place. Knowing ahead of time whether it is cold or hot, snowy, rainy or humid, will help you make an informed decision. Also keep in mind that in many areas, the weather and temperature changes significantly throughout the course as elevation increases
  • Aid stations: the frequency of aid stations is helpful to know ahead of time, especially for your first 50k. More frequent aid stations can be a source of comfort for runners, and very helpful when the path is uncertain
  • Cut off times: some 50k ultras have cutoff times that might be hard to achieve for your very first ultramarathon
  • Race reputation: selecting a well-known, high profile race is a good idea for your first ultramarathon. These courses usually have a path that is easier to follow, more support along the course, and are generally safer than smaller races
  • Course structure: check ahead to find out how well-marked the course is. When running the trails in mountains or forests, it can be easy to get off course or get lost along the way. Finding an ultra with a well-marked and easy to follow course is a great way to boost confidence during the race
  • Altitude: if you are not used to running and training at altitude, try to avoid races with higher altitudes for your first ultramarathon. The higher the altitude, the more likely for sickness, as your body has to work significantly harder to get oxygen

10 Tips for Training for a 50k Race

While nothing can truly prepare you for a 50k except running the exact race itself, there are a few things you can do during training to help mentally and physically prepare for your best ultramarathon.

  • Incorporate back-to-back weekend long runs
  • Plan course specific training – on the trails
  • Include balance and stability exercises
  • Practice fueling and hydrating
  • Prioritize recovery
  • Train based on time and not distance
  • Invest in quality gear
  • Be realistic when estimating your finish time
  • Allow yourself enough time to train
  • Switch your mindset from marathon to ultra

Fueling Tips for a 50k

Fueling for a 50k ultramarathon is significantly different than fueling for a road marathon. Most marathons provide gels or packaged fuel for the course, whereas ultras provide real foods.

Luckily, in a sense, fueling for a 50k is actually easier than fueling a marathon, since you can bring along foods that you already have at home. Whole, real foods that are simple and easily digestible are key for ultra running.

Popular sources of fuel are candy, potatoes, PB&J, fruits, chips and bread. At aid stations, you might find real food for runners to stop and eat. Bringing along sandwiches and full granola bars – even potatoes – is not uncommon in a 50k.

The key to successful fueling is to eat enough calories frequently, and to practice during training. Experiment with different foods to find what your body responds best to, and then practice during each long run.

50k Gear and Essentials

The gear you’ll need to run a 50k will vary slightly based on the course, but in general, there are a few things all ultra runners should have on hand. Here are some essentials for running your first 50k.

  • Hydration vest
  • Chafing cream
  • Sunblock
  • Hat or visor
  • Packable jacket
  • Trail shoes
  • Fuel!

When you learn how long a 50k is in miles, you might find yourself surprised by how manageable the leap sounds from marathon to 50k. However, venturing into ultra territory – regardless of the distance – welcomes an entirely different running scene.

If you’re ready to complete your first ultramarathon, the 50k is a great first step. Embracing training and all of its differences will help you show up prepared and confident on race day. Do your research, plan accordingly and give your body plenty of practice during training. And be prepared – once you start ultra running, you’ll be hooked!

More tips for 50k ultra training: