How Many Miles Is A 100K & How to Train For One

Curious about the 100K race? Then you have come to the right place.

When talking about a 100k race, we’re delving into the world of true long-distance mileage.

In this article, I’ll explain what the 100k race is all about, what it takes to run one, and a few guidelines on how to get started on training.

Sounds great?

Let’s get started

How Many Miles in 100K

So how far is 100K in miles?

Let’s get back to the basics.

One kilometer equals 0.621 miles. So if you multiply 0.621 by 100, you get 62.1 miles.

In other words, a 100k race will have you running 62.1 miles.

That’s a lot of miles.

Still not making any sense?

Let me put that number in perspective.

Running a 100k is the equivalent of running 49 miles more than a half marathon, 36 miles more than a marathon, and over 30 miles more than a 50K.

The race is also the equivalent of 20 5K and ten 10K. Yes, imagine running twenty 5K races in a row. That’s a lot.

The 100k race is considered the gateway distance to the 100-mile race for many ultra runners.

Also known as ultra distance or ultra running, an ultramarathon is any footrace longer than the classic marathon distance of 42.19 kilometers –26 miles.

How long does it Take to Run a 100K?

Overall, the 100K distance may take most runners around 10 to 15 hours to cross the finish line.  This means spending a lot of time running through meal times, cruising in the dark, and spending a whole day on the trail.

But overall, a good 100k time is 09:09:35. If you’re wondering from where I got that number, then know it’s the average 100K time across all ages and genders. A fast 100K time is anything within six hours.

Training For a 100K

It should come as no surprise, but to run such a long race, you’ll need to invest long months—even years—of training.

During your training period, you’ll need to learn more about endurance training, nutrition, injury prevention, recovery, and other aspects so you can maximize your training on all levels.

How To Know If You’re Ready To Train for 100k

Before you jump into 100k training, you’ll want to first have a few ultra-distance races under your belt.

Increasing your training volume over time will grant your body enough either to adapt. Jumping from 5K to 100k is the recipe for failure.

The longer the distance of the race, the more time your body will need to adapt to a higher load. There’s no way around it.

At the very least, have a few 50-mile or 80K races as your starting point. When you follow this recipe, you’ll have to add 20k. Yes, by no means a short distance, but it’s better than making the jump from a shorter distance.

To make sure you’re making the right decision, it’d best to have completed these 50-mile races feeling pretty good.

How to Choose your First 100k

Choose your race wisely to have the best possible first 100K experience.

What do I mean?

When embarking on your first 100k, you’ll want to avoid choosing any event that includes super challenging elements such as altitude conditions or extreme climate.

For this reason, know all of your options. I’d recommend a website such as ultra sign up, where you can check out races. You can search by distance, location, date, and even difficulty.

Train Your Mind

Running a 100K is both a physical and mental challenge. Your mind plays a key role in your approach to training and running such a challenging race.

So if you fail to train your mind as hard as you train your body, you’ll set yourself up for failure.

First, acknowledge that 100k is nothing like the half marathons or marathons you’re completed over the last few years (hopefully).

The rest is details.

Spend More Time On Your Feet

Whether you’re looking to complete or compete in the race, it’s key to expand the time you spend on your feet in preparation.

That’s why hiking is one of the best training methods for building a solid base of endurance leg strength in a low-risk way when it comes to ultrarunning.

More Time On Your Feet

Spending long hours on your feet is key –it’s more important than miles or speed. Your body has to adapt to spending hours and hours on your feet to withstand the challenge on race day.

Long Runs

Whether you’re training for a marathon or a 100K, long slow runs are the bread and butter of endurance training.

You’ll want to do at least one slow long run every weekend.

As a rule, aim to complete at least one 50K a week or so before race day. Serious runners should have already covered more than 70K at one go and done several 50K races recently.

I hate to state the obvious, but you’ll need to build up your long runs in a gradual and structured way instead of trying to log in as many miles in one weekend. Follow some common sense.

Complete your long runs at a comfortable, easy, and conversational pace. It should be around 3 to 4 of your RPE.

You can also try doing back-to-backs, which means running two long runs on consecutive days. This training strategy gets your body adapted to running on tired legs.

Choose A Realistic 100K

Are you looking to run your first 100K race? Then I’d recommend choosing an event course that’s relatively flat, well-supported, and in a comfortable climate and weather.

Leave things such as heat, humidity, elevations, and hyenas for when you’re more experienced. That amazing race through the desert or the jungle or whatever will be there next year—and the year after that—no need to jump stages.

Start at where you’re at—not where you want to be.

Few things are as worse as coming to an ultra race but having to quit halfway through because you weren’t prepared enough. This will prevent you from going again, and you don’t want that.

Build Your Base

It goes without saying, but before you set up to train for an ultra race, you’ll want to build the right pace first.

One of the most common mistakes ultra runners make is failing to build an appropriate foundation to handle the physical and mental demands of ultra racing.

Before you start driving a car, you’ll need to learn how to turn one on, shift gears, etc.

The same logic applies to ultra-distance training.

At the very least, you should be running five times a week pain-free for 6 to 12 months before you even consider signing up for an ultra race.

Trying to skip stages will result in underperformance and injury.

An ultra-running plan is similar to any other running plan. Make sure your runs are easy and not too long—shoot for 45 to 90 minutes, depending on your current fitness and goals.

Aim to complete four to six key long or back-to-back run weekends.

Then once you have a base, add in a weekly long run as you’d for marathon training.

Get your body used to running consistently 18 to 20 miles weekly.

Then a couple of months before the race, increase your long run distance every second or third week.

At the very least, you should peak at around 22-24 miles per long run a few weeks before race day. Then you should work it out for 30 miles about four weeks before race day.

Learn To Fuel

Besides logging enough miles, the most important aspect of endurance training is getting your energy needs met.

That’s why you need to learn how properly fuel your body—otherwise, you’ll be running out of fuel soon, and you don’t want that.

You might get away in a shorter distance without a concrete fueling strategy.

But having a fueling strategy is crucial for the 100K race.

Start by deterring your calorie needs and fluid loss per hour.

Use the following formula to calculate your calorie needs.

Then take this sweat test to determine your hydration needs.

I recommend testing different combinations of foods and products to see what works for you.

Some of these should include:

  • Fruits
  • Gummies
  • Energy bars
  • Gels
  • Sports drinks

Make sure to have found out what works the best for you before race day.

Finding out what works is trial and error, but you’ll find out what works best if you keep experimenting. It’s just a matter of time.

I hate to sound like a broken record, but it’s key to master your fueling and hydration strategy before race day. Your body will require continuous energy to help you get to that finish line.