How many KM is a half marathon? Distance, tips and what to expect

If you’re thinking about running your first race, one of the most common questions is simple: how many km is a half marathon?

A half marathon is 21.1 kilometres, or more precisely 21.0975 km. It sits exactly halfway between a 10K and a full marathon, making it a popular distance for both beginner and experienced runners.

Half marathon distance explained

To put it simply, a half marathon is:

• 21.1 kilometres
• 13.1 miles

It’s long enough to be a serious endurance challenge, but still achievable with consistent training.

Why run a half marathon?

The half marathon distance is often seen as the perfect balance between challenge and accessibility.

It allows you to:

• Build endurance without extreme mileage
• Set a meaningful goal
• Improve overall fitness
• Experience race day without the demands of a full marathon

For many runners, it’s the first major milestone.

What to expect during a half marathon

Running 21.1 km is very different from shorter distances.

1. Pacing becomes important. Starting too fast is one of the most common mistakes. A steady pace is key to finishing strong.
2. Energy management matters. Your body will rely on stored energy, so how you fuel before and during the run affects performance.
3. Mental endurance. Beyond the physical effort, a half marathon also challenges focus and consistency, especially in the later kilometres. 

Training tips for a half marathon

Preparing properly makes the distance much more manageable.

 Build distance gradually

Increase your weekly running distance slowly to avoid injury.

Include long runs

Long runs help your body adapt to sustained effort and improve endurance.

Add recovery time

Rest days are essential to allow your body to recover and improve.

Stay consistent

Consistency is more important than intensity when training for a half marathon.

Nutrition and recovery

Fueling correctly plays a big role in how you perform and recover.

Before the race:

• Eat balanced meals with carbohydrates and some protein

After the race:

• Focus on recovery with a mix of protein and carbohydrates

Snacks that are easy to consume and digest can help maintain energy and support recovery.

Is a half marathon beginner-friendly?

Yes, with the right preparation.

Many people successfully complete a half marathon with:

• 8–12 weeks of training
• Gradual progression
• A focus on consistency rather than speed

It’s challenging, but achievable.

Final thoughts

So, how many km is a half marathon? It’s 21.1 kilometres — a distance that offers the perfect mix of challenge and accessibility.

With proper training, pacing, and nutrition, it’s a goal that many runners can reach. Whether you’re aiming to complete your first race or improve your time, the half marathon is a strong and rewarding step in any running journey.