Building from 10k to marathon distance


If you enjoyed training and racing in a 10k, you might want to start looking at a longer run, like a marathon. If you do the maths, a marathon is ‘only’ the equivalent of four 10.5k runs, and having built your confidence on a 10k, that will start to look fairly feasible.


Well, with the right plan and some adjustments to your training, shifting up from 10k to a marathon is completely possible. Use our tips for creating a 10k to marathon training plan to see what you will need to make the shift up to the ultimate long-distance race.

Building a 10k to marathon training plan: all you need to know

A marathon is a very different prospect to a 10k run. You will obviously be running for much longer, at a different speed, and the race itself is much less forgiving. Your training plan will also be very different to what you might have experienced when building up to your first 10k. Nevertheless, it’s perfectly feasible to build up to this distance as long as you take a sensible approach.

How are 10k and marathon training different?

There are several major differences between 10k training and marathon training – some are obvious, others less so:

10k training

Marathon training

  • 3–4 days training per week
  • You run around 25 miles per week
  • Longest training run is around 8 miles
  • 8–10 weeks of training is the norm
  • 4–5 days training per week
  • You run around 45 miles per week
  • Longest training run is around 18 miles
  • 16–20 weeks of training is the norm

How long will it take to go from 10k to a marathon?

The general advice for marathon training is to set aside at least 16 to 20 weeks to train. That said, if you’ve already got a fairly high fitness level (which you probably already have if you’ve trained properly for a 10k), this training time could be shorter – perhaps as little as 12 weeks. Of course, every runner’s training plan will vary, but give yourself at an absolute minimum of three months to prepare.

What’s different about marathon training compared with 10k training?

While the fundamentals of marathon and 10k training are similar, marathon training is a pretty different experience. You’re going to be doing a lot more running – and go farther. Don’t underestimate what impact this will have on your lifestyle – you’ll have to set aside more time in the evening and at weekends to follow your marathon training plan and will find yourself following a stricter marathon diet too.

Here are some of the big differences to be aware of when shifting up your 10k to a marathon training plan:

  • More long, slow runs: A standard marathon training plan (see ours here) will see you doing one long, slow training run each week, which increases incrementally over the weeks of training. This run will normally be over a weekend and see you building up to a peak of 18 to 20 miles three weeks before the marathon itself.
  • Varied speed work: Speed work is a crucial part of marathon training and as you shift up from a 10k to a marathon training plan you’re going to be fitting in at least one speed-training workout per week. This could include Fartlek training, Yasso 800s, interval training or hill sprints – these all boost your endurance and better prepare you to resist exhaustion.
  • Building up base mileage: As you progress through your marathon training plan, your 10k race will start to seem like a walk in the park. Marathon training will see you increase your weekly base running distance to regular 5-mile (around 8k) runs every couple of days.

Take your health seriously

While completing a 10k is still a big achievement, a marathon is significantly longer and more taxing on the body. It’s wise to get a check-up from your GP and, if you’ve got any pain in your feet or legs, make sure you get this treated by a physiotherapist before embarking on marathon training.

Consider investing in new gear

As noted in the table above, marathon training will see you cover many more miles than doing a 10k – in the race itself, but also in terms of weekly runs. As you build up the miles you cover during weekly training, it’s far from unusual to run over 500 miles in just a few months. As a consequence, even the best running shoes and clothing won’t offer total support and comfort. So, consider investing in new running trainers, clothes and accessories .

Creating your 10k to marathon training plan

If you’ve already completed a 10k and have set your sights on the next big goal, a marathon could be the perfect target. If you enjoyed running the 10k, you’ll likely already have a decent base fitness level, and that means shifting up to the marathon training schedule won’t be a huge shock to the system. While there’s no doubt that a marathon is a different, harder race, with the right training and preparation, there’s no reason you can’t make the shift up.