Half Marathon Training - What Time to Expect?

by Johnathan
(Evans, Ga)

I am a beginner attempting to run my first half marathon. On average, I can run a 10k with a 9 minute mile pace. I run every other day with distances from 3-7 miles depending on the day and time allotted, with cross training on the alternates, and I want to know what an average time for me at 49 and my son who is following my same schedule at thirteen. Thanks in advance.

Answer by Dominique:
Hi there,
Thanks for your question about your upcoming half marathon.

A general rule of thumb for a half marathon time, based on a 10k time is to double it, then add 10-20 minutes.

How much to add depends on your speed. Very fast runners would add about 10 minutes, when you are a bit slower, you need to add more.

A 10k at 9 minute mile pace, gets you to the finish line in about 56 minutes. Double that makes 102. Add 20 makes 122, so just over two hours.

You can test this rule of thumb via the Race Conversion Calculator. Should get pretty close.

However, there is a big condition to being able to use this rule: you have to be doing the right training.

So the predicted half marathon is seen to be within your ability. Whether you make it or not depends on your running training.

Now, you are running three, four times a week which is great. However, the distance of 3-7 miles is a bit low for a half marathon. I am not sure when you are doing your half marathon, so I don't know how much time there is to prepare. But I would suggest getting your longest run up to 10 miles at least, preferably longer.

The first ever half marathon I did was on a maximum of a 10 mile run. Let's just say the last 5k hurt. A lot.

So, increase your mileage and you'll have a much better chance of making it to the finish line in about two hours.

If there is not sufficient time left to increase your mileage, then I would argue that a time of about two hours is too ambitious.

If that's the case, then I would highly recommend taking a more conservative approach to your race, i.e. run slower. It's a long way to the finish line when you run out of fuel half way....

Further recommended reading:

Increasing Mileage Safely - About increasing your mileage and how to do it properly.

Half Marathon Running Program - Half marathon running program for beginners (assumes people have completed a 10k race). You may be able to use some running training ideas out of this schedule.

Hope this helps.
Kind regards,
Dominique