Predicting Your Marathon Off Your Half Marathon

Audio Transcript

Coach Sinead: Hi everyone, I am here with you for today’s episode of extra kick brought to you by Runners Connect.

Thank you so much for joining me today. If you have a question you’d like one of our expert coaches to answer in an upcoming episode, you can submit it at runnersconnect.net/daily.

We’d love to help you train smarter and faster. Please don’t hesitate to ask whatever has you curious. Today, we have a question from Jane.

She says, “I’m running a marathon in October and I’d like to know how I should gauge what pace I should run the marathon and what my predicted finish time should be?

I ran a 138 Half Marathon a few weeks ago, as part of my training. How should I be able to work out my predicted finish time for the marathon from that? Thank you very much.

Sinead: This is a fantastic question Jane, and one that we get often at Runners Connect. Fortunately, the easiest and most accurate way to predict your marathon time is off your Half-Marathon time. I know you said your marathon was in October. I hope we haven’t missed it. I hope it’s sometime in the next few weeks and this episode comes to you right in time.

If not, maybe this can help you out for a future race. But I’ve got my fingers crossed that this does make it to you in time.

First off, I want to say that Runners Connect has a race predictor calculator and it’s extremely accurate.

You can plug in your past race times and it will show you all the different distances, what you can run due to your current fitness and what you ran in your most recent race.

If you’re interested in finding this calculator, all you should do is Google race predictor calculator at Runner’s connect and you’ll be able to find it. It will be the first thing right at the top of the page.

Jane, I went ahead and plugged in your numbers.

You said that you ran a 138 marathon a few weeks ago, which by the way, is incredible. That’s a fantastic time and one that does bode well for the marathon.

I plugged that into the calculator and what came up was a 324 marathon and that equals out to an average of about 748 per mile pace.

For you Jane, I think you’re probably a bit more familiar with kilometers, based on your ascent, so that’s more like 451 per kilometer pace.

Given the fact that you average about 728 per mile pace or 434 per kilometer for the Half that you just ran, you’re going to want to add about 20 seconds per mile or 17 seconds per kilometer.

I think that’s really going to feel good and a bit more comfortable. When you’re adding that much time to the mile, sometimes it can be hard to go out at such a conservative pace.

Just know that is going to get you to about a 324 marathon if you do run consistently. This calculator suggests that you are currently capable of a 324 or faster.

It is great that you do have a Half Marathon to go off of here because obviously, the closer the distance to the marathon, the more accurate the prediction will be.

You would really want to use something like a 5K or a 10K time. A Half Marathon is a good reference point for the marathon.

I want to talk a little bit about how this calculator works.

I feel like when you feel like you’re relying solely on some algorithm that you can’t even see, you’re going to be a little bit skeptical, which is understandable for sure.

The way our calculator works is a bit different from a lot of calculators you’ll find on the internet.

They use an algorithm that was published back in 1981 by an engineer named Peter Riegel.

Unfortunately, with these calculators, there’s a lot of room for error because when Riegel made the algorithm for these calculators, there was very little data to work with.

He based his calculator on the performances of World Record holders even though he knew that this probably wouldn’t apply to the average runner.

A few years later, there was some research done by the Bio Med Central and it was led by a man named Andrew Vickers, who was a Sub three-hour marathoner and a cancer statistician at Memorial Sloan Kettering Cancer Center.

Vickers found that most of these pace calculators, that were based on wriggles formula, underestimated correct marathon finish times by 5-20 minutes, which is obviously a recipe for failure so not really something you want from a predictor calculator.

To create a more accurate calculator that was based on the performances of more typical runners, Vickers collected training and race results from over 1,000 recreational marathoners and his subjects had an average marathon finish: 328 for men and 354 for women.

When Vickers ran the numbers, he discovered this discrepancy between his results and other marathon predictor calculators.

For example, a lot of the calculators out there say you plug in your Half Marathon time, maybe two hours and you’re trying to estimate your Marathon time.

A lot of those calculators will give you a prediction of about 407-412. Our calculator, which is based on Andrew Vickers’ algorithm, finds that 417-430 would be a lot more accurate.

In short, a lot of these other calculators will give you prediction times that could be as much as 20 minutes off the mark, and that’s because these are based off of your Olympians and your world record holders.

Vickers algorithm is much more accurate and that’s what we base our calculator off of.

So, Jane, having just done a 138 Half Marathon just a few weeks ago, you should be able to head about 451 per kilometer pace or 748 per mile pace. About a 324 Marathon.

Again, I hope this comes to you in time for your race and I wish you the best of luck.

I hope this really helps. You can find our calculator by just Googling It ‘Runners Connect prediction calculator’ and it will be right at the top of the page there.

Thank you so much again Jane. I hope that helps and best of luck to you.

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We would absolutely love to hear from you and help however we can so please do submit those questions. I hope you join me again next time and until then you have a fantastic day.