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How fast can you run the marathon? How do you predict your race time? My quick guide..

How fast can you run the marathon? How do you predict your race time? My quick guide.. - Ben Parkes Running

Benjamin Parkes |

I hope everyone is having a great week of training! Half marathon season is nearly here, so lots of us will be racing and practicing for the big marathon day coming up. Good luck! I'll be at the Big Half next week, so come and say hi! 

For this weeks sprint read I wanted to have a quick chat about working out your goal pace. How do you know how fast you might be able to run on the day and what pace to set off at. 

Unless you are a complete new runner, you’ll likely have some race times, even if it’s a parkrun, or a 5k time where you ran flat out in training. So I’d take these as a starting point.  

I'd suggest taking that time and applying the Jack Daniels vDOT calculator values to it. (There are so many websites that will predict race times, this is just the one I like!) https://runsmartproject.com/calculator/ 

Simply enter your race distance at the top, your time and click the blue calculate button. Then click on the ‘equivalent’ tab and it will give you a list of times it thinks you can run races at given your latest effort. 

Everything matches up pretty closely for me. What about you? What does it say you can run?? 


Here’s some other ways you could try as well. 


Multiply your 10k time by 5 for first timers, or by 4.66 for an experienced runner. Hal Higdon came up with this method. Again, it works pretty accurately for me. 


Run a Yasso 800 Workout - usually about 2 1/2 weeks before race day. You simply run 10x 800m, with a 400m jog recovery. Take the average time of your 800m runs to get your goal time. So if you average 3 minutes, 30 seconds for your 800’s… your goal time would be 3h30m.. Or 4 minute average for the 800’s, will give a goal time of 4 hours. etc. Personally not a fan and would avoid.. but kept it in the article as it's so widely known about and someone will ask me if I don't include it! 


Finally it should be noted that (and this is data saying this!) women are generally far better at pacing races than men. Men tend have a significantly slower second half of a race compared to women, who tend to be better at pacing it overall. The is one calculator I also like to look at on the Fetch Everyone page, that gives predicted times for the marathon for Men and Women separately, based on a recent half marathon time. It is based on data from 30,000 marathon and 57,000 half marathon results, to predict correlation between them both. Check it out at https://www.fetcheveryone.com/cms-37 


Oh and one other thing.. Garmin watches with race predictors on. These values are based on a pre-set table, that uses your vo2 max to see where you fit. Which in principle is ok, but calculating vo2 max through your watch might not be very accurate, especially if you use wrist based heart rate.. hence usually optimistic predictions! What does yours say?! 


So there we have it everyone, some things to be thinking about over the coming weeks as we go into half marathon season. And using those times to see what race day might hold. 

Do you use any other methods to see how fast you might run on the day? 

All the best, have a great weekend and see you on Monday!