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How to determine your marathon potential from your 5K PB

With this calculation, you can find or structure a training plan around your time

Photo by: Run Calgary

Every year, many runners make the jump to the marathon to experience the satisfaction and joy of completing the prestigious distance. Although running a marathon is much different than running a 5K, there is a calculation tool that could help you figure out your potential, based on your most recent 5K time.

How long does it take to see results from training?

Here’s how to calculate your potential marathon time: take your 5K time and multiply it by 8.5 (the multiplier to get from 5K to the marathon), then add 25 to 30 minutes, depending on the difficulty of the course. 

For example: if you have run a 22-minute 5K, 22 x 8.5 = 187. 187 + 25 = 212 minutes, (which is a 3:32 marathon).

Photo: Toronto Women’s Run

Although this calculation is not always accurate, it can give you a ballpark to train for during the build-up for your first marathon. You will always want to base the calculation on your most recent race result. Therefore, if you break your 5K PB during your marathon training, you’ll want to re-calculate your potential based on your progress/current fitness and then implement the new calculated time into your training and workouts. 

What’s the best temperature for running a marathon?

With this calculation, you can find or structure a training plan around your time. What the calculation does not predict is the mental battle of the final few kilometres in your first marathon. Unfortunately, even with this calculation, you’ll still have to train. 

Here are a few marathons happening around Canada in Spring 2022.