How accurate is the race predictor?

For distances close to the race you enter, the prediction is fairly accurate. The bigger the gap in distance, the more your training specificity matters. Treat longer predictions as ambitious targets.

Which race should I enter?

A recent, well-run race of 5K or longer gives the best basis. The closer the entered distance is to your target distance, the more reliable the prediction.

Why is my predicted marathon slower than 8 × my 5K?

Because your speed drops as distance grows — you cannot hold 5K pace over a marathon. The predictor uses a scientific model (Riegel/Daniels) that factors in that decline.

Can I predict a custom target distance?

Yes. Alongside the standard distances you can enter a custom distance, for example 15 km or a 30 km trail, and get the matching predicted time.

Race time predictor — predict your 5K to marathon

Recent race

Pick your distance

Enter your time or pace

Finish time

Pacemin / km

Enter your details to see the result.

Next step

Turn your numbers into a plan

A free personalized plan from 5K to marathon, matched to your level and your week.

Build a free plan

How it works

How do you predict a race time?

The predictor first calculates your VDOT from the performance you enter, then looks up the times that match that same VDOT at other distances. This gives realistic goal times that account for the fact that speed drops as distance grows.

Good to know

How reliable is the prediction?

A prediction is not a guarantee. It assumes you are equally well trained for every distance. A 5K runner who never does long runs is unlikely to hit their predicted marathon time — that requires specific endurance training.

Tips

From prediction to performance

Use the predicted time as a starting point for a goal and train specifically for that distance. The longer the race, the more weekly volume and the long run matter. Plan that with our personal plan.

FAQ