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Marathon Time Calculator: Predict Your Marathon Race Time

Welcome to our advanced marathon race time calculator!

Simply enter how fast you’ve run one or two previous races and how much you’ve been training approximately per week, and this calculator will predict how fast you’d run a marathon.

Unlike most race time prediction tools which tend to become inaccurate when predicting distances greater than a half marathon, this marathon time calculator uses an advanced set of formulas developed specifically for predicting marathon race time for non-professional runners.

The formulas used in this marathon time calculator were developed by Andrew J. Vickers and Emily A. Vertosick at Slate.

For predicting a wider range of race distances, check out our classic race time predictor and our age-grade calculator.

Marathon Race Time Prediction Calculator


Previous Race 1

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Previous Race 2 (Optional)

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Looking to convert your race time goal into a pace target?

Then head to our Running Pace Calculator.

How Does The Calculator Work?

Limitations of Traditional Prediction Methods

One big issue with the traditional race time prediction formulas, such as the Riegel formula, Cameron formula, and age-graded method, is that they tend to be based on the race times of professional runners, meaning they are often inaccurate when used to predict race times of recreational distance runners, especially when predicting marathon times.

For example, as of 2023 the world record time for the half marathon is 57:31, and the world record for the marathon is 2:01:09, meaning that both races are run at a similar pace.

Yet, the average runner, who hasn’t had access to professional training, is more likely to run a marathon at a notably slower pace than a half marathon.

Therefore, a formula developed from the race times of professional runners isn’t going to be particularly useful for predicting the marathon distance for the average runner, and formulas such as the Riegel formula tend to underpredict race times beyond the half marathon distance by ten minutes or more.

Some data even suggests that only 5% of runners may actually beat the prediction given by the Reigel formula when predicting a marathon finish time based on a half marathon time.

This is an issue if recreational runners formulate their training goals and pace targets from said inaccurate predictions, resulting in potential overtraining, missed goals, and race-day disappointment.

This is where the more advanced marathon race time prediction method steps in.

The Vickers-Vertosick Method

Vickers and Vertosick used data from over 2000 recreational runners to determine how best to predict endurance running performance based on training and runner characteristics. It is unique in the fact that it focused on non-professional runners, whereas past studies tended to focus on elite runners.

They found that weekly training mileage was strongly associated with race time, and by incorporating this as a predictor, they were able to develop a set of equations for predicting race time significantly more accurately than the classic Riegel formula, particularly for longer distances.

The equations developed by Vickers and Vertosick are the equations that are used in the above marathon time calculator.

Other Factors Affecting Marathon Race Time

No prediction calculator can be 100% accurate, so it’s important to consider that any of the following factors can also affect your race time: