Marathon Time Predictor Formula

Understand the math behind the marathon time predictor. Each variable explained with a worked example.

Use the Marathon Time Predictor

Formulas Used

Predicted Marathon Time (min)

marathon_time = race_time_minutes * pow(marathon_distance / race_distance, 1.06)

Marathon Time (hours)

marathon_hours = race_time_minutes * pow(marathon_distance / race_distance, 1.06) / 60

Predicted Pace

marathon_pace = race_time_minutes * pow(marathon_distance / race_distance, 1.06) / 26.2

Variables

VariableDescriptionDefault
race_time_minutesRecent Race Time(minutes)25
race_distanceRace Distance(miles)3.1
marathon_distanceDerived value= 26.2calculated

How It Works

Riegel Formula

Predicted Time = Race Time x (Target Distance / Race Distance)^1.06

The Riegel formula, developed by Peter Riegel in 1977, accounts for the fact that pace slows as distance increases. The exponent 1.06 captures this endurance fatigue factor.

Worked Example

A runner who completed a 5K (3.1 miles) in 25 minutes.

race_time_minutes = 25race_distance = 3.1
  1. 01Marathon distance = 26.2 miles
  2. 02Distance ratio = 26.2 / 3.1 = 8.452
  3. 03Predicted time = 25 x 8.452^1.06
  4. 04= 25 x 9.55 = 238.7 minutes
  5. 05= 3 hours 58.7 minutes
  6. 06Pace = 238.7 / 26.2 = 9.11 min/mile

Ready to run the numbers?

Open Marathon Time Predictor