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Calculators / Sports / Race time predictor
Race time predictor calculator
Project an endurance race time from a completed distance and time.
On this page
Predicted target time52.12minutes
Predicted average pace5.21min/km
Calculator controls
How to calculate
Project an endurance race time from a completed distance and time.
target time = known time × (target distance ÷ known distance)^fatigue exponent
Worked example
Completed distance (km): 5; Completed time (minutes): 25; Target distance (km): 10; Fatigue exponent: 1.06.
Predicted target time: 52.12 minutes; Predicted average pace: 5.21 min/km.
Assumptions and limits
Training, terrain, weather, pacing, distance difference, and individual endurance make this a planning estimate, not a guarantee.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Project an endurance race time from a completed distance and time. Every assumption remains visible so the result can be checked or changed.
When this tool is useful
Use the race time predictor for an initial estimate, comparison, or classroom calculation.
Understanding your inputs
| Input | What to enter |
|---|---|
| Completed distance (km) | Enter a number of at least 0.000001 and no more than 1000000000000. |
| Completed time (minutes) | Enter a number of at least 0.000001 and no more than 1000000000000. |
| Target distance (km) | Enter a number of at least 0.000001 and no more than 1000000000000. |
| Fatigue exponent | Enter a number of at least 0.5 and no more than 2. |
Frequently asked questions
What are the limits of this race time predictor?
Training, terrain, weather, pacing, distance difference, and individual endurance make this a planning estimate, not a guarantee.
Can I use different units?
Use the units printed beside each field. Convert measurements first when your source uses different units.