Forecast marathon, half, and 10K goals, then export the plan youβll actually execute.
Input one recent finish time to project new goals, apply weather and elevation adjustments, generate pacing charts, and estimate fueling needs. The calculator keeps your stretch time ambitious yet achievable.
π Race prediction & goal pace
Predict a target race or lock in a manual goal time to see required pace, splits, and fueling guidance instantly.
Recent result
Target race
Predicted/goal finish
β
Required average pace
β min/km
Tip
Use 1.03β1.04 for aggressive pacing, 1.06 default, and 1.07β1.08 for conservative endurance-focused attempts.
Split chart
Weather adjustment
Fuel & hydration
Training pace guide
- β’ Easy: β /km (β /mile)
- β’ Marathon pace: β /km (β /mile)
- β’ Tempo (half): β /km (β /mile)
- β’ Threshold (10K): β /km (β /mile)
- β’ Intervals (5K): β /km (β /mile)
Weekly 80/20 planner
Interval session planner
Frequently Asked Questions
These answers match the structured FAQ data on this page.
How accurate is the race time predictor?
It provides a strong baseline from your recent result using the Riegel model. Accuracy improves when your target race and training conditions are similar.
Can I predict marathon pace from a 10K result?
Yes. The tool extrapolates across distances and then lets you adjust for weather, altitude, and pacing strategy.
Should I still run by heart rate?
Yes. Use predicted pace as a target and cross-check with heart-rate zones, especially in heat, wind, and long races.
Last updated: February 25, 2026