Ultra Predictor — Predict Ultra Marathon Times
Predict ultra marathon times for 50K, 50 mile, 100K and 100 mile from marathon or half marathon results.
Enter the known race
Distance measurement
Time in hours
Time in minutes
Time in seconds
How We Calculate This
Ultra Prediction Formula
T2 = T1 × (D2 / D1)^1.07
The exponent is increased to 1.07 for ultra distances to account for the additional fatigue factors unique to ultramarathons.
Ultra distances: 50K = 50 km, 50 miles = 80.467 km, 100K = 100 km, 100 miles = 160.934 km.
Frequently Asked Questions
Related Calculators
Marathon Time Predictor
Predict your marathon time from a shorter race result.
Half Marathon Predictor
Predict your half marathon time from 5K or 10K results.
10K Predictor
Predict your 10K time from a 5K or parkrun result.
5K Predictor
Predict your 5K time from shorter or longer race results.
Parkrun Predictor
Predict your parkrun time from other race distances.
Last updated: February 2026
All calculations are estimates. Always consult a coach or medical professional for personalised training advice.