Estimate your half marathon time with science based formulas using your latest race or custom test. Compare Riegel and Daniels predictions. Adjust for course hilliness weather and training level. View split by kilometer and mile pacing plus hydration alerts and race strategy tips for a smart confident run including warmup suggestions and taper reminders
Riegel and Daniels methods are widely used but individual results vary based on training specificity conditions and pacing. Use the band as a realistic range rather than a guarantee.
Races near the half marathon such as 15K to 20K are ideal. 5K and 10K can work if your endurance training is strong.
1.06 is a common default. Faster endurance athletes may see a lower value while newer runners might see higher values. You can tune it with your own results.
Warmer conditions and hills typically slow finishing times. This tool adds a small percent adjustment for each factor to refine the estimate.
VDOT is a performance metric popularized by Jack Daniels relating running economy intensity and fitness. Matching VDOT across distances predicts equivalent performances.
Yes. Use the blended pace as a starting point and adjust based on recent long run pace nutrition strategy and course profile.
No. It predicts race time and pace. For a plan consider weekly mileage long runs tempo and intervals progressing gradually to avoid injury.
Use the manual adjustment field. A negative value can reflect good taper while a positive value can reflect heavy legs or partial recovery.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.