Running Pace, Speed & Time Calculator

Mastering Running Pace, Speed & Finish Times

Pace is the foundational metric for runners, representing the time required to complete a specific unit of distance (minutes per kilometer or minutes per mile). Converting between speed (km/h or mph) and pace allows runners to structure treadmill workouts and race day pacing strategies.

5 Calculation Modes

• Find Pace: Calculate min/km or min/mile given total distance and duration.
• Find Time: Calculate total race finish time given target pace and distance.
• Speed & Pace Converter: Convert treadmill speed (km/h) to equivalent running pace (min/km).
• Find Distance: Calculate total distance run given average pace and workout duration.
• Race Time Predictor: Predict 5K, 10K, Half Marathon, and Full Marathon finish times using Riegel's formula.

Riegel's Fatigue Formula for Race Prediction

Peter Riegel's empirical formula accounts for aerobic fatigue accumulation as race distance increases. An exponent of 1.06 models the expected slowdown over longer endurance distances.

Worked Examples

• Pace Calculation: Running 10 km in 50 minutes → Pace = 50 / 10 = 5:00 min/km (Speed = 12 km/h).
• Race Prediction: A 5K time of 24:00 predicts a Half Marathon time of ~1:51:30 and a Full Marathon time of ~3:52:15.