Running Pace Calculator

Pace measures the time it takes to cover a unit of distance (minutes per kilometer or minutes per mile). Speed measures the distance covered per unit of time (kilometers per hour or miles per hour). They are inversely related: a faster runner has a lower pace number but a higher speed number. Runners typically think in terms of pace because it directly translates to split times during a race. A 5:00 min/km pace means each kilometer takes exactly 5 minutes, making it easy to track progress at distance markers.

The Riegel formula, published by Peter Riegel in 1977, predicts race times at different distances using T2 = T1 times (D2/D1) raised to the power of 1.06. T1 is your known time, D1 is the known distance, D2 is the target distance, and T2 is the predicted time. The exponent 1.06 accounts for fatigue: as distance increases, pace slows slightly. For example, if you run 10K in 50 minutes, the formula predicts a half marathon time of about 1:50:23. It works best for distances between 1500m and the marathon.

A negative split means running the second half of a race faster than the first half. For example, in a marathon, you might run the first half in 1:55 and the second half in 1:50. This pacing strategy prevents starting too fast and hitting the wall later. Most world records in distance events were set with negative or even splits. A common approach is to run the first half 2-5% slower than goal pace, then gradually increase speed. The splits calculator in this tool lets you plan negative split pacing for any distance.

Training zones define different intensity levels based on your race pace. Easy pace (typically 65-75% effort) is for recovery and base building. Tempo pace (about 85-90% effort) improves lactate threshold. Threshold pace (88-92%) is the fastest pace you can sustain for about an hour. Interval pace (95-100%) builds VO2max through repeated hard efforts with rest. Repetition pace (faster than race pace) develops running economy and speed. This calculator shows your training zones based on your current pace or race result.