Running Pace Calculator

Riegel's formula (1977) uses (targetDistance/yourDistance)^1.06 rather than a straight 1:1 ratio because sustainable running pace naturally slows as distance increases -- fatigue, fueling, and pacing all compound over a longer race. The extra 0.06 in the exponent is what makes doubling your race distance roughly multiply predicted time by about 2.08 instead of an unrealistic exactly-2.0, reflecting that a runner's average pace for a marathon is slower than double their 5K pace.

Riegel's formula tends to be more reliable the closer the target distance is to the distance actually run -- a 5K predicts a 10K more accurately than it predicts a marathon. Over much larger distance jumps, factors the formula doesn't model (fueling strategy, pacing discipline, and endurance limits specific to ultra-long efforts) can pull actual marathon performance further from the mathematical prediction.

Pace (minutes:seconds per mile or per kilometer) and speed (miles or kilometers per hour) describe the identical run from two different angles -- pace is time per unit distance, speed is distance per unit time, and one is mathematically the reciprocal of the other. Runners commonly think in pace ("8 minutes per mile"), while speed is more familiar from cycling or driving contexts.

Yes -- covering more distance within the same Hours/Minutes/Seconds entered directly raises the calculated Speed and correspondingly tightens (lowers) the Pace per Mile and per Kilometer, since both are derived from the same distance-over-time relationship. The reverse is also true: taking longer to cover the same distance always lowers speed and slackens pace.