Pace: the runner's most useful number
Pace expresses how fast you're moving as time per unit distance — minutes per kilometre or per mile — which is generally more intuitive for runners than speed (distance per unit time), since it maps directly onto how training plans, race splits, and personal bests are usually discussed and tracked.
This calculator converts between the two: enter any distance and the time it took, and it works out your pace per kilometre, pace per mile, and equivalent speed in kilometres per hour — useful whether you're checking a recent run, planning splits for an upcoming race, or converting between metric and imperial training plans.
Using pace to plan training
Many structured training plans prescribe specific paces for different session types — easy runs at a conversational pace, tempo runs at a "comfortably hard" pace, and interval work at a much faster pace relative to current fitness. Knowing your current pace across different distances and efforts is the starting point for following any pace-based training plan accurately.
From pace to race prediction
A known pace at one distance can help estimate performance at another, though the relationship isn't perfectly linear — pace naturally slows somewhat as distance increases due to fatigue and pacing strategy. The Running Calculator on this site uses the Riegel formula to make that longer-distance prediction more accurately than a simple linear scaling would.