Pace is finish time divided by distance. These tools answer that definition for a training run, a parkrun, or a marathon. They do not estimate fitness. If the inputs are correct, the output is the same number you would get with a stopwatch and a measured course.
Start with the general running pace calculator when the distance is not a standard race. Open the 5K, 10K, half-marathon, or marathon calculators when you have a target finish time and want pace per kilometre, pace per mile, speed, and even splits. Use the pace-to-speed converter when a watch, treadmill, or race brief mixes min/km with km/h.
Displayed times round to the nearest second. Speed rounds to one decimal place. Switch kilometres and miles in the header; the math converts, it does not guess. For hills, heart rate, or equivalent race times, leave this category and open the matching lab tool.