Half Marathon Pace Calculator
Whether you are targeting a specific half marathon time or wondering what your 5K or 10K fitness translates to over 13.1 miles, this calculator has you covered. Get your required pace and 5K split times to help you pace evenly on race day.
The half marathon (21.0975 km / 13.1 miles) has become the fastest-growing race distance in the world. It demands real endurance training but does not require the months-long buildup of a full marathon, making it an attractive goal for intermediate runners.
Finish times span a wide range. Elite runners complete a half marathon in under 60 minutes, experienced club runners target 1:30 to 1:50, and recreational runners typically finish between 2:00 and 2:30. Your ideal pace depends on your current fitness, training volume, and race experience.
The predictions from shorter race times use the Riegel formula (T2 = T1 x (D2/D1)^1.06), which accounts for the natural pace slowdown as distance increases. Predicting from a 10K is more accurate than from a 5K because the 10K is closer in distance and demands similar aerobic capacity. The formula assumes both races were run at full effort on comparable courses.
Race day pacing is critical for the half marathon. Going out too fast in the first 5K is the most common mistake and leads to a painful final 5K. A conservative approach -- running the first 5K at target pace or slightly slower, settling into rhythm for the middle 10K, and pushing the final 5K if you have energy left -- produces the most consistent results. Use the split times to check yourself at each 5K marker.