Running Pace Calculator
Training for a race or just tracking your runs? Calculate your pace from time and distance, predict your finish time, or work out how far you can run at a given pace. Also shows predicted race times for 5K, 10K, half marathon, and full marathon.
How to use
- Pick what you're solving for: pace, finish time, or distance.
- Fill in the values you already know.
- Your result and race predictions show up right away.
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Running pace, time, and distance form a simple triangle: know any two and you can calculate the third. If you ran 10km in 55 minutes, your pace was 5:30 per km. If you want to run a half marathon (21.1km) at that same pace, your finish time would be around 1 hour 56 minutes. The calculator handles all three directions.
Race time predictions use Riegel formula: T2 = T1 x (D2/D1)^1.06. It accounts for the fact that pace slows over longer distances - you cannot maintain 5K pace for a marathon. The exponent 1.06 is based on observed race data and tends to be fairly accurate for trained runners. Beginners often slow more than predicted; elite runners closer to the prediction.
Frequently Asked Questions
What is a good running pace for beginners?
Comfort varies widely. Many beginners run at 7-9 minutes per km. The more useful measure is whether you can hold a conversation while running (the talk test). If you cannot speak a sentence without gasping, slow down - most easy runs should feel genuinely easy.
What is negative splitting and why is it recommended?
Running the second half of a race faster than the first. It conserves glycogen, avoids early lactate buildup, and psychologically feels better than dying in the last km. Most runners start too fast - negative splitting is a discipline that improves finish times.
How accurate are race time predictions?
Reasonably accurate for runners with consistent training within a similar distance range. The prediction breaks down if you are jumping from a 5K to a marathon without mileage base. Training specificity matters more than the formula at extreme distance jumps.