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Running Pace Calculator
Calculate running pace, finish time, or distance. Includes training zones (easy, tempo, threshold, interval) and race predictions.
HEALTHCalculate your running pace, finish time, or distance. Includes training pace zones (easy, long run, marathon, threshold, intervals) and race-time predictions for 5K, 10K, half marathon, and marathon from one known result.
Pace = total time divided by total distance. Race predictions use Riegel's formula: T2 = T1 × (D2/D1)^1.06. Training paces derive from race pace: easy is +60-90 sec/mi slower than 5K, marathon pace is +60-75 sec/mi, threshold is +25-30 sec/mi, VO2max intervals are at 5K pace. 80% of weekly mileage should be easy; only 20% at threshold or harder.
Disclaimer: Pace predictions assume similar effort levels and trained runners. Race-day weather, course profile, and fitness specificity (5K speed vs marathon endurance) shift actual times.
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Frequently Asked Questions
How do I calculate my running pace?
Pace = total time / total distance. If you run a 5K in 25:00, your pace is 25:00 ÷ 3.1 mi = 8:04/mi (or 5:00/km). The calculator handles three modes: pace from time + distance, time from pace + distance, and distance from pace + time - so you can solve for whichever variable you do not know.
What pace should I run my easy runs at?
Easy runs should be 60-90 seconds per mile slower than your 5K race pace. If you run an 8:00/mi 5K, easy runs are around 9:00-9:30/mi. The talk test is the practical version: you should be able to hold a conversation. About 80% of weekly mileage should be at this easy pace; only 20% at threshold or harder.
How do I predict my marathon time from my 5K?
Use Riegel's formula: T2 = T1 × (D2/D1)^1.06. A 25:00 5K predicts roughly 3:51:00 for the marathon (25 × (26.2/3.1)^1.06). Note this assumes equal marathon-specific training - if you have not done the long runs and tempo work, the actual time will be 10-20 minutes slower. The 1.06 exponent reflects that longer races require pace decay.
What is a good marathon time?
Highly subjective. US median marathon finish is around 4:30 (men) and 4:50 (women). Boston Marathon qualifying times for 18-34 year old men: 3:00; for women: 3:30. Sub-4:00 marathon is achievable for most healthy adults with 16-20 weeks of structured training. Sub-3:00 takes serious dedication and 60+ miles per week.
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