Pace Calculator
Calculate pace, finish time, or distance — with splits, race predictions, and training zones
Enter distance or select a race preset below
Enter your target pace per kilometer or mile
Used only for calorie burn estimation
Enter Your Numbers
Fill in any two fields and the third will be calculated automatically. Use the presets for standard race distances.
How to Use the Pace Calculator
Choose What to Calculate
Select your solve mode at the top: Pace (calculate your pace from distance and time), Finish Time (calculate how long a race will take at your target pace), or Distance (calculate how far you can run in a given time at a given pace). The two input fields you fill in will determine the third automatically.
Enter Distance and Use Presets
Type any custom distance or click one of the race presets — 5K, 10K, Half Marathon, Marathon, 50K, or 100K — to fill the distance field instantly. Choose your unit system (metric or imperial) to work in kilometers or miles. The pace and results will display in your selected unit system throughout.
Review Your Split Table
Once results appear, scroll to the Split Table section. Choose your split interval (every km or every mile) and select a split strategy — Even for consistent pacing, Negative for a faster second half, or Positive for a faster first half. The table shows your target pace and cumulative time at each split point. Use the Copy Splits button to copy the table to your clipboard for printing as a race-day pacing band.
Explore Race Predictions and Training Zones
The Race Predictions section uses Riegel's formula to estimate your finish times at four standard distances based on your current pace. The Training Zones section shows target pace ranges for five workout types (Easy, Marathon, Threshold, Interval, Repetition) derived from your current fitness. The Pace Band table shows how ±5, ±10, and ±15 second pace variations affect your total finish time.
Frequently Asked Questions
What is running pace and how is it different from speed?
Running pace is the time it takes to cover one unit of distance, expressed in minutes per kilometer (min/km) or minutes per mile (min/mile). Speed is the inverse: distance covered per unit of time, expressed in kilometers per hour (km/h) or miles per hour (mph). To convert pace to speed, divide 60 by your pace in minutes: a pace of 5:00/km gives a speed of 60 ÷ 5 = 12 km/h. To convert speed to pace, divide 60 by your speed: 10 km/h gives a pace of 60 ÷ 10 = 6:00/km. Runners typically use pace because it scales directly to distance targets, making it easier to plan splits and check progress mid-race. Speed is more commonly used on treadmills and by cyclists.
How accurate is the Riegel race predictor?
Riegel's formula (T2 = T1 × (D2/D1)^1.06) is highly accurate when comparing performances at similar distances — for example, predicting a 10K time from a recent 5K performance. Accuracy decreases when predicting across very different distances, such as predicting a marathon from a mile time, because training specificity and physiology differ dramatically between short and long events. The formula also assumes equal fitness, equal training for the target distance, similar course profiles, and similar environmental conditions. Runners who are specifically trained for longer events often outperform the formula's predictions, while untrained runners attempting their first marathon may underperform. Use the predictions as planning benchmarks, not guarantees.
What is a negative split and why is it recommended?
A negative split means running the second half of a race faster than the first half. This is the opposite of what most untrained runners do — most recreational runners go out too fast, deplete glycogen early, and slow down significantly in the final miles. Negative splits work because starting conservatively preserves muscle glycogen, avoids early lactic acid accumulation, and keeps your heart rate and body temperature in a manageable zone. The physiological and biomechanical state at mile 20 of a marathon depends heavily on how controlled you were in miles 1 through 13. This calculator's negative split strategy sets the first half at 5% above your average target pace and the second half at 5% below, which is a mild differential suitable for most runners.
What do the pace zones mean?
Pace zones classify your running pace relative to the wider population of recreational and competitive runners. Elite runners (below 3:30/km or 5:38/mile) represent Olympic-level or sub-elite competitive runners. Advanced runners (3:30–4:00/km or 5:38–6:26/mile) are experienced club runners who compete seriously. Intermediate runners (4:00–5:00/km or 6:26–8:03/mile) are regular runners with consistent training and race experience. Novice runners (5:00–6:00/km or 8:03–9:39/mile) are newer to running or focusing on completing events rather than competing. Beginners (above 6:00/km or 9:39/mile) are building their base fitness. These zones provide context for your pace and a framework for setting progression goals.
How do training zones work?
Training zones are pace ranges associated with different physiological adaptations. Easy pace (approximately 25% slower than 5K pace) is used for long runs and recovery runs; it builds aerobic base and improves fat utilization without excessive stress. Marathon pace is your target race effort for the marathon event. Threshold pace (approximately 8% slower than 5K pace) is used for tempo runs of 20 to 40 minutes and improves your lactate threshold, the key predictor of distance running performance. Interval pace (approximately 5K race pace) is used for track repeats of 800m to 1600m and improves VO2 max. Repetition pace (approximately 5% faster than 5K pace) is used for short fast repeats and improves running economy and neuromuscular coordination.
How is the calorie estimate calculated?
The calorie estimate uses a simplified MET (Metabolic Equivalent of Task) approach: calories per minute = (MET × weight_kg × 3.5) / 200, multiplied by total minutes. The MET value for running varies with pace — slower running (above 6:00/km or 9:39/mile) has a MET of approximately 8, moderate running (5:00–6:00/km or 8:03–9:39/mile) uses a MET of 10, and fast running (below 5:00/km or 8:03/mile) uses a MET of 12 or higher. A rougher but commonly cited estimate is that running burns approximately 1 kcal per kilogram of body weight per kilometer, which this calculator also uses as a cross-check. Individual calorie expenditure varies based on running efficiency, body composition, terrain, and environmental conditions.