Pace Calculator
Calculate running pace, finish time, or distance across three linked modes.
Convert a measurement
Pace Calculator — your inputs
- Mode
- Find my pace
- Distance preset
- 10K (10 km)
- Distance
- 10 km
- Time (hours)
- 0 h
- Time (minutes)
- 50 min
- Time (seconds)
- 0 s
- Pace (minutes)
- 5 min
- Pace (seconds)
- 0 s
- Pace unit
- min/km
- Unit system
- Metric
Key takeaways
- Pace, time and distance are one equation with three unknowns — fix any two and the third follows.
- Race predictions across distances use Riegel's formula: time scales with distance to the power of about 1.06, not linearly.3
- That exponent is why you cannot double your 5K time for a 10K. The real penalty is about 4% per doubling.
- Training pace is not race pace. Most easy running should be 1:00–1:30 per km slower than your 5K pace.4
- Predictions assume you have trained for the distance. A well-trained 5K runner's marathon prediction is optimistic if they have never run over 15 km.
How to use this calculator
Pick a mode: find pace, finish time, or distance.
Enter the two known values; the third is calculated.
Use race presets for common distances.
Understanding your result
Pace, time, and distance are linked by pace = time ÷ distance. Change any two and the third follows.
Speed (km/h or mph) is the inverse relationship, useful for treadmill settings.
Predicting one distance from another
Runners want to know what a 5K time implies for a half marathon, and the intuitive answer — multiply by the distance ratio — is badly wrong. You cannot hold 5K pace for 21 km, and the size of that penalty turns out to be quite predictable.
Peter Riegel published the standard model in 1981 after analysing race results across distances: T₂ = T₁ × (D₂ / D₁)^1.06.3 The exponent 1.06 is the whole insight. If it were 1.0, pace would hold across any distance. At 1.06, every doubling of distance costs roughly 4% in pace — enough that a 20-minute 5K predicts about 41:40 for 10K rather than 40:00.
| Distance | Predicted time | Pace per km |
|---|---|---|
| 5 km | 20:00 | 4:00 |
| 10 km | 41:41 | 4:10 |
| Half marathon | 1:32:22 | 4:23 |
| Marathon | 3:12:33 | 4:34 |
Where the model breaks
Riegel's exponent was fitted to trained runners over a moderate range of distances. It over-predicts for anyone extrapolating far beyond their training — a fast 5K runner who has never gone past 15 km will not run the marathon time it suggests — and it does not model the specific wall the marathon presents, which is a fuelling problem as much as a fitness one.
Training paces are not race paces
The most common error in recreational running is doing every run at roughly the same moderately-hard effort. Jack Daniels' VDOT system, built from the relationship between race performance and oxygen cost, exists precisely to separate the paces out.12
| Type | Relative to 5K pace | Purpose |
|---|---|---|
| Easy (success) | +1:00 to +1:30 per km | Aerobic base, capillary and mitochondrial development. Most of your weekly volume. |
| Marathon (success) | +30 to +45 sec per km | Race-specific endurance for longer events. |
| Threshold (warning) | +15 to +25 sec per km | Raises the pace you can sustain. Roughly one-hour race effort. |
| Interval (danger) | 5K pace | VO₂ max development. 3–5 minute repeats. |
| Repetition (danger) | −10 to −15 sec per km | Speed and running economy. Short, fully recovered. |
Easy really is that much slower. Runners consistently resist this because it feels like not training, but the aerobic adaptations that make you durable — mitochondrial density, capillarisation, fat oxidation — come from time at low intensity, and running easy is what makes the hard sessions repeatable.
Pacing a race
- Go out slower than target. Positive splits — slowing in the second half — are the most common way a race goes wrong, and the damage from the first 3 km being 10 seconds per km too fast is disproportionate.
- Even or slightly negative splits. Almost every distance record has been set with the second half equal to or faster than the first.
- Adjust for the course and the weather. Hills, wind and heat all cost time. Above roughly 15 °C, expect a measurable penalty that grows with distance.
- Practise race pace in training. A pace you have never run is not a pace you can hold on the day.
- Fuel for anything over 90 minutes. Glycogen runs out. Elite marathon physiology work makes clear that even at the extreme end, carbohydrate availability is a limiting factor.5
What to do next
Set your training zones by heart rate as well as pace with the Target Heart Rate Calculator — on hills and in heat, heart rate is the more honest signal. And estimate session cost with the Calories Burned Calculator if you are managing fuelling around a plan.
Terms used on this page
- Riegel's formula
- T₂ = T₁ × (D₂/D₁)^1.06 — the standard model for predicting a race time at one distance from a result at another. The exponent encodes the pace penalty for going further.
- VDOT
- Jack Daniels' single-number expression of running fitness, derived from race performance rather than lab testing. Used to set every training pace from one race result.
- Negative split
- Running the second half of a race faster than the first. Associated with better outcomes at almost every distance, and difficult to do because it requires early restraint.
- Running economy
- The oxygen cost of running at a given pace. Two runners with identical VO₂ max can differ substantially in race performance because of it.
The formula
- 10K in 50:00 (3000 s)
- Pace = 3000 / 10 = 300 s/km = 5:00/km
- Speed = 10 / (3000/3600) = 12 km/h
Source: pace = time / distance. Published clinical/scientific formula.
Limitations
- Pace assumes even effort; real races include surges and slow-downs.
- Converts between min/km and min/mile using the exact 1.609344 factor.
References
- 1.A scoring table for running (the original VDOT tables). Daniels, J. & Gilbert, J., Oxygen Power, 1979.
- 2.Daniels' Running Formula, 4th edition. Daniels, J., Human Kinetics, 2021.
- 3.Predicting race times from training. Riegel, P.S., American Scientist 69(3):285–290, 1981.
- 4.Training intensity distribution in endurance athletes: a systematic review. Stöggl & Sperlich, Frontiers in Physiology 6:295, 2015.
- 5.Physiological demands of running at 2-hour marathon race pace. Jones et al., Journal of Applied Physiology 130(2):369–379, 2021.
Frequently asked questions
Related calculators
Calories Burned Calculator
Estimate calories burned for 20+ common activities using MET values.
Open calculatorTarget Heart Rate Calculator
Find your max heart rate and personalized training zones.
Open calculatorOne Rep Max Calculator
Estimate your one-rep max and get a full %1RM training table.
Open calculatorNot medical advice. This calculator is for general informational purposes only and is not a substitute for professional medical guidance. Always consult a qualified healthcare provider before making decisions about your health. Read the full medical disclaimer.
Printed from mystatura.com — for general information only, not medical advice.