Training Pace Calculator
Turn one recent race into a full set of training paces. Enter the race distance (5K, 10K, half, or marathon) and your finish time (hours, minutes, seconds); get easy, tempo, and interval paces per mile or per km, plus equivalent race predictions.
Example: with Recent race 5K · Finish time — hours 0 · Minutes 25 · Seconds 0 · Show paces per mile → Easy / long run pace: 10:04 to 11:26 /mi.
- Tempo (threshold) pace8:27 /mi (about one-hour race effort)
- Interval (VO2max) pace8:03 /mi (5K race effort)
- Equivalent race timesHalf 1:55:00 · marathon 3:59:47
Computed by the calculator below using its default values. Change any input to see your own numbers.
Times scale between distances with Riegel's endurance model, t2 = t1 × (d2/d1)^1.06 (Riegel, 1981). Training paces hang off the scaled times: intervals at 5K effort, tempo at one-hour-race effort, easy runs 10-25% slower than marathon effort.
One race, every pace
Race performances scale between distances in a remarkably regular way: Pete Riegel's 1981 model says time grows with distance to the power 1.06, and it holds within a couple percent from the mile to the marathon for trained runners. That regularity means a single honest race result pins down your whole endurance curve — and your training paces are just points on it.
Intervals are run at 5K race effort, the classic VO2max stimulus. Tempo runs sit at the effort you could race for about an hour — the lactate-threshold definition used by Daniels and most modern plans — which this calculator finds by solving the Riegel curve for a 60-minute race. Easy and long runs live 10-25% slower than your marathon-equivalent pace: slow enough to recover on, fast enough to count.
Using the paces honestly
The model assumes you are trained for the distance you are predicting — a 25:00 5K runner who has never run 40-mile weeks will not see 3:59 in their first marathon. Feed it a recent, all-out result (not a workout), re-run it after each race, and let easy days drift to the slow end of the band when tired. If most of your running feels like the tempo line, you are training too hard to improve.
How it’s calculated
Equivalent times: t2 = t1 × (d2 ÷ d1)^1.06 (Riegel 1981, 'Athletic Records and Human Endurance'). Interval pace = 5K-equivalent time ÷ 5 km. Tempo pace = pace of the distance you could race in 60 minutes, from d = d1 × (60 ÷ t1)^(1/1.06). Easy band = marathon-equivalent pace × 1.10 to 1.25 (standard easy-run convention). Miles at 1 mi = 1.609344 km.
Riegel scaling assumes comparable training and conditions at both distances — heat, hills, and missing endurance base all slow real times, so treat paces as starting points and adjust by feel; consult a physician before starting hard interval training if you have cardiac risk factors.
What each pace is for
| Pace | Effort anchor | Purpose |
|---|---|---|
| Easy / long run | Marathon pace + 10-25% | Aerobic base; most weekly mileage |
| Tempo / threshold | ≈ 1-hour race effort | Raises lactate threshold; 20-40 min blocks |
| Interval / VO2max | 5K race effort | 3-5 min repeats; top-end aerobic power |
| Race predictions | Riegel ^1.06 scaling | Goal-setting and pacing plans |
Conventions consolidated from Riegel (1981) time scaling and standard threshold/VO2max training definitions (Daniels' Running Formula).
Common mistakes
- Feeding it a goal time instead of a real result — every pace inherits the fantasy.
- Running easy days at tempo pace because it feels productive; the band is slow on purpose.
- Predicting a marathon from a 5K without marathon training — the 1.06 exponent assumes you have the endurance base.
- Using track-workout bests as the input race; workouts are not races, and the model knows the difference even if you don't.
Frequently asked questions
How are training paces calculated from a race time?
Your result is scaled to other distances with Riegel's formula, t2 = t1 × (d2/d1)^1.06. Intervals then run at 5K-equivalent effort, tempo at the pace you could race for one hour, and easy runs 10-25% slower than marathon-equivalent pace. A 25:00 5K yields easy runs around 10:00-11:30 per mile.
Why is my easy pace so slow?
Because easy running builds aerobic volume with minimal fatigue — the adaptation comes from time on feet, not speed. Elite marathoners jog 60-90 seconds per mile slower than marathon pace on easy days; the band here applies the same logic to you.
What exactly is tempo pace?
The effort you could sustain in a race lasting about an hour — the standard working definition of lactate threshold. For most amateurs that lands between 10K and half-marathon pace; this calculator solves your Riegel curve for a 60-minute race to find it.
How accurate is the Riegel 1.06 model?
Within about 1-2% across common road distances for runners trained at both — good enough to set paces. It gets optimistic when the target distance is much longer than anything you have trained for, especially 5K-to-marathon jumps.
Should I use my newest race or my best race?
The most recent all-out effort at an accurately measured distance, ideally within the last couple of months. Fitness drifts; paces anchored to last year's PR train the runner you were, not the one you are.