Pace, Time and Distance
Three quantities, one relationship. Know two and the third follows:
Pace = Time ÷ Distance Time = Pace × Distance Distance = Time ÷ Pace
Pace is time per unit distance — minutes per kilometre or per mile — and lower is faster. Speed is the inverse: distance per unit time, where higher is faster. Runners think in pace because it maps directly onto what a watch shows during a race; cyclists think in speed.
Speed (km/h) = 60 ÷ pace in minutes per km
Pace per mile = pace per km × 1.609344
Pace Chart
| /km | /mile | km/h | mph | 5K | 10K | Half | Marathon |
|---|---|---|---|---|---|---|---|
| 4:00 | 6:26 | 15.00 | 9.32 | 20:00 | 40:00 | 1:24:23 | 2:48:47 |
| 4:15 | 6:50 | 14.12 | 8.77 | 21:15 | 42:30 | 1:29:40 | 2:59:20 |
| 4:30 | 7:15 | 13.33 | 8.28 | 22:30 | 45:00 | 1:34:56 | 3:09:53 |
| 4:45 | 7:39 | 12.63 | 7.85 | 23:45 | 47:30 | 1:40:13 | 3:20:26 |
| 5:00 | 8:03 | 12.00 | 7.46 | 25:00 | 50:00 | 1:45:29 | 3:30:58 |
| 5:15 | 8:27 | 11.43 | 7.10 | 26:15 | 52:30 | 1:50:46 | 3:41:31 |
| 5:30 | 8:51 | 10.91 | 6.78 | 27:30 | 55:00 | 1:56:02 | 3:52:04 |
| 5:45 | 9:15 | 10.43 | 6.48 | 28:45 | 57:30 | 2:01:19 | 4:02:37 |
| 6:00 | 9:39 | 10.00 | 6.21 | 30:00 | 1:00:00 | 2:06:35 | 4:13:10 |
| 6:15 | 10:04 | 9.60 | 5.97 | 31:15 | 1:02:30 | 2:11:52 | 4:23:43 |
| 6:30 | 10:28 | 9.23 | 5.74 | 32:30 | 1:05:00 | 2:17:08 | 4:34:16 |
| 6:45 | 10:52 | 8.89 | 5.52 | 33:45 | 1:07:30 | 2:22:24 | 4:44:49 |
| 7:00 | 11:16 | 8.57 | 5.33 | 35:00 | 1:10:00 | 2:27:41 | 4:55:22 |
| 7:15 | 11:40 | 8.28 | 5.14 | 36:15 | 1:12:30 | 2:32:57 | 5:05:55 |
| 7:30 | 12:04 | 8.00 | 4.97 | 37:30 | 1:15:00 | 2:38:14 | 5:16:28 |
| 7:45 | 12:28 | 7.74 | 4.81 | 38:45 | 1:17:30 | 2:43:30 | 5:27:01 |
| 8:00 | 12:52 | 7.50 | 4.66 | 40:00 | 1:20:00 | 2:48:47 | 5:37:34 |
Predicting Times at Other Distances
Peter Riegel's 1977 formula converts a known race result into a predicted time at another distance:
T2 = T1 × (D2 ÷ D1)1.06
The exponent 1.06 encodes the fact that pace slows as distance grows — doubling the distance takes slightly more than twice the time. It works well between distances within a factor of about four, and is known to be optimistic when extrapolating from a 5K to a marathon, where endurance and fuelling matter far more than the formula can capture.
Race Distances
| Race | Kilometres | Miles |
|---|---|---|
| 1 mile | 1.609 | 1 |
| 5K | 5 | 3.107 |
| 10K | 10 | 6.214 |
| 10 miles | 16.093 | 10 |
| Half marathon | 21.0975 | 13.109 |
| Marathon | 42.195 | 26.219 |
| 50K ultra | 50 | 31.069 |
| 100K ultra | 100 | 62.137 |
The marathon's peculiar 42.195 km comes from the 1908 London Olympics, where the course was extended so the race could start at Windsor Castle and finish in front of the royal box.
Even, Negative and Positive Splits
| Strategy | What it means | Usually best for |
|---|---|---|
| Even splits | The same pace throughout | Most runners, most distances |
| Negative splits | The second half faster than the first | Marathons and half marathons |
| Positive splits | Starting fast and slowing | Almost never intentional |
Nearly every distance world record has been set with even or slightly negative splits. Starting too fast depletes glycogen and accumulates fatigue that cannot be recovered mid-race — the standard advice is to run the first few kilometres feeling slightly too slow.
Training Pace Zones
Expressed relative to current 5K race pace:
| Zone | Pace relative to 5K | Purpose |
|---|---|---|
| Easy / recovery | 1:30–2:30 per km slower | Aerobic base; the bulk of weekly mileage |
| Marathon pace | 0:30–1:00 slower | Race-specific endurance |
| Threshold / tempo | 0:15–0:30 slower | Raising the lactate threshold |
| Interval / VO2max | 5K pace to slightly faster | Maximal aerobic capacity |
| Repetition | Considerably faster | Speed and running economy |
The widely used 80/20 principle holds that roughly 80% of training volume should sit in the easy zone. The most common error among recreational runners is running easy days too hard, which accumulates fatigue without the adaptation that either easy or hard training provides.
What Slows You Down
- Hills. Roughly 12–15 seconds per kilometre lost per 1% of gradient uphill, and only about half of that regained on the way down.
- Heat. Above about 15°C, marathon performance falls by around 1–2% for every 5°C, and humidity compounds it.
- Wind. A headwind costs far more than an equivalent tailwind returns.
- Altitude. Above roughly 1,500 m, endurance performance declines measurably without acclimatisation.
- Surface. Trail and sand are substantially slower than road or track.
Frequently Asked Questions
What is a good pace?
Entirely relative to experience, age and goals. A common recreational benchmark is a 5K around 25–30 minutes (5:00–6:00 per km) and a marathon around 4 to 4:30. Improvement against your own previous times is the only comparison that matters.
How do I convert between min/km and min/mile?
Multiply min/km by 1.609 for min/mile, or divide by 1.609 to go the other way. A 5:00/km pace is about 8:03/mile.
Why is my GPS distance different from the official course?
Courses are measured along the shortest legal route. GPS drift and running wide on corners typically add 1–2%, which on a marathon is 400–800 metres — enough to make your watch's pace look faster than your official one.
Does the predictor work for ultramarathons?
Poorly. Beyond the marathon, terrain, fuelling, sleep and pacing dominate, and Riegel's formula was never fitted to those distances.