Race predictions assume training for the target distance; marathon times predicted from short races are usually optimistic.
Covering 10 km in 50:00 is a pace of 5:00 per km (8:03 per mile), 12 km/h. The same effort predicts about 3:50:00 for a marathon.
Riegel race predictions
Equal-effort pace by distance
Even splits per km Righe: 10
Split
Distance (km)
Split time
Elapsed
1
1
5 min
5 min
2
2
5 min
10 min
3
3
5 min
15 min
4
4
5 min
20 min
5
5
5 min
25 min
6
6
5 min
30 min
7
7
5 min
35 min
8
8
5 min
40 min
9
9
5 min
45 min
10
10
5 min
50 min
Come si calcola S
Pace per km
10km3,000s=300.00s=5:00
Velocità
0.833333h10km=12.00km/h
Riegel prediction (marathon)
3,000.0×(10,00042195)1.06=13,800.6s=3:50:00
Times are shown truncated to the second.
Informazioni su Running pace calculator
Pace is finish time divided by distance, shown per kilometre and per mile; enter two of distance, time and pace (or speed) to get the third. Race predictions use Peter Riegel's 1981 formula, T₂ = T₁ × (D₂ ÷ D₁)^1.06, which scales one result to the 5K, 10K, half marathon and marathon. Even splits are listed per kilometre or mile.
Runners use it to plan race pacing and training targets. The default 10 km in 50:00 is 5:00 per km, 8:03 per mile or 12 km/h, and Riegel's formula turns it into a 23:58 5K, a 1:50:19 half marathon and a 3:50:00 marathon.
Riegel predictions assume equal preparation for each distance. In a study of 2,303 recreational runners, Vickers and Vertosick (2016) found the formula well calibrated up to the half marathon but at least 10 minutes too fast at the marathon for half of them.
Esempi svolti
Marathon in 3:30:00
Solve for
Pace
Distance
42.195 km
Finish time
3:30:00
Pace and splits per
Kilometre
Pace per km
4 min 58 s
Pace per mile
8 min
Velocità
12.06 km/h
Fonte di verifica: Python 3.8 decimal: 12600 s ÷ 42.195 km; 12600 ÷ (42195/1609.344) mi; 42.195 ÷ 3.5 h
5K at 8:00 per mile
Solve for
Finish time
Distance
5 km
Pace and splits per
Mile
I know my
Pace
Pace
8:00
Finish time
24 min 51 s
Pace per km
4 min 58 s
Fonte di verifica: Python 3.8 decimal: 480 s × 5000/1609.344 = 1491.2909 s
Distance from 1:45:00 at 5:00 per km
Solve for
Distance
Finish time
1:45:00
Pace and splits per
Kilometre
I know my
Pace
Pace
5:00
Distance
21 km
Distance in miles
13.049 mi
Fonte di verifica: Python 3.8 decimal: 6300 s ÷ 300 s/km = 21 km = 13.04880 mi
Riegel predictions from 10 km in 50:00
Solve for
Pace
Distance
10 km
Finish time
50:00
Pace and splits per
Kilometre
Predicted 5K
23 min 58 s
Predicted 10K
50 min
Predicted half marathon
1 h 50 min 19 s
Predicted marathon
3 h 50 min
Fonte di verifica: Python 3.8 decimal: 3000 × (D₂/10000)^1.06 for 5000, 21097.5 and 42195 m
Domande
How do you calculate running pace?
Divide finish time by distance. A 10 km run in 50 minutes is 50 ÷ 10 = 5:00 per km; the same run is 6.214 miles, so the pace is 8:03 per mile. Speed is the inverse: 60 ÷ 5 = 12 km/h. One mile is exactly 1.609344 km (NIST SP 811), the factor used to switch between per-kilometre and per-mile pace.
What pace do you need for a sub-4-hour marathon?
Faster than 5:41 per km, or 9:09 per mile, held for all 42.195 km: 14,400 s ÷ 42.195 km = 341.3 s per km. A sub-2-hour half marathon needs exactly the same pace, because 21.0975 km is half the marathon distance. Any time lost at aid stations or on a slow start has to be made up with faster running later.
Are Riegel race time predictions reliable?
Up to the half marathon, mostly. Vickers and Vertosick's 2016 study of 2,303 recreational runners found Riegel's formula well calibrated to that distance but too optimistic for the marathon, giving times at least 10 minutes too fast for half the runners. Their own models, which used training data and prior races, cut the marathon prediction error by about 40 %. Riegel fitted his 1.06 exponent to world-record performances.
How long is a marathon and a half marathon?
A marathon is 42.195 km (26.219 miles) and a half marathon is 21.0975 km (13.109 miles), the standard road distances in World Athletics rules. At an even 5:00 per km they take about 3 h 31 min and 1 h 45 min. Use the distance presets to fill in these exact values.
Quanto è preciso «Running pace calculator»?
La precisione dipende dai dati inseriti e dalle ipotesi del metodo. Il calcolo decimale usa 50 cifre significative, ma stime, metodi numerici e dati di origine possono essere meno precisi; l’arrotondamento visualizzato non elimina questi limiti. Esempi svolti verificati con fonti indipendenti: 6. Per esempio, «Marathon in 3:30:00» viene verificato con Python 3.8 decimal: 12600 s ÷ 42.195 km; 12600 ÷ (42195/1609.344) mi; 42.195 ÷ 3.5 h.
Da dove proviene il metodo?
Riegel PS. Athletic records and human endurance. American Scientist 1981;69(3):285–290; World Athletics Competition Rules — standard road distances: half marathon 21.0975 km, marathon 42.195 km; NIST SP 811 — 1 mile = 1609.344 m exactly.