Running pace calculator

Running pace per km or mile from distance and time, or finish time or distance from pace, with even splits and Riegel race predictions.

更新日 2026年9月28日検証済みの例：6

Pace per km

5 minper km

Pace per mile: 8 min 2 sper mile
Finish time: 50 min
Distance: 10km
Distance in miles: 6.214mi
速さ: 12.00km/h
Speed in miles per hour: 7.46mph
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

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 行数：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

計算方法 S

Pace per km
$\frac{3{,}000\ \text{s}}{10\ \text{km}} = 300.00\ \text{s} = 5:00$
速さ
$\frac{10\ \text{km}}{0.833333\ \text{h}} = 12.00\ \text{km/h}$
Riegel prediction (marathon)
$3{,}000.0 \times \left(\frac{42195}{10{,}000}\right)^{1.06} = 13{,}800.6\ \text{s} = 3:50:00$
Times are shown truncated to the second.

Running pace calculatorについて

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.

計算例

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
速さ: 12.06 km/h

照合元：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

照合元：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

照合元：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

照合元：Python 3.8 decimal: 3000 × (D₂/10000)^1.06 for 5000, 21097.5 and 42195 m

よくある質問

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.

「Running pace calculator」の精度はどのくらいですか？

精度は入力値と計算方法の前提に依存します。十進演算には有効数字50桁を使いますが、推定、数値計算手法、元データの精度はそれより低い場合があります。表示の丸め処理でこれらの制約がなくなるわけではありません。独立した出典の解答と照合した計算例：6。例えば、「Marathon in 3:30:00」はPython 3.8 decimal: 12600 s ÷ 42.195 km; 12600 ÷ (42195/1609.344) mi; 42.195 ÷ 3.5 hと照合しています。

この計算方法の出典は何ですか？

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.

この計算機について

\text{pace} = \frac{t}{d},\qquad T_2 = T_1\left(\frac{D_2}{D_1}\right)^{1.06}

出典

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

出典と照合済み

この計算機には、独立した出典の解答を使った計算例が 6 件あります。テストに組み込まれており、ここでも実行できます。