ランニングペース計算ツール
The detailed guide below is currently available in English.
Pace, speed, and how they relate
Pace is the time it takes to cover a set distance, usually quoted in minutes per mile or per kilometer; speed is the inverse, expressed in mph or km/h. This calculator converts your distance and finish time into both, so a 5K in 25 minutes is the same performance as 8:02 per mile, 5:00 per kilometer, or 7.5 mph. Runners usually train by pace because it is easy to check on a watch at any marker on the route.
How the race predictions work
The prediction table applies the Riegel formula: T2 = T1 × (D2 ÷ D1)^1.06. It assumes your performances scale with distance raised to a power just above one, which empirical studies have found holds for most trained runners. A 25-minute 5K projects to roughly 52 minutes for 10K and about four hours for a marathon. The further the predicted race is from the one you actually ran, the more the result depends on endurance training you have (or have not) done yet.
よくある質問
What is a good running pace for a beginner?
Most new runners settle somewhere between 6:00 and 7:30 per kilometer (about 9:30–12:00 per mile) for easy runs. The right pace is one at which you can still hold a conversation — speed improves naturally once running regularly.
How accurate are the Riegel predictions?
For distances between about 1,500 meters and the marathon, well-trained runners usually land within a few percent of the projection. The further the target race is from your source performance — especially a first marathon — the more the estimate can miss.
Does the calculator handle treadmill or swim paces?
Yes, the math only needs a distance and a time. Choose a custom distance in miles, kilometers, meters, or yards. Keep in mind treadmill belts and pools often measure slightly short, so calibration varies.