Running Pace Calculator (pace, speed, time)

Understanding the running pace calculator — concept and principle

Pace tells you how long it takes to cover one kilometre or one mile; speed tells you how far you travel in one hour. Runners think in pace because it maps directly onto a watch and onto race plans, while treadmills and cyclists usually show speed. Enter a distance and a finishing time, and this calculator gives your pace per km and per mile plus your speed in km/h and mph.

How it is calculated

First the time is turned into minutes: t = hours × 60 + minutes + seconds ÷ 60.

• Pace per km = t ÷ distance (km), shown as minutes:seconds.
• Pace per mile = pace per km × 1.609344, because one international mile is exactly 1,609.344 m.
• Speed (km/h) = distance ÷ (t ÷ 60).
• Speed (mph) = speed (km/h) ÷ 1.609344.

Pace is shown rounded to the nearest second.

The principle

Pace and speed are reciprocals of each other: pace = 60 ÷ speed when pace is in minutes per km and speed in km/h. Both describe an average, assuming you covered the whole distance at an even rate. Reciprocal relationships are not linear, which is why a pace change of 10 seconds per km matters more at fast speeds than at slow ones in terms of km/h, and why averaging two paces is not the same as averaging two speeds.

Worked example

1. Time: 0 × 60 + 50 + 0 ÷ 60 = 50 minutes.
2. Pace per km: 50 ÷ 10 = 5.000 min = 5:00 /km.
3. Pace per mile: 5 × 1.609344 = 8.0467 min, rounded to 8:03 /mile.
4. Speed: 10 ÷ (50 ÷ 60) = 12 km/h, and 12 ÷ 1.609344 = 7.46 mph.

How to read the result

A 5:00 /km pace is a solid recreational effort; many beginners run easy kilometres at 6:30 to 7:30, while elite marathoners hold under 3:00. Use the pace to plan races: a 10 km at 5:00 /km means passing each km marker every five minutes. Compare against your training paces, not other people's: easy runs are usually well slower than race pace, and hills, heat and wind all slow pace at the same effort.

Common mistakes

• Entering 1.5 hours as 1 hour 50 minutes; use hours 1 and minutes 30.
• Treating 8.05 min/mile as 8:05; 0.05 min is 3 seconds, so it is 8:03.
• Trusting GPS distance blindly; watches often read a few percent long or short.
• Averaging lap paces instead of dividing total time by total distance.

Frequently asked questions

What is the difference between pace and speed?

Pace is time per distance (min/km), speed is distance per time (km/h). Pace = 60 ÷ speed.

What pace do I need for a sub-2-hour half marathon?

The half marathon is 21.0975 km, so 120 ÷ 21.0975 = 5.688 min, or about 5:41 per km.

Why does my treadmill pace feel easier than outside?

There is no air resistance and the belt helps leg turnover, so many runners set a 1% incline to come closer to outdoor effort.

Sources: International Yard and Pound Agreement (1959), defining 1 yard = 0.9144 m, so 1 mile = 1,609.344 m.