Your pace
5:00
min/km
Speed
12.00
km/h
Pace per mile
8:03
the same effort in min/mi
Race times at this pace
Assumes you hold this exact pace the whole way. Most runners slow as the distance grows, so read the longer races as an optimistic ceiling rather than a target.
Total time
50:00
for 10 km
Time per 400m lap
2:00
one lap of a running track
How the Pace Calculator Works
One formula, three questions
Everything here comes from pace = time ÷ distance, rearranged. Give it distance and time and it returns pace; distance and pace and it returns your finish time; time and pace and it returns how far you went. Pick what you want to calculate and fill in the other two.
Pace and speed are the same thing
Pace is time per unit of distance; speed is distance per unit of time. They are reciprocals, so 5:00 min/km is exactly 12 km/h. Runners tend to think in pace because it translates straight into a race plan — you can watch it on a watch and know instantly whether you are on target. Cyclists tend to think in speed.
Converting between km and miles
A mile is about 1.609 km, so a 5:00 min/km pace is roughly 8:03 min/mile. Watch the direction: because a mile is longer, the pace per mile is the bigger number — the opposite of what happens when you convert the distances themselves. Switching units above converts your entries rather than reinterpreting them, so the run stays the same.
About the race projections
The race table assumes you hold exactly the same pace over every distance, which is optimistic. In reality pace drifts as distance grows — a marathon projected from your 5K pace is a ceiling, not a plan. Experienced runners typically add a meaningful margin per step up in distance.
Frequently asked questions
How do I calculate running pace?
Divide your time by the distance: pace = time ÷ distance. A 50-minute 10K is 50 ÷ 10 = 5 minutes per kilometre. Pace and speed are two views of the same thing — pace is time per unit of distance, speed is distance per unit of time, so one is the reciprocal of the other.
What is the difference between pace and speed?
Pace answers 'how long does each kilometre take?' and speed answers 'how far do I go each hour?'. Runners generally think in pace because it maps directly onto a race plan, while cyclists think in speed. A pace of 5:00 min/km is a speed of 12 km/h — the same effort described two ways.
How do I convert pace per kilometre to pace per mile?
Multiply by 1.609, since a mile is that many kilometres. A 5:00 min/km pace is about 8:03 min/mile. Note the direction: because a mile is longer, the pace per mile is always the larger number, which is the opposite of what happens when converting the distances themselves.
What is a good running pace?
It depends entirely on experience, distance and goals. Many recreational runners sit somewhere around 6:00-7:00 min/km for an easy run, while a sub-3-hour marathon needs roughly 4:15 min/km sustained for 42 km. The more useful comparison is with your own previous times rather than anyone else's.
Can I predict a race time from my current pace?
The projections here assume you hold exactly the same pace across the distance, which is optimistic for longer races — most runners slow down as distance increases. Treat a marathon projection from a 5K pace as an upper bound rather than a realistic target, and expect to add time as the distance grows.
Why do I need to leave a field blank?
The calculator solves for whatever is missing, so it needs exactly two of distance, time and pace. Filling in all three would over-determine the problem and the values would usually contradict each other. Clear the one you want to work out and it will be calculated from the other two.