How running pace is worked out, step by step

The arithmetic

Total time divided by total distance

A pace chart does one job: it turns a finish time into a speed you can picture. Race results are reported as a time, but the time only makes sense once you know how long the race was. A 25-minute 5k and a 25-minute 10k are entirely different performances, and pace is the number that shows the difference. This page does the division for you, in both miles and kilometres, and then places your result next to a table of common finish times so you can see where it sits.

The arithmetic is a single division. Convert your finish time to seconds, divide by the distance in the unit you want, and turn the result back into minutes and seconds. For miles, a 5k is 3.106855 miles and a 10k is 6.21371 miles. For kilometres, a 5k is exactly 5 kilometres and a 10k is exactly 10. Worked example: a 25:00 5k is 1,500 seconds; 1,500 divided by 3.106855 is 482.8 seconds per mile, which is 8:03; 1,500 divided by 5 is 300 seconds per kilometre, which is 5:00. A 30:00 5k is 9:39 per mile and 6:00 per kilometre.

A 25:00 5k is 1,500 seconds. Divided by 3.106855 miles that is 482.8 seconds per mile, or 8:03. A 55:00 10k is 3,300 seconds. Divided by 6.21371 miles that is 531.1 seconds per mile, or 8:51. Same two steps each time.

How 5k and 10k are measured

The exact lengths, and why the units disagree

A 10k is exactly twice a 5k in metric, and exactly twice in miles as well — but a mile is not a whole number of kilometres, which is why the mile column and the kilometre column never divide into each other cleanly.

There are two ways to read a pace result, and it is worth keeping them apart. The first is the descriptive one: your average pace is a fact about a race you have already run, and it is exactly total time divided by total distance. The second is the prescriptive one: a target pace is a goal for a race you have not run yet, and it depends on your fitness, the course, and the weather on the day. This page produces the first kind of number. The reference table below gives you a sense of scale, but it does not tell you what you should be running.

Reading the chart

The reference rows, and what the boundaries mean

The reference table on the home page lists common 5k finish times from 15 minutes to an hour, with the per-mile and per-kilometre pace each one implies. Every cell in that table is recomputed from the same formula each time the site is built, so the table and the calculator cannot drift apart. Read it as a scale rather than a scoreboard: the row that matches your last race tells you your average pace, and the rows above it tell you what a faster time would require you to average.

The single most common mistake with pace numbers is to treat an average as a constant. An average pace of 8:03 per mile does not mean you ran 8:03 for every mile — it means that if you had run every mile at exactly 8:03, you would have finished at the same time. Runners almost always cover the first mile faster than the last, so an average pace sits somewhere between the pace you started at and the pace you finished at. The gap tends to widen on hilly courses and in warm conditions.

Paces are displayed as minutes and seconds, and the seconds are rounded to the nearest whole second. That matters at the boundary: 482.8 seconds is 8:03, while truncating the fraction would have printed 8:02. Rounding is also why the mile column and the kilometre column cannot both be derived from each other exactly — each is computed from your original finish time, then rounded on its own. The kilometre pace in seconds per kilometre is also reported without any rounding at all, because it is the raw number.

Sanity check

Checking a pace by hand

The second thing to watch is the unit. Metric races and imperial races produce paces in different units, and mixing them across a training week makes it hard to see whether you are actually improving. Pick one unit for your own records and convert the odd race into it rather than keeping two parallel sets of numbers. If you do convert by hand, remember that one mile is 1.609344 kilometres, so a kilometre pace multiplied by that factor gives the equivalent mile pace before rounding.