20K pace and finish time calculator

The 20K is 20000 metres — 20.00 km, or 12.427 miles. Enter a pace and this gives the finish time, or work backwards from a target.

Finish time
1:52:00
= Exact 20K pace
Speed
10.714
Pace per mile
9:01
Pace per kilometre
5:36
Pace needed for the target time
0:00
Halfway split
0:56:00
Quarter split
0:28:00
Pace per 400 m lap
2:14
Track laps
50.00
Speed in metres per second
2.976
Show the working
  1. Pace, minutes per km = 5.6
  2. Plus seconds = 0
  3. Or a target time, hours = 0
  4. Target minutes = 0
  5. distance_m = 20000 = 20 000
  6. distance_km = 20 000 / 1000 = 20
  7. Pace per kilometre = 5.6 * 60 + 0 = 336
  8. Finish time = 336 * 20 = 6720
  9. Speed = 336 > 0 ? 3600 / 336 : 0 = 10.7143
  10. Speed in metres per second = 10.7143 / 3.6 = 2.976 19
  11. Pace per mile = 336 * 1.609344 = 540.74
  12. target_seconds = 0 * 3600 + 0 * 60 = 0
  13. Pace needed for the target time = 20 > 0 && 0 > 0 ? 0 / 20 : 0 = 0
  14. Halfway split = 6720 / 2 = 3360
  15. Quarter split = 6720 / 4 = 1680
  16. Pace per 400 m lap = 336 * 0.4 = 134.4
  17. Track laps = 20 000 / 400 = 50

Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.

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    The formula

    • finish time = pace per km x distance in km
    • pace per mile = pace per km x 1.609344
    • speed in km/h = 3600 / pace in seconds per km

    Splits assume an even pace. Most runners are better served by starting slightly slower than target and finishing faster.

    The mile is exactly 1609.344 m, so the pace conversion here is exact rather than rounded.

    Finish times for the 20K

    Pace per km Pace per mile Finish time
    3:30 5:381:10:00
    4:00 6:261:20:00
    4:30 7:151:30:00
    5:00 8:031:40:00
    5:30 8:511:50:00
    6:00 9:392:00:00
    6:30 10:282:10:00
    7:00 11:162:20:00
    8:00 12:522:40:00

    Frequently asked

    How far is the 20K?

    20000 metres, which is 20.00 km or 12.427 miles.

    What pace do I need for a specific time?

    Divide the target time by the distance in kilometres. The calculator does it in the "pace needed" row.

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