50K ultra pace and finish time calculator

The 50K ultra is 50000 metres — 50.00 km, or 31.069 miles. Enter a pace and this gives the finish time, or work backwards from a target.

Finish time
5:25:00
= Exact 50K ultra pace
Speed
9.231
Pace per mile
10:28
Pace per kilometre
6:30
Pace needed for the target time
0:00
Halfway split
2:42:30
Quarter split
1:21:15
Pace per 400 m lap
2:36
Track laps
125.00
Speed in metres per second
2.564
Show the working
  1. Pace, minutes per km = 6.5
  2. Plus seconds = 0
  3. Or a target time, hours = 0
  4. Target minutes = 0
  5. distance_m = 50000 = 50 000
  6. distance_km = 50 000 / 1000 = 50
  7. Pace per kilometre = 6.5 * 60 + 0 = 390
  8. Finish time = 390 * 50 = 19 500
  9. Speed = 390 > 0 ? 3600 / 390 : 0 = 9.230 77
  10. Speed in metres per second = 9.230 77 / 3.6 = 2.5641
  11. Pace per mile = 390 * 1.609344 = 627.644
  12. target_seconds = 0 * 3600 + 0 * 60 = 0
  13. Pace needed for the target time = 50 > 0 && 0 > 0 ? 0 / 50 : 0 = 0
  14. Halfway split = 19 500 / 2 = 9750
  15. Quarter split = 19 500 / 4 = 4875
  16. Pace per 400 m lap = 390 * 0.4 = 156
  17. Track laps = 50 000 / 400 = 125

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 50K ultra

    Pace per km Pace per mile Finish time
    3:30 5:382:55:00
    4:00 6:263:20:00
    4:30 7:153:45:00
    5:00 8:034:10:00
    5:30 8:514:35:00
    6:00 9:395:00:00
    6:30 10:285:25:00
    7:00 11:165:50:00
    8:00 12:526:40:00

    Frequently asked

    How far is the 50K ultra?

    50000 metres, which is 50.00 km or 31.069 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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