Sprint University

Bo Jackson's 40-yard dash

There is no verified official 40 time for Bo Jackson. The famous 4.12 was not run at the 1986 NFL Combine, which he declined to attend. Jackson has said he ran an electronically timed 4.13 at a pre-draft workout at Auburn; former NFL executive Ron Wolf recalls a hand-timed 4.16 there. Neither result was published officially.

40-yard dashJackson's own account: electronic, Auburn pre-draft workout, 1986Claimed
4.13
40-yard dashRon Wolf's recollection: hand-timed, same workoutClaimed
4.16
40-yard dashWidely repeated; no record of it being runUnofficial
4.12
100mAt Auburn (Wikipedia; date and wind not given)Unofficial
10.39

Compare yourself to Bo Jackson

The converter starts at Bo Jackson's 40 time. Put in yours to see your speed and how far behind (or ahead of) Jackson you'd finish.

Estimated 100m
9.41 s
from the gun, incl. 0.15 s reaction
Average speed over 40 yd
19.8 mph
31.9 km/h · 8.86 m/s
Estimated top speed
27.9 mph
44.9 km/h · 12.46 m/s

These numbers are estimates from a sprint velocity curve fitted to Usain Bolt's official Berlin 2009 splits. A 40 is timed from first movement and often by hand, so football 40s convert to optimistic 100m times. How the estimate works

You vs. the fastest, over 40 yards
The gap when the winner crosses the line.

Where the 4.12 came from

A 2021 Raiders.com investigation found that The Sporting News reported in February 1986 that Jackson declined his invitation to the scouting workout in New Orleans. Around the same time, UPI described him as capable of a 4.12. Nobody had timed him at 4.12, but that is the number that stuck.

Jackson's own account is a 4.13 on an electronic timer at a regional workout in Auburn's indoor facility. Former NFL executive Ron Wolf remembers the same session but a hand-timed 4.16. Other scouts reported hand-held stopwatch times even faster, which says more about hand timing than about Bo.

What his track times suggest

Wikipedia lists a 10.39 100m at Auburn and a 6.18 60-yard dash. Run through our model, a 10.39 100m converts to roughly a 4.50 40 from a track start, while a 4.13 40 converts to about a 9.4 100m. Most of that gap comes from how the two events are timed. A 40 starts on the runner's own movement, and 40s before 1999 were hand-started and hand-stopped, so they read fast.

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The Sprint University app builds your speed work around the times you run now and adjusts every session to how recovered you are. The program comes from Lawrence L.O. Johnson, a 6× NCAA All-American and Team USA sprinter.

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Bo Jackson is mentioned for comparison only and is not affiliated with Sprint University.

Sources

  1. Raiders.com: “Bo knows 40-yard dashes” (Jerry Knaak, 1 Mar 2021)
  2. Wikipedia: Bo Jackson (4.13 account; track times at Auburn)
  3. Wikipedia: 40-yard dash (36.576 m; Combine hand-start/electronic-stop timing since 1999)
  4. Helene & Yamashita, “The force, power and energy of the 100 meter sprint,” Am. J. Phys. 78, 307 (2010): Berlin 2009 10 m splits and 0.146 s reaction (IAAF data)
  5. Samozino et al., “A simple method for measuring power, force, velocity properties, and mechanical effectiveness in sprint running,” Scand. J. Med. Sci. Sports 26:648–658 (2016)