40-Yard Dash

The 40-yard dash is football's signature speed test. This calculator turns your stopwatch time into an average speed you can actually picture.

How the calculation works

Forty yards is exactly 36.576 meters, because the international yard has been defined as 0.9144 m since 1959. The calculator divides that distance by your time to get meters per second, then multiplies by 3.6 to express it in kilometers per hour: v = 36.576 / t × 3.6.

There is a single input: your time in seconds, between 3 and 10, in steps of 0.01 s. Enter the time over the full 40 yards, from the first movement to crossing the line. If you ran 40 meters instead, the formula does not apply, since that distance is about 3.4 m longer and the speed would be overstated.

Keep in mind that the result is the average speed over the whole run, acceleration included. An athlete’s top speed near the finish is clearly higher, and the speed over the first 10 yards is lower. That is why the 40 measures starting speed and acceleration more than maximum velocity.

Worked example

The default time is 4.50 s. Average speed: 36.576 / 4.50 = 8.128 m/s; multiplied by 3.6 that is 29.26 km/h, or about 18.2 mph. Drop the time to 4.40 s and the average rises to 29.93 km/h (about 18.6 mph), so each tenth of a second is worth roughly 0.7 km/h over this distance.

Things to keep in mind

• Only compare times recorded the same way. Hand timing is usually faster than electronic timing, because the timer reacts late to the start and tends to stop the watch early.
• The start matters. At the NFL Scouting Combine athletes begin from a three-point stance and the clock starts on their first movement; a standing or flying start produces a time that is not comparable.
• Surface, footwear and wind can shift results by hundredths or even tenths of a second. To track progress, retest under the same conditions.
• Timing the 10-yard split (9.144 m) as well tells you much more about your first steps than the full 40 alone.