Ruler Drop Test
The oldest reaction test there is. In a classroom you catch a falling ruler and read off the centimetres. Here we drop it for you, time your catch, and convert it both ways: your reaction in milliseconds and the distance the ruler would have fallen. Five catches, median wins.
From centimetres to milliseconds
A falling object does not move at a steady speed. It accelerates. That is what makes the ruler drop such a neat test: because gravity is constant, the distance the ruler falls is a direct readout of how long you took to react. Double the time and the ruler falls four times as far. The table below shows the conversion for a standard 30 cm ruler.
| Caught at | Reaction time | Verdict |
|---|---|---|
| 5 cm | 101 ms | Lightning |
| 10 cm | 143 ms | Lightning |
| 15 cm | 175 ms | Quick |
| 20 cm | 202 ms | Quick |
| 25 cm | 226 ms | Average |
| 30 cm | 247 ms | Off the end of the ruler |
Notice that catching a 30 cm ruler means a roughly 247 ms reaction, right around the human average. So if a real ruler keeps slipping past your fingers, you are not slow; the ruler is just too short. Want the version without gravity? The standard reaction time test measures the same reflex with a simple click.