How does a magnet’s strength drop off over distance?
The strength of a magnetic field drops off roughly exponentially over distance.
Here is an example of how the field (measured in Gauss) drops off with distance for a Samarium Cobalt Grade 18 disc magnet which is 1” in diameter and 1/2 “ long.
| Distance, x | Field at Distance, x |
| 0.063 | 2,690 |
| 0.125 | 2,320 |
| 0.188 | 1,970 |
| 0.250 | 1,660 |
| 0.313 | 1,390 |
| 0.375 | 1,160 |
| 0.438 | 970 |
| 0.500 | 810 |
| 0.563 | 680 |
| 0.625 | 580 |
| 0.688 | 490 |
| 0.750 | 420 |
| 0.813 | 360 |
| 0.875 | 310 |
| 0.938 | 270 |
| 1.000 | 240 |