# Permanent magnet magnetic field strength dependency on distance

I've been trying and failing to find any sources or references on how a simple circular magnet of the kind you'd attach to your fridge depends on distance.

I'm sort of expecting a r^-3 dependence (because we can probably sort of model that as a dipole?) with some sort of sinusoidal dependence on the angle. But I'm happy to analyze simple cases.

• Like you said, I think that as a first approximation you can simply model it as a magnetic dipole, at least for distances from the magnet which are large compared to the physical size of the magnet. – user93237 Oct 20 '18 at 18:13
• According to magnetsales.com/design/faqs_frames/faqs_2.htm , it's less than $r^{-3}$ for circular magnets. – HiddenBabel Oct 20 '18 at 18:51