Size of magnets for 20 and 25mm bases?

So i've scoured the internet for a good answer, but I am getting back a lot of conflicting answers.

If i'm buying rare earth magnets to make my own magnetic bases, how deep (tall) should the magnets be so they are flush with the bottom of my models?

The internet has told me 1.5mm, 2mm, or 1/16 inch all might fit, but there are also a lot of people that also are showing their models hovering above their movement trays. Any suggestions?

 

Ehh break out a ruller...
& eyeball it real good.

 

It would actually be cheaper to get some magnets of all three sizes than to get a micrometer. Although i guess if I got the micrometer than I would never need to ask stuff like this again.

I figure that someone here has to have some experience with this though.

 

I'm thinking that Slightly smaller is better than slightly larger.
(glue takes up space too)

 

If you need it to be spot on I'd say just stick in a few layers of plasticard, file em down till they sit flush with the base then drill it and put a magnet in there

Other option, get one of each base type and cut them down the middle so you have a cross section, hold it up against your ruler and there you have it.

Also - just lining my own magnets up against a saurus' base it would appear 2mm deep magnets are pretty much bang on for those

 

Okay so curiosity piqued.

I've just fiddled with some magnets and the bases and 2mm deep is what you need. I've got a 25mm base stuck on the blade of a knife without any gap between the two. 20mm are the same depth and will be the same.