"Dave Liquorice" wrote in
ill.network:

An adult mouse will get through a 1/2" dia hole no problem, 3/8" will
slow it down but will still get through. Rats no problem at an inch,
3/4" is starting to get tight.

A hole a rat has made for itself will be around 1 1/2" dia, for a
mouse 3/4" dia or there abouts.

The rat that came to my garden made holes that were about 3 inches. It was
definitely him - I saw him at it. Mind you, it was a mega-rat - about the
same size as my rabbits. They aren't all that huge, luckily.

Victoria