it will depend on the Mint you are transacting with.

In Minibits, click on Settings -> Manage mints.

I will assume you fund one already with some sats to transact. Select it or click on it, once you do that a small menu will open, select "Mint information page"

All the information about that Mint are there for all its users, including the limits for deposits and withdraw, in the default Mint both are capped at 1,000,000 sats and the minimum to 0... So 1 sat

Hope this helps