It depends on the person and the facility. There are inmates that live on a lot less and and there are inmates that can spend up to the limits on everything and use $300/month or more. What matters is what you can afford, as the prison offers enough for an inmate to subside, what you give is extra. Be careful over-extending yourself as inmates can be good at making loved ones on the outside feel guilty and have you spend more than you can.
https://www.inmateaid.com/ask-the-inmate/so-my-husband-is-in-madison-work-camp-i-have-been-sending-100-a-month-and-packs-every-quarter-it-never-seems-like-its-enough-he-says-100-a-month-is-nothing-how-much-money-is-really-needed-for-hygiene-and-snacks#answer
Accepted Answer Date Created: October 13,2014