How do I estimate the requirements for my laundry?

Although there is a definite formula for how much laundry can be retrieved/washed/folded/delivered at once, there are a lot of factors in the efficiency. These are:

• Number of people working (or available to work) in the laundry (this includes janitors and inmates)
• For inmates, the "work" regime determines how long they can work
• For janitors, other work required (ie mopping/cleaning) determines how much time they can spend on laundry
• The proximity of laundry services to the cells. It seems like it shouldn't matter, but travel time makes a huge difference. If it takes 5 minutes for a person to deliver a basket of clothing to a cell block, that's 1/12th of that hour spent.
• Where the workers (janitors/inmates) are coming from when the work regime begins - if its far away, again travel time plays a factor.
• If you have any locked jail doors (which I hope you do), if they are not remote/automated, they will need to be unlocked manually for the janitor/inmate to get through.

With all those factors in mind, I usually just keep an eye on the following factors during the course of the game:

• Are there a lot of cells with dirty uniforms laying on the beds, if so, we need more people with baskets collecting dirty laundry
• Are there piles of clean/folded uniforms in the laundry room that aren't being delivered? Again we need more baskets and/or workers to deliver the uniforms.
• Are there piles of dirty laundry in baskets or on the floor in the laundry? If so, we probably need more washing machines.
• Are there piles of clean (but wrinkled) uniforms in the laundry? If so we need more ironing boards and/or workers to iron the clothes
• Are people complaining of the "Clothing" need? If so, one of the above things is not happening fast enough, so see where the chokepoint is and remedy it.

One thing to note, is that laundry is a huge (did I say HUGE) factor in prison contraband. I have a guard, and a dog guard, patrolling in the laundry room at all times, and I also have a metal detector at the laundry room door, with a guard close by.

From The Prison Architects wiki:

• 1 basket can service 16 inmate cells
• 1 Laundry machine can service 4 baskets
• It takes 2 ironing boards to service 1 laundry machine Summary: 1 Laundry Machine + 2 Ironing Boards + 4 Laundry Baskets + 5 workers = laundry service for 64 inmates
• An efficient working room for 20 workers is 80 tiles (10x8 or equivalent) with 4 Laundry Machines, 8 Ironing Boards and 16 Laundry Baskets. An extra machine and some extra baskets won't hurt and may be used by janitors. 4 to 5 machines is enough to service 256 prisoners. For a larger prison, build a second room to allow 20 more worker assignments. (make sure the tiles marked for each laundry room do not touch or overlap or the game will consider it one large room)