OK,
Generally on this it is just an estimate and you would give an answer and say, "For budgeting purposes the cost is an average of £0.30 pence per person per day."
This on average covers for toilet roll, paper towels, soap.
It depends on the use, frequency, number of staff, visitors and the correct usage.
We have many contracts and have kept records of the quantity that gets used. Obviously again its only an estimate.
I will give two example of our records.
1 x office - 14 staff. just under 1 box of paper towels per month - average size box is 2600 sheets - 2888.
1 x office 14 staff - toilet rolls just under 36 rolls a month.
1 x office 14 staff 2 x pump soaps a month
Example 2
1 x office - 100 staff toilet roll equals about 150 rolls a month
1 x office 100 staff 6 - 9 pumps soaps
these are an average. True records so this might help you. If you supply these keep them under lock and key and charge per box. Any go missing they get charged or your cleaner is stealing. You have to see the type of environment as some "rough" environments will stuff loo rolls down the toilet as well as paper towels ... if you get my drift and will be more expensive.
If they have this problem, there are ways of dealing with it.
Dave