I am a Section 8 landlord in Tampa.
Each county has their own county housing department. The voucher amounts are set with two variables.
First, the house gets a value based on the number of bedrooms in the house and the market rate for rent in that neighborhood (which can be different town by town). There is a maximum amount set by the county for the number of bedrooms. In Hillsborough County, you can call the housing department and ask for the max amount per bedroom.
Second, the person or family holding the voucher is assigned a voucher amount based on how many bedrooms they 'need' for there dependents and dependent ages. So a family of 4 many receive a 2 bedroom voucher or possibility a 3 bedroom voucher of the family has two boys vs a boy and a girl, since they can not stay in the same room. To make the matter a bit more complicated the amount of the voucher can change if tenant is paying there own electrical or water. Also, if the family is employed or has other aid such as social security or disability, the voucher holder will pay a portion of the rent. For example if the rent is $1000 the voucher holder may be required to pay $330. A lot of times this amount is about 1/3 of their monthly earnings.
When interviewing potential voucher holding tenants you can ask them their voucher amount. They should be able to tell you 1- the number of bedrooms in their voucher 2- the maximum dollar amount of their voucher with and without electrical and water 3- the portion they are required to pay.
In summary, call the housing department for the amounts and interview the tenants to get the most rent value for your particular home.
I hope this helps...