Estimating rents when renting a house separately

[Jason Wu]

Hi BPers!

I'm new to real estate investing and have been looking at rental properties in the greater Seattle area. To achieve better cash flow, I was considering renting a house separately and hoping to get some advice on how to set the rent correctly. Below are some data points:

2-story SFH (3b3b, 1,800 sqft): 2b2b (w/ kitchen) on the upper floor and 1b1b (w/ kitchen) on the lower floor; each with separate entrance and only laundry is shared

The estimated rent for the entire house is $3,500, and a standalone 2b2b house can be rented at $2,800 and 1b1b at $1,800, how should I set the rents if I want to rent the upper and lower floor separately? Directionally I know they should be lower than the standalone rents but not sure by how much.

Would love to hear your thoughts!