GRM for BP Rental Property Calculator

[Cole Swartz]

When calculating the GRM, why does the BP Rental Property Calculator use the Purchase Price as opposed to the ARV? As it currently stands, it uses the after-rehab rent values for the GSI in the denominator, but uses the before-rehab value of the home (purchase price) in the numerator? If you are going to use the after-rehab rent values, should you not also use the ARV for the value of the home? Not too big of a deal, but just curious.