Gross potential rent (GPR) is the ceiling: what the property would collect if every unit were occupied every day of the year at full market rent. A four-unit building where each unit commands $1,500 a month has a GPR of $72,000 a year. No property actually collects its GPR — vacancy, turnover gaps, non-payment, and below-market leases all pull real collections below it.
GPR earns its place as a baseline, not a forecast. Measuring actual collections against it produces the economic-loss picture: vacancy loss, credit loss, and loss to lease each explain part of the gap. That decomposition is useful because each gap has a different fix — vacancy is a leasing problem, credit loss is a screening and collections problem, and loss to lease is a renewal-pricing problem.