Gross Rent Multiplier (GRM) Calculator

Gross Rent Multiplier (GRM) is a quick-screening metric used to compare the relative value of income-producing properties. It tells you how many years of gross rent income equals the property’s purchase price. Within one market, a lower GRM means you are paying less for each dollar of rent.

The GRM formula:

GRM = Property Price ÷ Annual Gross Rent

Or equivalently:

GRM = Property Price ÷ (Monthly Gross Rent × 12)

Estimated property value from GRM:

Estimated Value = Annual Gross Rent × Comparable Area GRM

Monthly rent from price and target GRM:

Required Monthly Rent = Property Price ÷ (Target GRM × 12)

Worked example: A duplex is listed at $420,000 and generates $3,200/month in total rent ($38,400/year):

• GRM = $420,000 ÷ $38,400 = 10.94

A comparable duplex sold last month for $380,000 with $3,500/month rent = GRM of 9.05. The listed property’s GRM of 10.94 suggests it is priced 20% above what comparables support.

GRM benchmarks by market type:

There is no good or bad GRM in the abstract, and that is the point of the table above. A 16× is unremarkable in San Francisco and would be an eye-watering price in Toledo. Anyone grading GRM on one national scale is telling you about the city, not the building. The calculator reports which market band your figure lands in, and if you give it a comparable GRM it will tell you what the rent says the property is worth. Getting that comp is the actual work: ask an agent for the sale price and rent roll on three similar buildings that traded nearby in the last year, and divide.

GRM limitations: GRM uses gross rent only. It ignores operating expenses (taxes, insurance, maintenance, vacancy, management), which vary significantly between properties. Two properties with the same GRM can have very different Net Operating Income (NOI) and actual cash flow.

That gap is not small. A building where the owner pays heat and water can run 15 points of expense ratio above an identical one on separate meters, and the two will show the same GRM right up until you look at what is left over. GRM is a screening tool for deciding which listings deserve an afternoon, nothing more.

GRM vs. Cap Rate:

• GRM = simple ratio, uses gross rent, no expenses considered
• Cap Rate = NOI ÷ Price; NOI = Gross Rent − Operating Expenses

Use GRM for quick initial screening; use Cap Rate for serious due diligence.