Gross Rent Multiplier for Apartment Buildings: How to Use It (and When It Lies)
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Gross rent multiplier (GRM) is the purchase price divided by the building's gross annual rent. A $3,000,000 building that brings in $400,000 a year of rent has a GRM of 7.5. GRM is useful as a first screen when you compare similar buildings in the same area, because it needs only two numbers. It is not a valuation: it ignores vacancy, operating expenses, other income and who pays the utilities, so a deal that looks cheap on GRM can be expensive on net operating income.
This guide shows the math, a worked example where GRM points the wrong way, and how to use it next to cap rate and price per unit. For the full underwriting picture, start with multifamily underwriting basics.
How do you calculate gross rent multiplier?
Divide the price by the gross annual rent.
GRM = purchase price / gross annual rent
Gross annual rent is the rent the building is scheduled to collect in a year at current leases, before vacancy and before expenses. If you have a rent roll, add up the current monthly rent of every unit (count vacant units at the rent you can realistically get) and multiply by 12.
You can also run it backwards to estimate a price: multiply gross annual rent by a GRM you have seen on similar sales. That is a rough check, not an offer price.
| Input | Example (made up) |
|---|---|
| Units | 24 |
| Average in-place rent | $1,250 a month |
| Gross annual rent | 24 x $1,250 x 12 = $360,000 |
| Asking price | $2,880,000 |
| GRM | $2,880,000 / $360,000 = 8.0 |
Annual or monthly GRM?
Both appear in listings. Annual GRM uses yearly rent (the example above is 8.0). Monthly GRM uses one month of rent, so the same building shows 96.0. Neither is wrong, but mixing them makes a building look 12 times cheaper or more expensive. When a broker quotes a GRM, ask: annual or monthly, and in-place or pro forma rent?
Where does GRM mislead you?
GRM sees only the top line. Everything below it changes value:
- Utilities. A building where the owner pays water, sewer, trash and heat has much higher expenses than one where tenants pay their own. See ratio utility billing for how owners recover some of that cost.
- Property taxes. A sale can reset the assessed value. Read property tax reassessment before you trust the seller's tax line.
- Vacancy and bad debt. Scheduled rent is not collected rent. See economic vs. physical occupancy.
- Other income. Laundry, parking, pet fees and storage add to NOI but are not in gross rent.
- Condition. Deferred maintenance and capital needs never show up in GRM.
A worked example: same GRM, different value
Both buildings below are made up to show the math. They sit in the same submarket, have 24 units and the same rent, and the seller asks the same price for each.
| Topic | Building A | Building B |
|---|---|---|
| Gross annual rent | $360,000 | $360,000 |
| Price | $2,880,000 | $2,880,000 |
| GRM | 8.0 | 8.0 |
| Vacancy and bad debt (6%) | $21,600 | $21,600 |
| Other income | $14,000 | $4,000 |
| Who pays utilities | Tenants (RUBS) | Owner |
| Operating expenses | $140,000 | $186,000 |
| NOI | $212,400 | $156,400 |
| Cap rate at asking price | 7.4% | 5.4% |
Same GRM, but Building A produces $56,000 more NOI a year. If similar buildings trade at a 6.5% cap rate, A is worth roughly $3,268,000 and B roughly $2,406,000. GRM would have told you they are the same deal.
When is GRM useful?
- Sorting a long list. When you look at dozens of listings, GRM quickly flags which ones deserve a full underwrite.
- Comparing true lookalikes. Same block, same age, same utility setup, same unit mix. In that narrow case GRM tracks value reasonably well.
- Checking a broker's story. If the asking price implies a GRM far above recent sales nearby, ask what justifies it.
- Small buildings with thin data. For a 6 to 12 unit building with poor books, GRM against recent sales can be one of the few comparisons you have. Still rebuild the expenses yourself.
How GRM fits with cap rate and price per unit
Use three numbers together, in this order:
- GRM to screen: is the price in the range of nearby sales for the rent?
- Price per unit to compare against sales of similar buildings.
- Cap rate on your own NOI, built from the rent roll and T12, to decide what you will pay.
Lenders size loans from NOI and debt service coverage, not GRM, so the cap rate step is the one that decides whether the deal works. You can test a price, income and loan in the cap rate and DSCR calculator.
How DoorRaise fits in
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FAQ
What is a good gross rent multiplier for an apartment building?
There is no single good number. GRM depends on the market, interest rates and how expensive the buildings are to run. Compare a building's GRM only with recent sales of similar buildings in the same area, and confirm with a cap rate on real NOI.
Is a lower GRM always better?
No. A low GRM can mean a bargain, or high expenses, owner-paid utilities, a rough location or a building that needs major work. Look at why it is low before you treat it as a discount.
What is the difference between GRM and cap rate?
GRM divides price by gross rent. Cap rate divides net operating income by price, so it includes vacancy and operating expenses. Cap rate is the better measure of value; GRM is a faster screen.
Do lenders use GRM?
Commercial and agency multifamily lenders size loans on NOI, debt service coverage and loan to value. GRM may show up in an appraisal's comparable sales, but it does not set the loan amount.
Next step: build NOI line by line with multifamily underwriting basics.
Sources
This article is general information, not investment, legal or tax advice. The examples are made up to show the math. DoorRaise is not a law firm, broker-dealer, investment adviser or funding portal.