Why It Matters
GRM has been used since the 1950s as a quick way to rank multifamily deals. Lower GRM means cheaper relative to rent. A 6 GRM property is "cheaper" than a 10 GRM property, all else equal. The math is the inverse of gross rental yield: GRM 10 = 10% gross yield, GRM 8 = 12.5% gross yield, GRM 12 = 8.3% gross yield. Commercial and institutional investors prefer cap rate because it accounts for operating expenses. GRM doesn't — it just compares price to gross rent. But for small-multifamily (2-4 unit) deals where expense ratios are similar across properties, GRM is still a fast screening tool. Typical bands: GRM under 8 indicates cash-flowing small multifamily markets (Midwest, parts of the South); GRM 8-12 indicates mixed markets; GRM over 12 indicates appreciation markets.
At a Glance
- Formula: Purchase Price ÷ Annual Gross Rent = GRM
- Inverse of: Gross rental yield. GRM 10 = 10% yield, GRM 8 = 12.5% yield.
- Use case: Small multifamily (2-10 unit) quick valuation screen.
- Typical bands: GRM under 8 = cash-flow markets; 8-12 = mixed; over 12 = appreciation-dependent.
- vs cap rate: GRM ignores operating expenses; cap rate subtracts them. Same market can have similar GRM but different cap rates if expense ratios differ.
- Limitation: Doesn't capture vacancy, taxes, insurance, maintenance — screening tool, not underwriting tool.
GRM = Purchase Price ÷ Annual Gross Rent
How It Works
The basic calculation. A $720,000 fourplex renting for $6,000/month total generates $72,000 annual gross rent. GRM = $720,000 ÷ $72,000 = 10. That's a mid-range multiplier. The lower GRM, the faster the property's gross rent repays purchase price — a 10 GRM property takes 10 years of gross rent to equal purchase price (before expenses); a 6 GRM property takes 6 years. In practice, operating expenses eat 35-45% of gross rent, so true payback is roughly double those numbers. But as a relative comparison within a market, GRM ranks deals effectively.
GRM vs cap rate — when to use each. Cap rate is the superior metric because it subtracts operating expenses before dividing by price. But cap rate requires expense data, which isn't always available on listings or in initial screening. GRM needs only rent and price — both available on every listing. Use GRM for 30-second screening: rank deals roughly by which has the better price-to-gross-rent ratio. Then transition to cap rate once you have expense data (property tax rate, insurance quote, maintenance estimate). Think of GRM as the fast filter and cap rate as the underwriting tool.
Why small multifamily still uses GRM. For 2-4 unit properties, operating expense ratios tend to cluster within a narrow range — typically 35-45% of gross rent depending on age and tax rate. That means GRM and cap rate track each other closely within a given market. An 8 GRM property in Memphis with 40% expenses has a 7.5% cap rate. A 10 GRM property in the same market with the same expense ratio has a 6.0% cap rate. The ranking stays the same; GRM is faster. For commercial or large multifamily where expenses vary widely (utilities, property management, replacement reserves), GRM becomes unreliable and cap rate dominates.
Why GRM falls short in apples-to-oranges markets. Compare an 8 GRM property in Chicago (2.3% property tax) with an 8 GRM property in Nashville (0.7% property tax). Same GRM; very different cash flow. Chicago operating expenses are materially higher because of the tax burden — the true cap rates are ~5.5% vs 7.5%. GRM hid that difference; cap rate revealed it. Always transition from GRM to cap rate before committing capital, especially across markets with different tax regimes.
Real-World Example
Rafael Santos uses GRM to rank three small multifamily deals.
Rafael is looking at 2-4 unit properties across three markets:
- Cleveland OH duplex: $280,000 / $28,800 annual gross rent = GRM 9.7
- Indianapolis IN triplex: $335,000 / $41,400 = GRM 8.1
- Nashville TN fourplex: $725,000 / $68,400 = GRM 10.6
On pure GRM ranking, Indianapolis is cheapest relative to rent, then Cleveland, then Nashville. But GRM ignores taxes. He pulls tax rates:
- Cleveland: 2.3% of value (Ohio is high-tax)
- Indianapolis: 0.9%
- Nashville: 0.6%
Recalculating cap rates (using a 35% base expense ratio plus adjusted tax impact):
- Cleveland: ~5.2% cap (taxes hurt)
- Indianapolis: ~6.9% cap
- Nashville: ~6.4% cap
Cleveland and Nashville switch positions once property tax is properly accounted. GRM suggested Cleveland was good value; cap rate showed Indianapolis and Nashville were actually stronger after-tax returns. Rafael's decision: Indianapolis.
The lesson: GRM is a fast first-pass, but never commit on GRM alone. In markets with outlier tax rates, the GRM ranking can flip when you run full cap rate.
Pros & Cons
- Fastest valuation screen that uses more than one data point
- Only needs price and gross rent — available on every listing
- Inverse of gross yield — same screen, different format
- Works well for ranking comparable properties within a single market
- 70+ years of history in small-multifamily valuation
- Ignores operating expenses — can be misleading across markets
- Taxes, insurance, vacancy, maintenance all invisible
- Cross-market comparison unreliable without cap rate validation
- Commercial and larger multifamily investors use cap rate, not GRM — less universal
- Doesn't account for financing — two deals at same GRM have different cash-on-cash with different down payment
Watch Out
- Cross-market comparison fails: An 8 GRM in high-tax Chicago has much worse cash flow than an 8 GRM in low-tax Nashville. Always re-rank with cap rate when comparing across tax regimes.
- HOA and condo fees are hidden: A $400K condo at $2,400/month has GRM 13.9. If HOA is $400/month, effective gross rent is $2,000/month — GRM collapses to 16.7. Net HOA out of gross rent before calculating.
- Listing rents vs actual rents: Zillow rent estimates are often optimistic. Actual rents at 5-10% below listing estimates shift GRM by 0.5-1.0 points.
- Old housing stock caveat: A 9 GRM property built in 1920 with no renovations in 30 years has higher maintenance ratios than a 9 GRM property built in 1990. GRM doesn't see this; cap rate does.
- Commercial deals don't use GRM: Anything 5+ units or commercial-use gets priced on cap rate. GRM is strictly a residential 2-4 unit convention.
Ask an Investor
The Takeaway
GRM is the old-school screening metric for small-multifamily real estate. Purchase price divided by annual gross rent. Lower = better deal relative to rent. Fast to compute, but ignores operating expenses — so always follow up with cap rate before committing capital. Works well within a single market where expense ratios cluster; fails across markets with different tax burdens. For 2-4 unit screening, GRM is a legitimate first-pass tool. For larger multifamily or commercial, cap rate is the standard. Pair GRM with gross rental yield (same math, inverse format) for a complete screening view.