The GRM formula
GRM = purchase price ÷ annual gross scheduled rent. It measures price against every dollar of rent with no expenses subtracted, which is why it screens in seconds. Lower is better: the 1% rule states the same rent-to-price test as a percentage, and a GRM near 8.3 answers it with a pass.
A $300,000 property collecting $3,000 a month ($36,000 a year) has a GRM of 8.3, 8.3 years of total rent to "pay for" the building.
Worked example
GRM ranks the three listings in one pass: A is 10.2, B is 14.9, C is 7.9. On price per dollar of rent, C wins and B is thin, but GRM sees no expenses, so a low number is a candidate, not a verdict.
Three listings, one spreadsheet. A: $220,000 at $1,800/mo, annual $21,600, GRM 10.2. B: $410,000 at $2,300/mo, $27,600, GRM 14.9. C: $180,000 at $1,900/mo, $22,800, GRM 7.9. By GRM alone, C is the best price-for-rent deal and B is thin. The caveat is built in: B might be a $500-a-year insurance, $1,200 taxes property while C carries $4,000, GRM never sees expenses. That is why it screens and cap rate decides.
Worked example 2: same GRM, two very different deals
Two buildings, one number. Both list at $360,000 collecting $3,000 a month, so both show a GRM of 10.0, price divided by $36,000 of annual rent. On the screening ratio they are the same deal. On expenses they are opposites, and GRM cannot see the difference.
Building A: taxes $4,200, insurance $1,400, maintenance $2,800, vacancy 5% at $1,800. Total operating expenses $14,400, a 40% load, so NOI is $21,600 and the cap rate on $360,000 is 6.0%. Building B: same taxes and insurance, but a $700-a-month HOA adds $8,400 a year and an aging building lifts maintenance to $3,600. With the same $1,800 vacancy, expenses run $19,800, a 55% load, so NOI is $16,200 and the cap rate is 4.5%.
Same GRM, one and a half points of cap rate apart. At your 6% target, Building A is priced correctly and Building B would have to sell for about $270,000, $16,200 ÷ 0.06, to offer the same return. The $90,000 gap between the two prices is invisible in the ratio that screened them.
The lesson: GRM prices the rent stream, and two identical rent streams can sit on very different expense structures. Use the multiple to find candidates, then rebuild both expense stacks before you rank them. The number that looked identical was never the decision.
Case study: using GRM to screen 20 deals in 30 minutes
GRM earns its keep as a first-pass filter, and the workflow is simple. Sold comps in this submarket trade between GRM 10 and 11, so the screen has three lanes: investigate below 9, pass between 9 and 12, reject above 12. Twenty listings, thirty minutes, one division each.
Listing 1: $310,000 at $2,400 a month, $28,800 a year, GRM 10.8. Inside the lane, so it moves to underwriting. Listing 2: $455,000 at $2,600, $31,200, GRM 14.6. Rejected, the seller wants coastal money for a cash-flow market building. Listing 3: $189,000 at $2,100, $25,200, GRM 7.5. Below 9, so it goes to the investigate pile: at that price the rent roll, the roof, or the tenants are telling a story the number cannot.
Listing 4: $265,000 at $1,900, $22,800, GRM 11.6. Passes near the top of the lane, worth underwriting before the better-looking ones. Listing 5: $520,000 at $3,400, $40,800, GRM 12.7. Rejected, just over the line, and a deal that barely fails the screen rarely survives expense underwriting.
Final count: two pass, one investigate, two rejected. Three buildings move forward from twenty, and the screening took one division per listing. The rejected twelve cost nothing but minutes, which is the entire point: GRM is not a decision, it is the filter that decides where your underwriting hours go. The three survivors now get expense sheets, and the cap rate side ranks them for real.
What is a good GRM?
Under 12 is a common benchmark for long-term residential, under 8 is strong cash-flow pricing, and 15–20+ means the thesis is appreciation rather than rent. Good is relative: benchmark against comps in the same market and property class.
Long-term residential: under 12 is a common "decent" line, under 8 is strong cash-flow territory and mostly found in the Midwest and South. 15–20+ is typical for coastal metros and means the investment thesis is appreciation or renovation (BRRRR), not rent. Commercial investors use the same idea with 10× multiples on NOI, not rent, do not mix the two.
GRM versus cap rate
GRM screens; cap rate decides. GRM needs only price and rent, so it triages a hundred listings; cap rate needs expenses, so it settles the shortlist. Use them in that order and neither one's blind spot costs you.
Cap rate requires expenses and is more accurate; GRM exists because you often only have the rent column. Use GRM to triage hundreds of listings, then pull the survivors into full underwriting. It also quietly encodes the expense ratio: if GRM is 8 and the market cap rate is 6%, expenses are eating about 25% of gross rent, an instant check on whether a seller's NOI looks plausible. For the rest of that pipeline, the cost side itself lives in NOI, and the money you actually keep after financing shows up in cash-on-cash. Neither ratio follows the property past year one, so the multi-year return on the same property is what you open once a deal survives the screen.
GRM vs GIM vs cap rate: three ratios, three jobs
These three ratios form a ladder, each one step deeper into the money. GRM counts rent only, GIM counts every income line, and cap rate counts income after expenses. Each step needs more paperwork and answers a sharper question.
GRM needs two numbers and screens in seconds; GIM adds the side income a rent roll hides; cap rate needs the full expense sheet and decides the deal. Here is what each counts and when to reach for it.
| Ratio | What it counts | Formula | Includes expenses? | When to use |
|---|---|---|---|---|
| GRM | Gross scheduled rent only | price ÷ annual gross rent | No | Screening many listings fast |
| GIM | All gross income, rent plus laundry, parking, storage | price ÷ gross annual income | No | Buildings with meaningful side income |
| Cap Rate | Income after operating expenses | NOI ÷ price | Yes | The decision number on a shortlist |
Screen with GRM, compare income-heavy buildings with GIM, and let cap rate make the call.
GRM as a same-market arbitrage check
GRM compares like to like. A fourplex at 7.5 beside comps at 9.0 and 9.5 is either the deal of the year or hiding a reassessment or a deferred roof. The spread tells you how much anomaly to investigate. Never compare across property classes.
GRM's real power is comparing like to like, the same building type, same submarket, same expense class. A fourplex at GRM 7.5 next to two renovated comps at 9.0 and 9.5 is either the deal of the year or hiding something: a tax reassessment, a deferred roof, a rent gap the "renovation" comps already captured. The spread tells you how much anomaly to investigate. What GRM cannot do is compare a Class-A new build with HOA dues against a no-HOA 1970s triplex at the same number, the second yields better on the identical ratio. Always compare GRM within a risk class, then use the cap rate to rank between classes.
Converting GRM into a quick cap-rate estimate
Cap rate ≈ (1 − expense ratio) ÷ GRM. At a 40% expense ratio, a GRM of 9 implies a 6.7% cap and a GRM of 7 implies 9.3%, the one-line bridge from a listing's price and rent to the metric that includes expenses.
Once you know the building's expense ratio (say 40%, check the rent roll, not the marketing), you can estimate cap from GRM in your head: cap rate ≈ (1 − expense ratio) ÷ GRM. GRM 9 with 40% expenses gives 0.60 ÷ 9 = 6.7%. GRM 7 with 35% gives 9.3%. This is the back-of-the-envelope move experienced flippers use in the parking lot at an open house, one number from the listing plus a known expense norm produces the cap rate before the drive home. The full formula lives in the cap rate calculator, and note that no lender sizes a loan on GRM. Loan files are underwritten on NOI and debt service coverage instead.
Typical GRM by property type
Expense reality means the "good GRM" line moves by building class, even within one market. Single-family long-term: 10–14 in most metros, sub-9 is the Midwest cash-flow signature. Two-to-four-unit: 8–11, the unit count does that, same roof, four rents. Small condos: 12–18, because HOA and insurance kill the net income GRM pretends to ignore, so use condo GRMs only to compare condo to condo. Owner-occupied duplex (live in one, rent one): the rented half's GRM looks terrible at 15+ while the effective cost of housing is unbeatable, that is an appraisal artifact, not a bad deal. House-hacking math only becomes visible in cash-on-cash. The discipline is simple: one property class, one GRM yardstick, never mix classes in the same comparison, and when in doubt, pull everything into the cap rate side by side in the compare table.
How GRM differs by market type
Property class sets one layer of the yardstick, market type sets another. The same building class carries different multiples in different markets, and the number only means something next to its own market's comps.
Coastal metros run the highest GRMs, commonly 15 to 20, because owner-occupant demand and appreciation expectations bid prices up faster than rents. The multiple prices the future, not the rent. Midwest and Southern cash-flow markets run 6 to 10, where the multiple prices the rent stream itself and appreciation is a bonus rather than the thesis.
Sunbelt growth markets sit between the two: prices reflect both current rent and in-migration, so GRMs land above the cash-flow markets without reaching coastal levels. Rural markets vary the widest of all. Sold comps are thin, one odd sale can move the local median, and a GRM there is only meaningful against recent same-class sales from the same county.
The rule across all four: never compare GRM across markets on the number alone. A 15 in a coastal metro and a 9 in the Midwest can both be fairly priced, and a 9 in the Sunbelt can be rich or cheap depending on its own comp set. Benchmark inside the market, then let expenses decide.
Monthly vs annual GRM: which convention you're reading
Annual GRM is the standard: price ÷ annual rent, which is what brokers, appraisers, and comps quote. A monthly GRM (price ÷ monthly rent) exists and runs about 12× bigger, near 96 for the same property, so mixing the two makes a deal look roughly twelve times cheaper or pricier than it is.
The tell is the number's size: 8 to 14 is annual, the high eighties or nineties is monthly. When a listing quotes a multiple near 100, divide by 12 before comparing. 96 monthly is the same 8.0 annual. Keep the rent basis consistent too: scheduled gross rent, never effective rent after vacancy, since ignoring everything below the top line is the ratio's whole point.
From GRM to gross yield and the 1% rule
Gross yield is the inverse of GRM: 1 ÷ GRM. A GRM of 8 is a 12.5% gross yield, 10 is 10%, 5 is 20%. Lower multiple, higher yield. The 1% rule is the same relationship at a fixed floor, and a GRM of 8.3 is where it sits.
Move between the three with two divisions: gross yield = 1 ÷ GRM, and rent as a percentage of price = 8.33 ÷ GRM. A GRM of 10 is rent at 0.83% of price, and a GRM of 8.3 is rent at or above 1% of price, the 1% rule itself. Gross yield stays the cruder measure because it still ignores every expense: it prices the rent stream, not the return.
Implied value and offer ceiling
Implied value is annual rent × market GRM. If comparable buildings trade at a GRM of 9 and the property collects $36,000 a year, the comp-derived ceiling is about $324,000, a price range from rent, and the fastest sanity check you can run at a kitchen table.
Use sold comps, not asking prices, to set the market GRM. Listings are wishful thinking. Then hold the two sides apart: a market GRM applied to sub-market rent produces a ceiling the owner will never accept, and above-market rent at a market GRM just restates the seller's optimism. Rent it at what the unit actually collects today, multiply by what similar buildings actually sold for, and you have a ceiling that survives negotiation. Treat it as a range, not an appraisal: it caps what you can pay before the rent stops justifying the price, and it knows nothing about the roof, the tenant, or your financing.
Three GRM mistakes that mislead investors
Three mistakes turn a screening tool into a trap: pricing the multiple off asking rent, comparing across property classes, and reading every low GRM as a bargain. Each one distorts the ratio in a predictable direction. Here is each in real numbers, the cost, and the fix.
Using asking rent instead of market rent: a seller asks $2,400 a month on a unit the comps support at $2,000. At a $288,000 price, the asking-rent GRM is 10.0, right on the market line. The market-rent GRM is 12.0, above the 11 comp line, and the income supports a price near $240,000, not $288,000. The cost is roughly $48,000 of overpayment. The fix: verify rent from leases and comps before trusting any multiple.
Comparing across property classes: a house at GRM 13 next to a fourplex at GRM 9 reads like the fourplex is cheaper per rent dollar, but owner-occupants bid houses up and investors bid small multifamily down, so the two multiples come from different buyer pools. The fourplex also carries the heavier expense load, so the net yields converge. The cost is chasing an SFR-priced return on multifamily expenses. The fix: compare GRM only within the same class, then rank across classes on cap rate.
Treating a low GRM as automatically good: a fourplex at GRM 7.1, $210,000 at $2,450 a month, beside comps at 9.5 looks like a steal. The roof and plumbing need $18,000, and two month-to-month tenants sit $200 under market, so the real basis is $228,000 and the rent roll explains the discount. The cost is buying the problem that created the number. The fix: investigate the spread before celebrating, the arbitrage check that separates a mispriced gem from a priced-in headache.
Frequently asked questions
14 answers, no funnel.
What is a good gross rent multiplier?
For long-term rentals, generally below 12; below 8 is strong cash-flow pricing. High-cost metro markets commonly run 15–20 because rent there is a poor proxy for income net of expenses.
GRM vs cap rate, which should I use?
Cap rate if you have credible expenses; GRM when you are screening fast and only have price and rent. GRM is a first-pass filter, cap rate is the decision number.
Does GRM work for short-term rentals?
Only with realistic net nights. Airbnb gross numbers inflate apparent GRM because you subtract cleaning, platform fees, and vacancy, which turn GRM back into a disguised cap rate.
Why is GRM used at all if it ignores expenses?
Because you can get rent without a rent roll. Listing platforms publish price and estimated rent, so GRM ranks a hundred buildings in ninety seconds; the two survivors then get full expense underwriting.
What is the difference between GRM and GIM?
GRM counts rent only; the gross income multiplier (GIM) includes every income line, like laundry, parking, and storage. GIM runs slightly lower on the same building, so never compare one against the other.
Is a lower GRM always better?
No. A GRM far below the local comp set is either the best-priced building on the street or a warning: deferred maintenance, weak tenants, or a rent roll that will not hold. Ask which before you celebrate.
Which metric do lenders use, GRM or cap rate?
Neither as a screen: GRM barely appears in a loan file. Lenders size investment loans on net operating income and debt service coverage, so a strong GRM tells you nothing about whether the loan closes.
Why do single-family rentals have higher GRM than multifamily?
Because owner-occupants bid against investors. A house a family will live in competes with buyers who never run the rent math, while a five-unit building competes only with investors, which compresses its GRM toward the income it produces.
Is GRM comparable across different markets?
Only loosely. Coastal metros commonly run 15–20 while Midwest and Southern cash-flow markets commonly run 6–10, so the same multiple means different things in each. Benchmark within one market, never across.
Does GRM include property taxes?
No. GRM divides price by gross rent alone, before every expense, taxes included. Two buildings with the same GRM can carry very different tax bills, which is why cap rate settles the shortlist.
Can I use GRM for commercial property?
Yes, but commercial trades on NOI, not gross rent, so investors quote a multiple of NOI instead. A GRM on a strip mall or office building compares poorly against commercial comps. Keep GRM to residential screening.
How do I find my market's GRM?
Pull sold comps, not listings: sale price divided by each property's annual rent. The median of five to ten same-class sales is your market GRM, the yardstick for screening and for pricing your own offer.
How do I find GRM?
Divide the property price by the annual gross rent. A $300,000 property renting for $2,500 a month collects $30,000 a year, so GRM is $300,000 ÷ $30,000 = 10.0. Two numbers, one division.
How do I calculate gross rental income?
Multiply monthly rent by 12, and add any other scheduled income like parking or laundry. A property renting for $2,500 a month grosses $30,000 a year before vacancy and expenses. Gross rent is the top line, never the net.