The 1% Rule and GRM Are Triage Tools — Not a Verdict on the Deal

There are two numbers you can run on a listing in about five seconds each, and both are useful for exactly one thing: deciding whether a property is worth a real analysis. Neither is a real analysis.

The first is the rent-to-value ratio, better known as the "1% rule": monthly rent ÷ price. If a $200,000 house rents for $2,000, that's 1.0% — the rule of thumb says properties near or above 1% are "worth a look," and those well below it often aren't. The second is the gross rent multiplier (GRM): price ÷ gross annual rent — how many years of gross rent it would take to equal the price. A lower GRM means cheaper relative to gross rent; a higher GRM, more expensive. Both are one division. Both let you scan a page of listings and rank them fast.

Here's what they have in common, and why it matters: both use only rent and price. Nothing else. No property taxes, no insurance, no vacancy, no management, no maintenance, no condition, no financing. Every single thing the last five guides built — effective rent, the expense stack, NOI, cap rate, cash-on-cash, DSCR — is invisible to these screens. And those invisible things are much of what determines the deal's economics. Property-tax burdens can vary materially across jurisdictions; a property at "1%" in a high-tax, high-vacancy market can be a worse deal than one at 0.8% in a low-tax, stable one. The screen can't see the difference. That's not a flaw to fix; it's the nature of a screen.

In fact, the two screens aren't even independent evidence. Look at the definitions: the 1% ratio is monthly rent ÷ price, and GRM is price ÷ annual rent. Since annual rent is just monthly rent × 12, GRM works out to 1 ÷ (12 × the rent-to-price ratio) — the two are inverse transformations of the same price/rent inputs. The 1% rule asks "how much monthly rent do I get per dollar of price?"; GRM flips it to "how many years of gross rent equal the price?" They look like two metrics, but they package one relationship two ways — which is exactly why they share identical blind spots. Running both doesn't double-check anything; it restates the same fact. (One convention note: some versions of the 1% rule add immediate rehab to the denominator. BFC uses monthly rent ÷ purchase price consistently — screens need consistent conventions just like the real metrics do.)

Run the canonical deal through the 1% rule and the limitation lands hard. Monthly rent is $2,200 on a $280,000 price, so rent-to-value is 0.79% — comfortably below 1%. A strict "1% rule" investor would deprioritize or reject it on sight, without ever seeing the full economics. But here's the careful way to say what the underwrite showed: not "the screen was wrong," but that the property is a deliberately thin, near-break-even hold rather than an obviously nonsensical deal — and the screen cannot make that distinction. The 0.79% tells you almost nothing about why the deal is thin or whether that thinness is acceptable for a given investor; only the full underwrite (and the buy/pass decision that follows) can answer that. The reverse can happen too: a property can clear the 1% screen and still fall apart once real taxes, vacancy, management, maintenance, financing, and a reserve are modeled. The screen's real problem isn't that it gives wrong answers — it's that it can't know whether its answer is right.

Its GRM tells the same story from the price side: $280,000 ÷ $26,400 = 10.6. That's a tidy number for comparing this listing to others on gross rent, but it's blind to the fact that two properties with the same GRM can have radically different expense structures — and the expense structure determines how much of the gross rent actually survives. GRM ranks price against gross rent; it says nothing about what's left after the bills.

So use screens for what they're good at: triage. When you're staring at forty listings, the 1% rule and GRM let you deprioritize the least promising and rank the rest, so you spend your real underwriting time on the most promising candidates first. Then — and this is the whole discipline — you underwrite the survivors properly: effective rent, the full expense build, NOI, cap rate, cash-on-cash, DSCR, and the buy/pass decision. The screen narrows the field; the underwrite makes the call. Buying on a screen is buying a deal you haven't actually analyzed.

So the plain-English version: the 1% rule and GRM are fast, cheap, and genuinely useful for sorting listings — and useless as a final answer, because they ignore the economic inputs that separate a good deal from a bad one at the same rent and price. Screen to decide what's worth your time; underwrite to decide what's worth your money. The canonical deal fails a strict 1% screen, yet the full underwrite reveals a far more nuanced economic picture than "0.79%" could — which is exactly why you run the analysis, and exactly what the next guide's buy/pass decision is for.

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The bottom line

The 1% rule and the gross rent multiplier are excellent triage tools and terrible verdicts. Both use only rent and price and are two transformations of the same rent-to-price relationship, so they are not independent evidence. Both are also blind to taxes, vacancy, condition, and financing — much of what determines whether a deal works. The canonical rental sits below 1% (0.79%), and the screen can't tell you whether that thinness is a dealbreaker or acceptable — which is the whole lesson: screen to decide what deserves a full underwrite, then let the underwrite and the buy/pass decision — not the screen — make the call.

About the author

Matt Nunn is the founder of Builders Finance. He has spent two decades working with the financial side of real estate businesses, and started Builders Finance to give short-term-rental operators the financial systems, frameworks, and plain-language education that most hosting advice skips over. Builders Finance publishes educational content for STR owners; it is not legal, tax, or investment advice, treatment depends on your facts and circumstances, and it is not a substitute for guidance from your own qualified professionals.

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This resource provides general educational information and is not individualized investment advice. Screening ratios are rough triage tools; verify every deal with a full underwrite for your own situation.

Primary sources / provenance: BFC Deal Analysis P01 (underwrite the property you're buying) and P11 (a deal that only pencils if everything goes right hasn't penciled); the Phase-2 LTR metric definitions (GRM = price ÷ gross annual rent; rent-to-value / 1% rule = monthly rent ÷ price — both screens, not underwrites). Screen inputs are property-specific and verified per deal, not evergreen.