The 1% rule, the 50% rule, and every other shortcut, graded
Rules of thumb are screens, not underwriting. What the 1% rule, 50% rule, GRM, and the 70% rule actually test, where each one breaks, and the order to apply them so you never buy a spreadsheet fantasy.
What are the real estate rules of thumb? They are one-line filters — the 1% rule (monthly rent ≥ 1% of price), the 50% rule (operating expenses ≈ half of rent), gross rent multiplier (price ÷ annual rent), and the flippers' 70% rule — that let you sort a hundred listings in an evening without opening a spreadsheet. Used correctly, they are a triage system: they tell you which deals deserve real underwriting. Used incorrectly — as a buying criterion — they are how investors end up owning properties that passed a slogan and failed arithmetic.
The 1% rule: a price-to-rent screen
A property passes if monthly rent is at least 1% of the all-in price — a $180,000 house renting for $1,800. The logic is crude but honest: at that ratio, with normal expenses and normal leverage, the deal roughly breaks even or better on cashflow. Below about 0.7%, no amount of operational skill makes the math work at standard financing.
What beginners miss is that the 1% rule is mostly a market screen. Coastal and high-appreciation metros routinely sit at 0.4–0.6% — those markets price appreciation, not cashflow — while midwest and southern secondary markets still surface 0.8–1.1% deals. If nothing in your market passes, the rule is telling you to either invest out of state, change strategies, or accept you're buying an appreciation asset and size your reserves accordingly.
The 50% rule: the one that keeps being true
Assume operating expenses — taxes, insurance, vacancy, repairs, capital expenditures, management, but not the mortgage — will consume half of gross rent over a long hold. New investors always think it's pessimistic, because in any single quiet year expenses might run 25%. Then year six delivers a roof, an HVAC, a turnover with two months vacant, and a reassessed tax bill, and the decade averages back toward half.
The 50% rule's real job is defensive: it makes the seller's pro forma prove itself. Any deal that only works at 30% expenses is a deal that only works until something breaks.
GRM and the rest of the toolkit
Gross rent multiplier — price ÷ gross annual rent — is the 1% rule wearing commercial clothes (a 1% deal is a GRM of ~8.3). Its virtue is speed across markets: GRM 6–8 markets are cashflow country, GRM 15–20 markets are appreciation bets. Its vice is that it ignores expenses entirely — property-tax-heavy Texas and low-tax Tennessee can share a GRM and produce very different NOI.
| What it tests | Where it breaks | |
|---|---|---|
| 1% rule | Price-to-rent — will this cashflow at normal leverage? | High-tax/high-insurance markets (passes but bleeds); appreciation markets (fails but performs) |
| 50% rule | Expense honesty — is the pro forma real? | Very high-rent units (expenses don't scale with rent) and brand-new builds (front-loaded quiet years) |
| GRM | Cross-market price of a rent dollar | Ignores expenses, taxes, and capex entirely — a ranking tool, never a verdict |
| 70% rule | Flip margin — max offer vs ARV and rehab | Thin-spread hot markets and heavy rehabs, where it's either too strict or not strict enough |
| DSCR ≥ 1.25 | Lender's version: does income cover debt with margin? | Nothing — it's the one rule that's also a real underwriting gate |
The order of operations
- 01Screen with GRM or the 1% ruleSort the market in minutes. Anything near or above 1% (or below your market's median GRM) goes in the maybe pile. You are discarding, not selecting.
- 02Stress with the 50% ruleTake real rent (comps, not listing claims), cut it in half, subtract the actual mortgage payment. Negative? Dead unless there's a value-add story. Positive? It has earned a spreadsheet.
- 03Underwrite for realLine-item expenses with actual tax and insurance quotes, honest capex reserves, and stress-tested rents — the full treatment in the deal analyzer. Rules of thumb got the deal to this table; they don't get a vote at it.
- 04Let the lender's math confirm yoursA DSCR check at stressed assumptions is the professional version of everything above. If your numbers and the lender's disagree, theirs are usually closer.
Run the survivors through the deal analyzer — it applies the full expense stack the shortcuts approximate.
Frequently asked questions
+What is the 1% rule in real estate?
A screening test: a rental passes if monthly rent equals at least 1% of the total purchase price (including upfront repairs) — $1,500 rent on a $150,000 all-in deal. At that ratio a conventionally financed property roughly breaks even or better after real expenses. It's a filter for deciding what to underwrite, not a substitute for underwriting.
+Is the 1% rule still realistic?
In most major metros, no — post-2020 price growth outran rents, and typical rent-to-price ratios sit at 0.5–0.8%. It still works as a relative screen (the best deals in any market are the ones closest to it) and as a market-selection signal: the markets where it passes are the markets where cashflow strategies still function.
+What is the 50% rule for rental property?
Assume operating expenses — taxes, insurance, vacancy, repairs, capital expenditures, and management, but not the mortgage — will average about half of gross rent over a long hold. Take half the rent, subtract your mortgage payment, and what remains is a fast, honest cashflow estimate that pro formas rarely survive.
+What is a good gross rent multiplier (GRM)?
Price divided by gross annual rent; lower is cheaper. Roughly: 6–8 signals a strong cashflow market, 9–12 moderate, 15+ an appreciation market. GRM ignores expenses, so it compares markets and screens listings — pairing it with the 50% rule covers the blind spot.
+Can I buy a property based on the 1% rule alone?
No. The rules of thumb share one purpose: deciding which deals deserve full analysis. A passing deal can still fail on real taxes, insurance, deferred maintenance, or neighborhood trajectory; a failing deal can still win on value-add or appreciation. Screen with the rules, decide with underwriting.
The full treatment the survivors get: how to analyze a rental property. The flip-side shortcut: the 70% rule. Why the boring deal that merely passes is the right first one: your first deal should be boring.