The 1% rule is a quick, back-of-the-envelope screening tool used by rental property investors: if a property's expected monthly rent is at least 1% of its total purchase price (including any immediate repair costs), it's generally considered worth a closer look for cash flow potential. If monthly rent falls well short of that 1% mark, the deal is more likely to be a weak cash-flow candidate, though it isn't automatically disqualified — it just needs a more careful look before moving forward.
The math behind the rule is deliberately simple: Monthly Rent ÷ Purchase Price × 100 = Rule Percentage. If the result is 1% or higher, the property clears the rule. You can also flip the formula around to find the "target rent" for a given price, or the "maximum price" for a given rent: Purchase Price × 0.01 = Minimum monthly rent to hit 1%, or Monthly Rent ÷ 0.01 = Maximum purchase price to hit 1%.
Take an illustrative property listed at $200,000. To satisfy the 1% rule, it would need to rent for at least $200,000 × 0.01 = $2,000 per month. If comparable rentals in the area are only fetching $1,600 a month, the property fails the rule by a meaningful margin ($1,600 is 0.8% of price, not 1%) — a signal to dig deeper into the numbers or negotiate the price down before assuming it will cash flow well. If the same property could realistically rent for $2,100 a month, it clears the rule, but only narrowly (about 5% above the $2,000 threshold) and is worth running through a full cash flow calculation next.
The 1% rule is a widely used investor rule of thumb. It is not a regulated standard, it does not come from a single study or official source, and it carries no guarantee. Investors scanning many listings use it because it needs only two numbers — price and rent — that are usually visible at a glance, with no need to know financing terms, taxes, or insurance costs up front. Its simplicity is both its appeal and its biggest limit.
The 1% rule deliberately ignores almost everything that actually determines whether a property makes money: financing terms and interest rate, property taxes, insurance costs, HOA dues, the age and condition of major systems, local vacancy rates, and property management costs. Two properties that both hit exactly 1% can have completely different real cash flow once those factors are accounted for — one with low property taxes and a low interest rate might cash flow well, while the other with high taxes, an aging roof, and a higher rate might not cash flow at all. The rule is a filter for where to spend your time, not a substitute for underwriting the specific numbers on a specific property.
The 1% rule is far easier to hit in lower-priced markets with modest home values and correspondingly modest rents than in expensive coastal or high-demand metro markets, where home prices have historically outpaced rent growth. In many of those higher-priced markets, very few properties clear 1% even when they're otherwise excellent long-term investments once appreciation, equity growth, and tax benefits are factored in. This is one of the rule's most important limitations: applied rigidly, it can cause an investor to walk away from strong markets entirely, or to overweight cheaper markets that may carry other risks (slower appreciation, weaker tenant demand, higher relative maintenance costs on older housing stock).
Because the 1% rule only looks at rent relative to purchase price, it says nothing about a property's potential for appreciation, or about the equity an owner builds over time as the mortgage principal is paid down. An investor buying primarily for long-term appreciation in a strong, high-demand market may knowingly accept a property that fails the 1% rule, because they're underwriting for total return over many years rather than for maximum monthly cash flow today. Neither approach is universally "right" — they're different strategies that call for different screening tools, and the 1% rule was built for the cash-flow-first strategy specifically.
Treat the 1% rule as a first-pass filter to decide which properties are worth 10 more minutes of your time, not as a final answer on whether to buy. A property that passes deserves a full cash flow analysis with your actual mortgage quote, current property tax assessment, real insurance quote, and a realistic vacancy and maintenance reserve. A property that fails isn't necessarily a bad investment — it may still make sense for an appreciation-focused strategy, or it may become viable at a lower negotiated price. Use the rule to prioritize your research time, then verify everything that actually matters with real numbers before making an offer.
If a property passes the 1% rule, the responsible next step is to run it through this site's full cash flow calculator using your actual mortgage payment, tax, insurance, and expense figures — not the rough estimate the 1% rule provides. That fuller calculation accounts for vacancy and maintenance reserves, management costs, and your real financing terms, giving you a far more reliable picture of what the property will actually put in your pocket each month.