Real Estate Rules of Thumb, Ranked by How Much You Can Trust Them

The 1%, 2%, 50%, 70% and 5% rules exist to save time, not to make decisions. Here is what each is actually worth.

7 rules

Ranked by how much weight each one can actually carry.

The ranking

Rule	What it screens	Trust	Where it breaks
The 50% rule	Operating expenses ≈ half of gross rent	High	New construction and tenant-paid utilities run lower; high-tax and older stock run higher.
The 70% rule	Maximum offer for a flip or BRRRR	High, if you adjust the percentage	Too tight under $100k ARV, too loose above $600k, and wrong for BRRRR without adjustment.
1% of value per year for maintenance	Ongoing physical costs	Medium-high	Newer properties run less; anything pre-1970 runs more. Does not replace a CapEx budget.
The 1% rule	Rent relative to price	Medium	Ignores expenses entirely. Nearly extinct in appreciation markets, which does not make those markets bad.
The 5% rule (rent vs buy)	Whether to rent or own a home	Medium	A personal-finance rule, not an investment rule. Useful framing, poor precision.
$100 per door per month	Minimum acceptable cash flow	Low	Ignores capital invested entirely. $100/door on $80k invested is a different deal from $100/door on $20k.
The 2% rule	Rent relative to price, aggressively	Low	Where it is still met it usually signals risk. As a filter it excludes nearly everything.

Why the 50% rule outranks the 1% rule

Both are one-line approximations, but they approximate different things — and one of those things is far more stable than the other.

Operating costs are physical. Roofs cost what they cost, insurance prices rebuild cost, taxes are a percentage of assessment, and management is a percentage of rent. Those relationships move slowly and travel reasonably well between markets. Price-to-rent ratios are set by capital markets and local demand, and they moved enormously between 2012 and 2024. A rule pinned to the second is a rule pinned to a market condition; a rule pinned to the first is closer to a physical constant.

The two-rule screen worth actually using

Combine them. If rent is about 1% of price monthly, and expenses run about 50% of rent, then NOI ≈ 6% of price — roughly a 6% cap rate before financing. That single chain converts a listing headline into an estimated cap rate with no data beyond price and rent, and it is accurate enough to rank a list.

The two rules people misuse most

$100 per door

The problem is that it has no denominator. $100 a month per unit is an excellent return on $15,000 invested and a poor one on $90,000. It also creates a perverse incentive: the easiest way to hit $100 a door is to put more money down, which improves the metric while lowering your actual return. Use cash-on-cash return instead — same information, with the denominator attached. See also why per-door benchmarks mislead.

The 1% of value maintenance rule

This one is better than its reputation, with an important caveat: 1% of property value per year covers maintenance and capital costs combined, not maintenance alone. On a $240,000 property that is $2,400 a year — and component-based CapEx budgeting alone comes to roughly $4,000. Treat 1% as a floor for older stock and 2% as the realistic figure once genuine capital replacement is included.

How to use rules of thumb without getting hurt

Do	Don’t
Use them to rank a list of 40 listings	Use them to decide on one
Use two that check different things — one income, one expense	Rely on a single ratio
Adjust the constant to your market and price band	Treat 70%, 50% or 1% as fixed laws
Let them tell you what to analyse next	Let them tell you what to buy
Notice when a property fails one badly — that is signal	Reject an entire market because it fails the 1% rule

The failure mode nobody talks about

Rules of thumb produce false negatives as often as false positives. An investor who mechanically applies the 1% rule rules out every appreciation market in the country — including the ones that produced the best total returns of the last decade. Screens are for triage. The deal is decided by NOI, DSCR, cash-on-cash and IRR — which is about four minutes of work in the free calculator, for the handful of properties that survive the screen.

Frequently asked questions

Which real estate rule of thumb is most reliable?

The 50% rule, which estimates operating expenses at about half of gross rent. Operating costs are driven by physical and tax realities that move slowly and translate reasonably well between markets, whereas price-to-rent rules like the 1% and 2% rules are pinned to market conditions that have shifted substantially.

Is the 1% rule outdated?

As a hard filter, largely yes — properties meeting it have become scarce in many markets as prices outpaced rents. As a relative comparison within a single submarket it still ranks listings usefully. Its permanent weakness is that it ignores operating expenses entirely.

What is the 5% rule in real estate?

A rent-versus-buy heuristic: roughly 5% of a property's value per year, split between maintenance, property taxes and the cost of capital, approximates the unrecoverable annual cost of owning. Divided by twelve it gives a monthly figure to compare against renting. It is a personal-housing framework rather than an investment screen.

Should I use rules of thumb at all?

Yes, for triage. They let you rank many properties quickly and spot outliers worth investigating. They should never be the basis for a purchase decision, because every one of them compresses away the specific information — taxes, condition, turnover, financing — that separates two properties with identical headline ratios.