How to calculate GRM (with a 2-minute market screening workflow)
GRM = Purchase price ÷ Annual gross rent. A $300,000 property renting at $2,200/month ($26,400/year) has a GRM of 11.4. Lower GRM means cheaper per dollar of rent. The calculation takes 3 seconds per property, which is the entire point: speed, not precision.
GRM is the metric you calculate when you do not have time to calculate the metric you actually want (cap rate). It trades accuracy for speed by ignoring expenses entirely. That sounds like a flaw, and it is, but it is a deliberate one. When you are scanning a list of 50 properties, you need a fast filter to find the 5 worth analyzing. GRM is that filter.
The formula
Two inputs. Both available on every listing. No expense data needed. That is it.
Worked example
| Property | Price | Monthly rent | Annual rent | GRM |
|---|---|---|---|---|
| Duplex in Memphis | $180,000 | $2,400 | $28,800 | 6.3 |
| SFR in Indianapolis | $250,000 | $1,900 | $22,800 | 11.0 |
| Townhome in Charlotte | $340,000 | $2,100 | $25,200 | 13.5 |
| SFR in Austin | $475,000 | $2,800 | $33,600 | 14.1 |
The Memphis duplex has the lowest GRM (6.3), meaning you pay the least per dollar of gross rent. But that does not automatically make it the best deal. The expenses in Memphis might be higher, the vacancy might be longer, and the appreciation might be slower. GRM starts the conversation. It does not finish it.
The 10-minute screening workflow
Here is how to use GRM practically when you are looking at a batch of properties:
- Step 1: Know the local GRM range. Ask a property manager, check recent sales, or look at our GRM benchmark guide for city-by-city ranges.
- Step 2: Calculate GRM for each listing. Price ÷ (monthly rent x 12). Three seconds each. You can do 20 properties in two minutes.
- Step 3: Flag everything at or below the local average. In Indianapolis, anything under 8 gets a closer look. In Austin, anything under 13.
- Step 4: Run cap rate on the flagged properties. This is where you add expense data and get the real yield.
You just went from 50 listings to 8 to 10 shortlisted properties in under 15 minutes. That is the value of GRM.
The critical limitation
GRM ignores expenses. All of them. Two properties with identical GRMs can have completely different cap rates if their expense profiles differ:
| Property X | Property Y | |
|---|---|---|
| Price | $250,000 | $250,000 |
| Annual rent | $30,000 | $30,000 |
| GRM | 8.3 | 8.3 |
| Expense ratio | 35% | 55% |
| NOI | $19,500 | $13,500 |
| Cap rate | 7.8% | 5.4% |
Same GRM. Very different cap rates. Property Y might be in a high-tax state with expensive insurance, or it might need a property manager while Property X is owner-managed. GRM cannot distinguish. That is why it is a screening tool, not a decision tool.
GRM monthly shortcut
Some investors use monthly rent instead of annual:
A $300,000 property at $2,200/month = 136 monthly GRM. This is the same ratio, just expressed differently. The 1% rule (monthly rent should equal 1% of price) translates to a monthly GRM of 100. Any monthly GRM below 100 means the property clears the 1% rule.
Frequently asked questions
How do you calculate GRM?
GRM = Purchase price divided by annual gross rent. For a $250,000 property renting at $1,800/month ($21,600/year), the GRM is 250,000 / 21,600 = 11.6.
What is a good GRM?
In cash-flow markets (Memphis, Cleveland), 4 to 8. In balanced markets (Tampa, Charlotte), 8 to 12. In appreciation markets (Austin, Denver), 12 to 17. Lower is generally better, but compare within the same market.
Is lower GRM always better?
Not always. A very low GRM can signal a problem property, an inflated rent projection, or a tough neighborhood where the low price reflects low demand. Always verify rent and condition before trusting a low GRM.
Does GRM account for expenses?
No. GRM uses gross rent only, ignoring all operating expenses. Two properties with the same GRM can have very different cap rates and cash flows depending on their expense profiles.
How is GRM related to the 1% rule?
The 1% rule says monthly rent should equal at least 1% of purchase price. That translates to a monthly GRM of 100 or an annual GRM of about 8.3. Properties that clear the 1% rule have an annual GRM below 8.3.