A seller names a price. Your gut says it's too high. But how do you know what number actually works for you?
This is one of the most practical skills in real estate investing: reverse engineering your maximum purchase price from the income the property produces. Instead of reacting to what a seller is asking, you build your offer from the bottom up — starting with what the property can realistically earn and working backward to what you can afford to pay.
Here's how to do it step by step.
Step 1: Start With Stabilized Rent Roll
Before you can price anything, you need to know what the property should be generating — not what it is generating today.
If you're looking at a value-add deal where some units are below market, don't anchor to current rents. Calculate the stabilized rent roll: what all units would rent for at market rate once leases turn over or get bumped.
For example, if a 9-unit property has a current rent roll of $13,410/month but 4 units are significantly under market, a realistic stabilized rent roll might be closer to $18,000/month. That's the number you underwrite to.
Be honest with yourself here. Lease-up takes time, and problem tenants can delay it further. Add a buffer — most experienced investors underwrite to 90–95% of stabilized rent (i.e., 5–10% vacancy).
At $18,000/month and 5% vacancy: Effective Gross Income = $18,000 × 0.95 × 12 = $205,200/year
Step 2: Calculate Net Operating Income (NOI)
NOI is your gross income minus operating expenses — everything except debt service.
Common operating expenses:
- Insurance (typically $3,000–$8,000/year for a small multifamily)
- Property taxes (check the local mill rate; 1–1.5% of assessed value is common)
- Property management (8–10% of collected rent if outsourced)
- Maintenance and repairs (budget 10–15% of gross rents annually for older properties)
- CapEx reserves (another 5–10% depending on property age)
- Vacancy (already accounted for above)
- Utilities (if you cover water/trash/etc.)
A rough rule: for stabilized residential multifamily, total operating expenses often run 40–50% of gross income (the "expense ratio"). For older or larger properties, skew toward 50%+.
Using the example above:
- Effective Gross Income: $205,200
- Operating expenses at 45%: ~$92,340
- NOI: $112,860/year
Step 3: Pick Your Target Cap Rate
The cap rate (capitalization rate) is your unlevered return — what you'd earn if you bought the property in cash.
Cap Rate = NOI ÷ Purchase Price
To reverse engineer your purchase price, flip it:
Max Purchase Price = NOI ÷ Target Cap Rate
What cap rate should you target? That depends on:
- Market — a 5% cap might be aggressive in a hot coastal market and generous in the Midwest
- Asset quality — Class A buildings trade at lower cap rates than Class C
- Your return requirements — if you need to hit 8% cash-on-cash with leverage, work backward from there
For a B-class multifamily in a moderate market, a 7–8% cap rate is a reasonable target that leaves room for a real return once debt service comes out.
At 7.5% cap: Max Purchase Price = $112,860 ÷ 0.075 = ~$1.505M
At 7% cap: Max Purchase Price = $112,860 ÷ 0.07 = ~$1.61M
That's how you get to your number — not by splitting the difference between ask and a gut feel.
Step 4: Sanity Check with Cash-on-Cash Return
Cap rate is a useful shorthand, but most investors buy with debt. So also run the cash-on-cash math (your actual annual cash flow divided by out-of-pocket cash invested).
Back of the envelope:
- Purchase: $1.5M at 20% down = $300K equity, $1.2M loan
- At 7% interest, 30-year: ~$7,980/month in debt service = $95,760/year
- Annual cash flow: NOI ($112,860) − Debt Service ($95,760) = $17,100/year
- Cash-on-cash: $17,100 ÷ $300,000 = 5.7%
Is that enough for you? That's a personal decision — but at least you're making it with real numbers.
If the listed price of $2.3M pencils to a 2% cap rate and negative cash flow, you know to walk or make a dramatically lower offer.
Key Takeaways
- Anchor to stabilized rent roll, not current actuals — especially on value-add deals
- NOI is the engine: build it carefully with realistic vacancy, expenses, and reserves
- Cap rate is your pricing lever: decide your required return first, then solve for price
- Cross-check with cash-on-cash: real returns happen after financing, not before
- The seller's ask is just a starting point — your analysis tells you what to actually offer
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