Cap Rate vs Cash-on-Cash Return: Which Matters More?

Cap rate and cash-on-cash return are the two metrics every rental investor learns first — and the two that get confused most often. They measure different things, and using the wrong one will make a deal look better (or worse) than it really is.

Here's the short answer, then the math, then how to decide which to lean on.

The 30-second version

• Cap rate tells you how the property performs, ignoring how you paid for it.
• Cash-on-cash return tells you how the cash you put in performs, after the mortgage.
• Use cap rate to compare properties. Use cash-on-cash to compare deals you'd actually do.

How to calculate cap rate

Net Operating Income (NOI) is rent minus operating expenses — taxes, insurance, property management, repairs, vacancy reserve. It excludes the mortgage and capital expenditures.

Example: a $300,000 duplex with $30,000 annual rent and $12,000 of operating expenses has $18,000 NOI. Cap rate = 18,000 ÷ 300,000 = 6.0%.

How to calculate cash-on-cash return

Cash flow is NOI minus the mortgage payment. Cash invested is your down payment plus closing costs and any rehab.

Same duplex, 25% down ($75,000) plus $5,000 closing = $80,000 invested. Mortgage on $225,000 at 7% over 30 years ≈ $17,964/yr. Cash flow = 18,000 − 17,964 = $36. CoC = 36 ÷ 80,000 = 0.05%.

When to use which

Use cap rate when…

• Comparing properties in the same market on apples-to-apples terms.
• Pricing a property (cap rate × NOI ≈ value, in commercial deals).
• Talking to brokers — it's the standard listing metric.

Use cash-on-cash when…

• Deciding whether you should buy this specific deal.
• Comparing leveraged real estate to other places you could put cash (index funds, REITs, a HYSA).
• Stress-testing financing scenarios — different down payments change CoC dramatically.

Common mistakes

1. Putting the mortgage in NOI. Don't. NOI is unlevered by definition.
2. Forgetting vacancy and capex reserves. Most investors under-budget these by 5–10% of rent each.
3. Comparing your cap rate to a different market's cap rate. A 6% cap in Cleveland is not the same risk profile as a 6% cap in Austin.

What to track once you own the property

Both metrics drift the moment you close. Rents change, expenses creep, refinances reset the cash basis. Tracking actual NOI and cash flow each month is the only way to know whether the deal is still the deal you underwrote.

That's the whole reason we built Havyn's portfolio dashboard — so cap rate, cash-on-cash, NOI, and DSCR update automatically as bank transactions and owner statements come in.