NOI vs. Cap Rate vs. Cash-on-Cash vs. IRR: Which Metric When
Ask five people in commercial real estate which metric matters most and you’ll get five different answers, because they’re usually solving five different problems. Net operating income, cap rate, cash-on-cash return, and IRR aren’t competing metrics. They answer different questions, at different points in a deal, for different audiences. Confuse them and you’ll either underwrite the wrong deal or misread a good one.
This page breaks down what each metric actually measures, when it’s the right tool, and where it falls apart if you lean on it alone.
Net Operating Income (NOI)
NOI is the property’s income before financing and before the owner’s personal tax situation enters the picture. It’s the foundation every other metric on this page is built from.
Formula: Gross rental income, plus other income like parking, laundry, or storage, minus vacancy and credit loss, minus operating expenses. Operating expenses include property taxes, insurance, utilities, repairs and maintenance, management fees, and reserves for turnover. NOI excludes debt service, capital expenditures, depreciation, and income taxes.
That exclusion is the whole point. NOI is meant to describe the asset, not the buyer. Two investors could buy the identical building, one with cash and one with 75% leverage, and the NOI is the same for both because financing hasn’t entered the calculation.
When to use it: Every time you underwrite a property, before you get anywhere near a purchase price or a loan term. Use it to compare the operating performance of two similar buildings, to spot an expense line that’s out of step with the market, or to check a seller’s pro forma against trailing twelve-month actuals.
Limitation: NOI tells you nothing about what you paid, how the deal is financed, or what you’ll walk away with. A building throwing off $500,000 in NOI could be a great deal at a $6,000,000 purchase price and a poor one at $10,000,000. NOI alone can’t tell you which.
Cap Rate
Formula: NOI divided by purchase price, or by current market value if you’re valuing a property you already own.
Cap rate answers a single question: what unlevered yield does this property generate on the total price paid, as if you bought it all cash? It’s a snapshot, calculated off one year of income, with no financing and no future growth built in.
When to use it: Cap rate is the fastest way to compare pricing across similar deals in a similar market, and it’s the standard language brokers and appraisers use to talk about value. A 5.5% cap rate multifamily deal in a given submarket tells you roughly where pricing sits relative to a 6.5% cap rate deal three blocks away, all else equal. It’s also the mechanism appraisers use in the income approach to valuation, where NOI divided by a market-derived cap rate produces an estimated value.
Limitation: Cap rate ignores financing entirely, so it can’t tell you what return you’ll actually earn on your equity. It also ignores everything that happens after year one: rent growth, lease rollover, capital needs, and how the market’s cap rate might move by the time you sell. A low cap rate today can still produce a strong return on a value-add deal with real NOI growth ahead of it, and a high cap rate can be a trap if the in-place income is about to fall off.
Cash-on-Cash Return
Formula: Annual pre-tax cash flow, which is NOI minus debt service, divided by total cash invested: down payment, closing costs, and any immediate capital improvements.
This is the first metric on this list that accounts for leverage, and it’s the one most individual investors actually feel in their bank account. It measures the return on the cash you put in, not the return on the total purchase price.
Run the numbers on a simple example. A property with $500,000 in NOI sells for $7,500,000, a 6.67% cap rate. Finance it at 65% loan-to-value with an interest-only loan at 6%: the loan is $4,875,000, annual debt service is $292,500, and cash flow after debt service is $207,500. Equity invested is $2,625,000. Cash-on-cash return is $207,500 divided by $2,625,000, or 7.9%, meaningfully higher than the 6.67% cap rate because the cost of debt sits below the cap rate. That gap is positive leverage: borrowed money is earning more than it costs, and the difference flows to the equity holder.
When to use it: Cash-on-cash is the right lens when you’re comparing financing structures on the same deal, or when an investor cares more about near-term income than long-term appreciation. It’s common in syndications and private placements because it maps directly to the distribution an investor actually receives each year.
Limitation: It’s still a single-period snapshot. Cash-on-cash in year one tells you nothing about year five, and it ignores what happens at sale entirely. A deal with a mediocre cash-on-cash return but a large value-add upside at exit can still be the better investment. It also doesn’t credit principal paydown, which is real equity building even though it never shows up as cash in hand.
Internal Rate of Return (IRR)
IRR is the annualized, time-weighted return across the entire hold period, incorporating every cash flow: the initial equity investment as an outflow, every year of operating cash flow, and the net proceeds from sale. Technically, it’s the discount rate at which the net present value of all those cash flows equals zero.
Unlike the other three metrics, IRR accounts for the time value of money and it’s the only one that captures the exit. Two deals can post identical five-year total returns but different IRRs if one pays cash flow steadily throughout the hold and the other back-loads everything into the sale. Money returned sooner is worth more, and IRR is built to reward that.
In practice, nobody solves IRR by hand. It’s an iterative calculation, run in Excel with the IRR or XIRR function, or inside a proper pro forma model.
When to use it: IRR is the right metric for judging a full investment decision over a defined hold period, especially on value-add or development deals where cash flow is irregular and a large share of the return comes from a projected sale. It’s the standard basis for comparing deals against each other on a total-return footing, and it’s what institutional investors and fund sponsors report to their LPs.
Limitation: IRR is only as good as its assumptions, and it carries more of them than any metric on this list: hold period, exit timing, exit cap rate, rent growth, and future expense growth. Move the exit cap rate assumption by half a point and the projected IRR can swing several points with it. IRR also carries a reinvestment-rate quirk, since it implicitly assumes interim cash flows get reinvested at that same IRR, which is rarely realistic, and it can behave oddly on deals with unconventional cash flow patterns, like a large capital call midway through the hold. Treat a projected IRR as a modeling output tied to specific assumptions, not a guarantee.
Side-by-Side Comparison
| Metric | What It Measures | When to Use It | Limitation |
|---|---|---|---|
| NOI | Property-level income before financing, capex, and taxes | Underwriting the asset itself; comparing operating performance across properties | Says nothing about price paid, financing, or investor return |
| Cap Rate | Unlevered yield on purchase price (NOI ÷ price) | Comparing pricing across similar deals; income-approach valuation | Ignores financing, future growth, and everything after year one |
| Cash-on-Cash | Levered return on actual equity invested in a given year | Comparing financing structures; investors prioritizing near-term income | Single-period snapshot; ignores exit and principal paydown |
| IRR | Annualized, time-weighted return across the full hold, including exit | Judging total return on value-add, development, or multi-year holds | Highly sensitive to exit cap rate and hold-period assumptions |
Putting Them Together
In a real underwriting workflow, you don’t pick one of these and ignore the rest. You use them in sequence.
- Build NOI first, from actual trailing income and a realistic expense schedule, not the seller’s optimistic pro forma.
- Check the cap rate against comparable sales to see whether the asking price is in line with the market.
- Layer in your actual financing terms and calculate cash-on-cash to see what the deal returns on your equity in year one.
- Model the full hold, including rent growth, capital needs, and a conservative exit cap rate, and run the IRR to judge the deal as a whole.
A deal can look attractive on one metric and mediocre on another, and that’s normal, not a red flag by itself. A stabilized, low-leverage core asset might show an unremarkable IRR next to a value-add deal, but a much steadier cash-on-cash return with far less execution risk. A ground-up development might show no cash-on-cash return at all for two years and still post the highest IRR in your pipeline. The metric you weight most should match what you’re actually trying to accomplish with the capital, not just which number happens to be highest.
If you want to run these numbers on a real deal instead of doing it by hand, ProForma School’s free CRE calculators include dedicated tools for cap rate, cash-on-cash return, and IRR, along with the NOI and debt service inputs that feed them. Plug in your own numbers and see how the four metrics move together instead of in isolation.