Cap rate explained properly is less about the formula, which takes ten seconds to learn, and more about why the same property's cap rate can shift meaningfully without a single thing about the property itself changing.
What's Inside
Cap rate explained at the formula level takes about ten seconds: net operating income divided by property value. What actually matters for making good decisions is understanding why that number moves the way it does, and what it's really telling you when it does.
Quick honesty note
This is education, not financial advice. Current Treasury yields and cap rate spreads change over time, and this is genuinely time-sensitive content, market conditions shift within a quarter, not a year.
The Short Answer
The Formula, Briefly
Cap rate equals net operating income divided by property value or purchase price. It's covered at the introductory level, including sector-specific ranges, in commercial real estate investing for beginners and multifamily real estate investing guide. This guide picks up from there.
Compression and Expansion, What the Terms Actually Mean
Cap rate compression happens when demand for real estate assets exceeds the supply of investable properties, pushing prices up and yields down, cap rates fall. Cap rate expansion is the reverse: prices fall relative to income, and cap rates rise.
When a market commentator says "cap rates have compressed," they mean asset prices have risen relative to income, not that returns have improved. This is genuinely the most commonly confused part of the concept, a falling cap rate sounds like good news the way a falling bond yield might, but it generally means the asset has gotten more expensive, not cheaper.
Why Cap Rate Moves With Interest Rates Even When Income Doesn't
Cap rate functions as the risk-free rate, generally the 10-year Treasury yield, plus a risk premium for the specific illiquidity, vacancy, and management risk of owning real estate. Historically, that spread has run somewhere in the range of 150 to 400 basis points depending on asset class and market tier.
Same income, different discount rate
In a 5.0% Treasury environment, a 6.5% cap rate represents a 150 basis point spread over the risk-free rate. In a 2.0% Treasury environment, that same spread logic could price the identical property, with the identical income, at 3.5%. The income didn't change. The discount rate did. This is why cap rates compressed steadily as interest rates fell for much of the 2010s, and why they expanded rapidly as rates rose in 2022 and 2023.
As of recent readings, the spread between cap rates and Treasury yields has compressed to levels described as historically thin, near multi-decade tights in some market segments. A thinner spread means investors are being paid less additional yield for taking on real estate-specific risk relative to a government bond, worth knowing before assuming today's pricing reflects a normal, historically typical risk premium.
The Negative Leverage Trap
When borrowing costs more than the property yields
If you can borrow at roughly 6.5% and use that debt to buy a property yielding a 4% cap rate, you are paying more to rent the money than the building pays you to own it. This is negative leverage, and it means adding debt to the deal actively reduces your return rather than enhancing it, the opposite of how leverage is supposed to work. Before assuming debt automatically improves a deal's returns, compare your actual borrowing cost directly against the property's cap rate.
This is a genuinely important check, historically, investors could often achieve a meaningful positive spread, sometimes 200 or more basis points, between a property's cap rate and their cost of debt, a spread that has compressed considerably in recent years to a much thinner cushion. Leverage only helps your return when your cap rate exceeds your cost of debt; when it doesn't, you're better off with less leverage, not more.
Going-In Versus Exit Cap Rate
The going-in cap rate is observed: current NOI divided by the purchase price at acquisition, a known number reflecting what the market is actually paying for comparable income today. The exit cap rate is assumed: the cap rate you project will apply to future NOI when you eventually sell, and it is genuinely one of the single most influential assumptions in any multi-year underwriting model. A full percentage point of exit cap rate expansion can move a projected IRR by more than 700 basis points, a dramatic swing driven by one assumption nobody can actually know in advance.
A common underwriting convention starts from the known going-in cap rate and adds a cushion, sometimes as little as 25 basis points for a base case, with 50 to 150 basis points used as a genuine stress test, rather than assuming your exit cap rate will match or beat today's number. Presenting a single exit cap rate assumption with no sensitivity range hides exactly how much of a projected return depends on a number that is, by definition, a guess.
Common Mistakes (and How to Dodge Them)
- Treating a falling cap rate as automatically good news. Compression generally means the asset has gotten more expensive, not that returns have improved.
- Ignoring the spread over Treasuries. The absolute cap rate number matters less than the spread, which reflects the real risk premium you're being paid.
- Assuming leverage always improves returns. When your cost of debt exceeds the property's cap rate, adding leverage actively hurts your return.
- Underwriting a single, optimistic exit cap rate with no sensitivity check. A full point of exit cap expansion can move IRR by more than 700 basis points.
- Assuming today's tight spread environment is permanent. Spread levels move with the broader credit and interest rate cycle, not in one direction forever.
Frequently Asked Questions
What does cap rate compression actually mean?
It means asset prices have risen relative to income, causing the cap rate to fall. It describes price movement, not an improvement in the property's actual returns.
Why does cap rate move with interest rates?
Cap rate functions as the risk-free Treasury rate plus a risk premium for real estate-specific risk. When Treasury yields fall, the same spread can price an identical property at a lower cap rate, even though the property's income hasn't changed at all.
What is negative leverage in real estate?
It occurs when your cost of borrowing exceeds the property's cap rate, meaning you're paying more to finance the deal than the property yields. In this situation, adding debt actively reduces your return rather than enhancing it.
What is the difference between going-in and exit cap rate?
The going-in cap rate is observed, based on current NOI and the purchase price at acquisition. The exit cap rate is assumed, applied to projected future NOI at an eventual sale, and it is one of the most influential assumptions in a multi-year underwriting model.
How much does the exit cap rate assumption actually matter?
Significantly. A full percentage point of exit cap rate expansion can move a projected IRR by more than 700 basis points, which is why conservative underwriting typically assumes some expansion rather than assuming today's rate holds indefinitely.
What is a reasonable spread between cap rate and the 10-year Treasury?
Historically, this spread has run roughly 150 to 400 basis points depending on asset class and market tier, though it fluctuates with the broader interest rate and credit cycle and should be checked against current conditions.
The Number Is a Snapshot, Not a Verdict
Cap rate explained fully is less about memorizing a formula and more about reading what a specific number is actually telling you at a specific moment: how it relates to Treasury yields, whether leverage is helping or hurting your return, and how sensitive your projected return is to an exit cap rate assumption nobody can know in advance. Treat any single cap rate as a snapshot to interrogate, not a verdict to accept at face value.
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Keep learning: commercial real estate investing for beginners · multifamily real estate investing guide · how to calculate rental property ROI · how to read a commercial real estate pro forma.
Education only, not financial advice. Cap rate spreads, Treasury yields, and sector-specific ranges shift frequently with market conditions; figures here are illustrative and marked for verification where noted. Consult a commercial real estate or financial professional before underwriting a specific deal.
Written by
Nwaeze David
Nigerian digital entrepreneur, educator and author of three real estate books. He writes practical, honest guides for new investors, working realtors and Africans building back home from abroad.
