Cap Rate vs Cash-on-Cash vs Cash Flow: Which to Use When

Cash flow is net operating income minus debt service — money in the account after everything is paid. It is the most concrete of the three and the one you feel every month.

Its limitation is that it is an absolute number with no sense of scale. A property producing 200 a month is doing well on 30,000 invested and badly on 300,000. Cash flow tells you whether a property sustains itself; it cannot tell you whether it was worth buying.

Cap rate is net operating income divided by price, and it deliberately excludes financing. That exclusion is what makes it useful — it describes the building rather than the buyer, so two investors with different mortgages compute the same figure for the same asset.

Use it to compare properties against each other in the same market. Do not use it to judge your own return, because it says nothing about how you paid.

Cash-on-cash divides annual pre-tax cash flow by the cash you actually invested — down payment plus closing and renovation costs. Unlike cap rate, it fully reflects your financing.

It is the closest of the three to answering "what is this doing for me," but it is narrow. It excludes principal paydown, appreciation, depreciation, tax treatment and sale proceeds. Over a holding period those often matter more than the cash flow does.

Borrowing does two things at once: it reduces the cash you invest, and it adds a debt payment. The first raises cash-on-cash return, the second lowers it.

Which wins depends on whether the property out-earns the loan. When the cap rate is comfortably above the mortgage rate, leverage lifts cash-on-cash above the cap rate. When the mortgage rate is higher, leverage drags it below — and can turn a positive return negative.

The cap rate does not move at all, because it never included the mortgage. That is exactly why holding the two side by side is informative: the gap between them is a direct readout of what your financing is doing.

Healthy cap rate, poor cash-on-cash: the property is sound and the financing is expensive. Look at the loan, not the building.

Poor cap rate, healthy cash-on-cash: leverage is flattering a mediocre asset. This works while rates stay low and stops working at refinance.

Both poor: the price is wrong. No financing structure fixes a property bought too expensively.

Both healthy but cash flow near zero: usually a small deal where percentages look fine on a thin absolute base. Check that a single boiler replacement does not wipe out a year of returns.

None of the three account for capital expenditure. Roofs, boilers, windows and rewires arrive on a fifteen-year cycle rather than a monthly one, so they sit outside net operating income by convention.

This means every metric on this page is flattering to some degree. Investors typically handle it by reserving a percentage of rent separately for capex. A deal that only just works before that reserve does not really work.