Cash Flow Calculator

What Is Cash Flow in Real Estate?

Cash flow is the money a property puts in your pocket after it has paid for itself.

In its simplest form, cash flow is what remains from a property’s rental income once every operating expense and the mortgage have been paid. Rent and other income come in; property taxes, insurance, management, maintenance, utilities, and the loan payment go out. Whatever is left over each month — or each year — is your cash flow. When more comes in than goes out, the property is “cash-flow positive.” When the bills outrun the income, it is “cash-flow negative,” and the investment is costing you money to hold.

It helps to separate two ideas that are easy to confuse. Net operating income (NOI) is the property’s income after operating expenses but before the mortgage. Cash flow goes one step further and subtracts the debt service — the principal and interest you owe the lender. A building can produce healthy NOI and still deliver thin or negative cash flow if it carries a large or expensive loan.

Why Understanding Cash Flow Matters

Cash flow is the clearest measure of whether an investment actually works in the real world. Appreciation is a forecast — you only realize it when you sell, and markets don’t move on your schedule. Cash flow is what the asset produces while you own it. It is the difference between a property that quietly funds itself and one that drains your reserves every month.

Reliable cash flow is also what protects you when conditions tighten. A property with a comfortable cushion between its income and its obligations can absorb a vacancy, a rate increase, or an unexpected repair without forcing a sale at the wrong time. A deal that only “works” if everything goes perfectly leaves no room for the surprises that real estate inevitably delivers. This is why lenders lean so heavily on the debt-service coverage ratio (DSCR) — the ratio of NOI to debt service — as a gauge of how much breathing room a property really has.

Reading the Metrics Together

No single number tells the whole story, which is why the calculator above reports several side by side. Cap rate (NOI ÷ purchase price) shows the property’s unleveraged yield and lets you compare deals on equal footing, regardless of financing. DSCR (NOI ÷ debt service) measures the safety margin between income and the loan; most lenders want to see at least 1.20–1.25x. Cash-on-cash return (annual cash flow ÷ cash invested) tells you what your actual out-of-pocket dollars are earning each year. Read together, they reveal not just whether a property is profitable, but how much risk you are taking to earn that profit.

This calculator and the information above are provided for educational and illustrative purposes only and do not constitute investment, tax, or financial advice. All figures are estimates and depend on assumptions you provide. Real estate investments carry risk, including loss of principal, and past performance is no guarantee of future results. Consult a qualified financial, tax, and legal professional before making any investment decision.