Rental Property Cash Flow Calculator

How to Use This Cash Flow Calculator

Enter your annual gross rental income, annual operating expenses, and monthly mortgage payment (principal and interest). The calculator shows both your annual and monthly cash flow. Positive cash flow means money in your pocket each month. Negative cash flow means you're supplementing the property from other income.

Cash Flow Formula

Cash flow is the money left over after paying all expenses including your mortgage. Positive cash flow means the property is generating spendable income. Unlike NOI, cash flow includes debt service.

Worked Example

Your rental collects $3,000/month ($36,000/year). Annual operating expenses are $13,200. Monthly mortgage P&I is $1,400 ($16,800/year). Cash Flow = $36,000 - $13,200 - $16,800 = $6,000/year or $500/month. You pocket $500 each month after all expenses and the mortgage are paid.

What is a Good Cash Flow?

Most investors target at least $100-200/month per unit in cash flow. More conservative investors aim for $200-300+/unit. The '$100/door' rule is common in rental property investing as a minimum threshold. However, some investors in appreciating markets accept lower (or even slightly negative) cash flow because they expect property value gains to compensate. The key is that your investment thesis should be explicit about whether you're investing for cash flow, appreciation, or both.

Factors That Affect Cash Flow

Cash flow depends on three things: how much rent you collect, how much you spend to operate the property, and how much your mortgage costs. You can improve cash flow by increasing rents, decreasing expenses, or refinancing to a lower rate. Vacancy is a major cash flow killer: even one month vacant per year reduces annual cash flow by 8%. Unexpected major repairs (HVAC, roof, plumbing) can wipe out months of positive cash flow, which is why maintaining a reserve fund is essential.