How to Calculate Rental Property Cash Flow

Introduction

Rental property cash flow is one of the most important numbers investors evaluate when considering a buy-and-hold property.

However, calculating cash flow requires more than subtracting a mortgage payment from monthly rent.

A useful analysis should account for rental income, vacancy, operating expenses, debt service and other applicable cash expenses.

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What Is Rental Property Cash Flow?

Rental property cash flow represents the amount of money remaining after the income and expenses included in your analysis have been accounted for.

The exact formula can vary depending on the investor’s methodology.

A useful framework is:

Effective Rental Income − Operating Expenses = NOI

Then:

NOI − Debt Service − Other Applicable Cash Expenses = Cash Flow

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Step 1: Calculate Rental Income

Start with scheduled rental income.

For example:

$2,500 monthly rent × 12 months = $30,000 annual scheduled rent.

Then account for vacancy and collection loss.

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Step 2: Account for Vacancy

A property that is vacant for part of the year will not produce its full scheduled rental income.

Consider:

• Historical vacancy
• Local rental demand
• Tenant turnover
• Unit condition
• Leasing time

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Step 3: Calculate Operating Expenses

Consider:

• Taxes
• Insurance
• Management
• Maintenance
• Repairs
• Owner-paid utilities
• HOA
• Leasing expenses
• Other recurring expenses

Step 4: Calculate NOI

For example:

Annual effective income: $28,500

Operating expenses: $11,000

NOI:

$28,500 − $11,000 = $17,500

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Step 5: Subtract Debt Service

If annual debt service is $12,000:

$17,500 − $12,000 = $5,500

Projected cash flow is therefore $5,500 before other applicable cash expenses.

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What About CapEx?

Capital expenditures should not simply disappear from the analysis.

Roof replacement, HVAC replacement and other major components can create substantial future expenses.

You can model these separately as a reserve or use another methodology appropriate to your analysis.

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Example

Item	Annual Amount
Effective rental income	$28,500
Operating expenses	-$11,000
NOI	$17,500
Debt service	-$12,000
Projected cash flow	$5,500

This is only an example. Actual investment analysis should use property-specific assumptions.

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Common Cash Flow Mistakes

Avoid:

• Using gross rent instead of effective income
• Ignoring vacancy
• Underestimating expenses
• Forgetting management
• Ignoring CapEx
• Using unrealistic financing assumptions
• Assuming future rent increases are guaranteed

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Use a Rental Property Calculator

InvestingTE’s free rental-property calculator is designed for initial cash-flow and purchase-price analysis.

The paid Rental Property Investment Calculator provides a broader analysis that includes cash flow and multiple investment metrics.

Analyze Your Rental Property Cash Flow