Rental Property Cash Flow: How to Calculate It + Free Calculator

A rental property can collect plenty of rent and still make surprisingly little money.

Mortgage payments leave your account. Insurance gets paid. Management takes its cut. Then a boiler decides it has had enough.

That is why rental property cash flow is one of the most useful numbers a landlord can track.

It answers one simple question:

After the money comes in and the property bills go out, how much cash is actually left?

Here is how to calculate it.

What Is Rental Property Cash Flow?

Rental property cash flow is the money left after subtracting the property's expenses from its income over a particular period.

Most landlords track it monthly:

Rental Income − Property Expenses = Monthly Cash Flow

If income is higher than expenses, you have positive cash flow.

If expenses are higher than income, you have negative cash flow.

Simple formula. The important part is making sure you're counting the right numbers.

Rental Property Cash Flow Formula

Suppose a property generates:

Monthly rental income: $2,500 Monthly property expenses: $1,900

Your cash flow is:

$2,500 − $1,900 = +$600

So the property generates $600 in positive monthly cash flow.

But what belongs in that $1,900?

What Should You Include?

Rental Income

Start with all regular income generated by the property.

This might include:

• rent;
• parking;
• storage;
• garage income;
• other recurring property income.

If rent is $2,000 and parking brings in another $100:

Total monthly income = $2,100

Mortgage Payments

If the property is financed, include the monthly mortgage payment when you want to understand the actual cash moving in and out of your pocket.

For example:

Mortgage payment: $950/month

Ignoring it could make your property look much more profitable than it feels in reality.

Regular Property Costs

Include recurring costs that actually apply to your property, such as:

• property management;
• insurance;
• taxes;
• service charges;
• HOA or building fees;
• utilities you pay;
• routine maintenance.

Annual costs can be converted into a monthly equivalent when estimating cash flow.

For example:

Annual insurance: $1,200

$1,200 ÷ 12 = $100/month

Unexpected Expenses

This is where tidy projections often meet reality.

A property may suddenly need:

• a new boiler;
• plumbing repairs;
• an appliance replacement;
• an emergency electrician;
• roof or building work.

These costs can transform a profitable month into a negative one.

That does not necessarily mean the property is a bad investment. It means looking at cash flow over time matters.

Worked Rental Property Cash Flow Example

Imagine a rental property with:

Income

Rent: $2,400 Parking: $100

Total monthly income: $2,500

Expenses

Mortgage: $1,050 Management: $180 Insurance: $90 Taxes / service charges: $170 Maintenance: $100 Utilities: $60

Total monthly expenses: $1,650

Now calculate:

$2,500 − $1,650 = +$850

Your monthly cash flow is:

+$850

Pretty healthy.

But then the boiler breaks.

Repair cost:

$1,400

That month's result becomes:

$850 − $1,400 = -$550

So one month shows:

-$550 cash flow

The property did not suddenly become terrible. It simply had an expensive month.

That is why a single calculation tells only part of the story.

How Vacancy Changes Cash Flow

Rent does not necessarily arrive every month forever.

A tenant may leave. The property may need repairs before the next tenant moves in. Finding a replacement can take time.

Suppose a property normally rents for:

$2,000/month

At full occupancy:

$2,000 × 12 = $24,000/year

But if it sits empty for one month:

Actual annual rental income = $22,000

Average monthly rent across the year becomes roughly:

$1,833

That can make a meaningful difference to your real return.

If you're evaluating a potential investment, allowing for some vacancy can make your estimate more realistic.

If you already own the property, tracking what actually happened month by month gives you an even clearer picture.

Positive vs Negative Cash Flow

Positive Cash Flow

Income is higher than expenses.

For example:

Income: $2,500 Expenses: $2,000

Cash flow: +$500

The property put an additional $500 in your pocket that month.

Negative Cash Flow

Expenses are higher than income.

For example:

Income: $2,500 Expenses: $2,800

Cash flow: -$300

You had to put an additional $300 into the property.

One negative month is not necessarily alarming.

Repeated negative cash flow is a different story.

That is why the trend matters more than one isolated number.

Why Track Cash Flow Month by Month?

Imagine this history:

April looks ugly.

But perhaps April included a $1,500 emergency repair.

When you can see the full history, the result makes sense.

Month-by-month tracking can help you spot:

• rising expenses;
• unusually expensive repairs;
• changes in rent;
• periods of vacancy;
• properties that consistently outperform others;
• properties quietly consuming more cash than expected.

That becomes especially useful once you own more than one rental property.

How to Calculate Rental Property Cash Flow in 5 Steps

You can keep the process very simple.

Step 1: Add your income

Include rent and any other recurring property income.

Step 2: Add regular expenses

Mortgage, insurance, management, taxes, service charges, utilities and other recurring costs.

Step 3: Add unexpected expenses

Include repairs and one-off costs in the month they happen.

Step 4: Account for vacancy

Use actual rental income when tracking an existing property, or a sensible vacancy assumption when evaluating one.

Step 5: Subtract expenses from income

Total Income − Total Expenses = Cash Flow

That's your number.

Use a Free Rental Property Cash Flow Calculator

You do not need to build a spreadsheet just to run the calculation.

Propertira's free Rental Property Cash Flow Calculator lets you enter your income and property costs and see your estimated monthly cash flow.

You can use it to test questions such as:

• What happens if rent increases?
• How much is the mortgage affecting cash flow?
• What happens after management fees?
• How much can the property absorb in regular costs?
• How much money is actually left each month?

→ Try the Free Cash Flow Calculator

No bank connection is required.

A Calculator Shows Today. Tracking Shows the Story.

A calculator is useful for answering:

What does this property look like right now?

But rental properties change.

Rent changes.

Costs increase.

Repairs happen.

Vacancy happens.

Mortgage payments change.

And once you own several properties, it becomes harder to remember which one is genuinely carrying the portfolio and which one merely looks profitable on paper.

That is where ongoing tracking becomes useful.

Track Rental Property Cash Flow With Propertira

Propertira gives landlords and property investors a simple place to track the financial side of their rental portfolio.

You can keep track of:

• rental income;
• mortgage payments;
• regular property costs;
• unexpected expenses;
• monthly cash flow;
• individual property performance;
• portfolio comparisons.

No direct bank connection is required.

No giant property-management system.

No spreadsheet maze.

Want to track the number month after month? Try Propertira.

→ Start tracking your properties for free