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🏘️Rental Property Investment Calculator

Analyze a rental property's income, expenses, cash flow, and cash-on-cash return. Includes the 1% rule, 50% rule, and full expense breakdown.

Your Numbers

Property

Monthly Income

Fixed Monthly Expenses

Variable Expenses (% of monthly income)

Cash Invested

Your Results

Monthly Cash Flow
-$100
-$1,200/yr
Cash on Cash Return
-2.4%
1% Rule
1%
Passes -- monthly rent is at least 1% of purchase price
Total Monthly Income
$2,000
Total Expenses (incl. mortgage)
$2,100
50% Rule (quick estimate)
50% of income (est. operating costs)$1,000
Mortgage$1,200
Projected cash flow-$200
Variable Expense Breakdown
Vacancy (5%)$100
Repairs (5%)$100
Capital expenses (10%)$200
Property management (10%)$200
Total Cash Invested
$49,000
Annual Cash Flow
-$1,200

What Is Rental Property Investment?

A rental property investment calculator estimates whether a specific property is likely to generate positive cash flow, what return it delivers on the cash you put in, and how it holds up under a full expense breakdown that most back-of-napkin estimates miss. The quick rules of thumb (1% rule, 50% rule) give you a fast filter; the full model tells you whether that filter was telling the truth.

Real estate is one of the most common paths to FIRE outside of a traditional stock portfolio, but it carries a different risk profile. Unlike index funds, a single rental property is concentrated, illiquid, and operationally demanding. Running the numbers honestly, including vacancy, repairs, capital expenditures, and management, is the difference between a real investment and wishful thinking.

How This Calculator Works

The calculator works in four layers: total income, the two quick rules of thumb, a full expense model, and finally cash-on-cash return on your actual invested dollars. Each layer refines the picture.

1% Rule
Monthly rent divided by purchase price. If the result is at least 1%, the property has a reasonable shot at positive cash flow. Below 1% means expenses likely outpace income -- still worth running the full model, but the bar is higher.
50% Rule
A rough estimate that half of gross rental income will go to operating expenses (not including mortgage). Used to quickly size whether cash flow is even plausible before building a detailed budget.
Variable expenses (vacancy, repairs, capex, management)
These four categories are the ones most commonly underestimated. Vacancy erodes income; repairs and capital expenses (roof, HVAC, appliances) are infrequent but large; property management turns time cost into cash cost. The defaults (5%, 5%, 10%, 10%) are commonly used starting points, not guarantees.
Cash-on-cash return
Annual cash flow divided by total cash invested (down payment + closing costs + repair budget). This is the most apples-to-apples comparison with other investments, because it measures return on the actual capital you deployed.
Cash-on-Cash Return = (Monthly Cash Flow x 12) / Total Cash Invested

Personal Considerations

Rental properties attract a specific kind of motivated reasoning: the optimistic investor mentally increases rent, halves the vacancy estimate, and excludes the repair reserve to make the deal work on paper. The 50% rule exists partly to counteract this -- it forces you to admit that half the income is spoken for before you even look at the mortgage. If the math only works when you assume everything goes right, the math doesn't work.

There's also the identity dimension that overlaps with FIRE broadly. Some people who pursue real estate aren't really drawn to the financial return; they want the psychological security of owning something tangible, something that feels less abstract than a brokerage account balance. That's worth knowing about yourself, because it affects how much underperformance you'll tolerate and whether you'll make clear-eyed decisions when problems arise.

If what you're feeling goes beyond what a calculator can help with, licensed clinicians are available at SanaNetwork.com, a referral network founded by this site's founder, Dr. Yoendry Torres.

Frequently Asked Questions

What's the difference between cash flow and cash-on-cash return?

Cash flow is the monthly dollar amount left after all expenses and the mortgage. Cash-on-cash return annualizes that cash flow and expresses it as a percentage of the total cash you invested (down payment, closing costs, repairs). A property might have modest monthly cash flow but a high cash-on-cash return if you put very little down -- or decent cash flow but a low return if you paid all cash.

Why does the 50% rule exclude the mortgage?

Because the mortgage depends on your financing, not the property's operating performance. The 50% rule is designed to estimate operating expenses only, as a quick stress test of income vs. costs. The mortgage gets added back when you calculate actual cash flow.

Are the default variable expense rates (5/5/10/10) right for my market?

They're reasonable starting points based on commonly cited industry guidelines, but they vary by property type, age, and location. Older properties often need higher repair and capex reserves. Self-managing removes the 10% management fee but adds real time cost. If you're modeling a specific deal, adjust these to match local vacancy rates and your actual management plan.

Why include capital expenditures (capex) as a monthly expense?

Because capital items -- roofs, HVAC systems, water heaters, appliances -- will eventually need replacement, and the cost is large. Setting aside a monthly reserve (modeled here as a percentage of income) means that cost is already accounted for in your return rather than showing up as a surprise that wipes out years of cash flow.

Does this calculator account for appreciation?

No. Appreciation is excluded intentionally because it's speculative -- it varies enormously by market and time period, and projecting it tends to make bad deals look good. Cash flow and cash-on-cash return are the measurable, year-one reality. If the property also appreciates, that's a bonus.