Rental Property Cash Flow Calculator
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Monthly Mortgage P&I
$0.00
Total Monthly Expenses
$0.00
Net Monthly Cash Flow
$0.00
Annual Cash Flow
$0.00
Cash on Cash Return
0.00%
*Expenses include Mortgage, Tax, Insurance, HOA, and Vacancy Loss.
How to Calculate Rental Property Cash Flow
Investing in real estate is one of the most reliable ways to build wealth, but simply buying a property doesn't guarantee profit. The most critical metric for any buy-and-hold real estate investor is Cash Flow. This calculator helps you determine if a potential rental property will be an asset that puts money in your pocket every month or a liability that drains your savings.
What is Rental Property Cash Flow?
Cash flow is the net amount of money moving into or out of a business, project, or financial product. For a rental property, it is calculated as:
Cash Flow = Gross Rental Income – Total Expenses
If the result is positive, the property is "cash flow positive." If negative, you are losing money every month to hold the property.
Understanding the Inputs
- Purchase Price & Down Payment: These determine your loan amount. A higher down payment reduces your monthly mortgage, thereby increasing cash flow.
- Rental Income: The total amount you charge tenants per month. Be realistic and check local comparables.
- Operating Expenses: These are often underestimated. They include Property Taxes, Insurance, HOA fees, Maintenance, and Capital Expenditures (CapEx).
- Vacancy Rate: Properties are rarely occupied 100% of the time. Deducting a vacancy allowance (typically 5-10%) gives a more realistic view of your income.
Key Metrics Explained
Net Monthly Cash Flow
This is your "take-home" profit after paying the bank, the taxman, insurance companies, and maintenance costs. Most investors aim for at least $100-$300 per door in net positive cash flow.
Cash on Cash (CoC) Return
This metric measures the return on the actual cash you invested (Down Payment + Closing Costs + Rehab Costs). It is calculated as:
(Annual Pre-Tax Cash Flow / Total Cash Invested) × 100
A CoC return of 8-12% is generally considered a solid return in the stock market, and many real estate investors target similar or higher numbers.
Example Scenario
Imagine purchasing a property for $250,000 with $50,000 down. If your mortgage and expenses total $1,800 per month, and you rent it for $2,200, your monthly cash flow is $400. Over a year, that is $4,800. Dividing $4,800 by your initial $50,000 investment yields a 9.6% Cash on Cash Return.
function calculateCashFlow() {
// Get Inputs
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPay = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var years = parseFloat(document.getElementById('loanTerm').value);
var income = parseFloat(document.getElementById('rentalIncome').value);
var taxYear = parseFloat(document.getElementById('propertyTax').value);
var insYear = parseFloat(document.getElementById('insurance').value);
var hoa = parseFloat(document.getElementById('hoaMisc').value);
var vacancy = parseFloat(document.getElementById('vacancyRate').value);
// Validation
if (isNaN(price) || isNaN(downPay) || isNaN(rate) || isNaN(years) || isNaN(income)) {
alert("Please enter valid numbers for all fields.");
return;
}
// Mortgage Calculation
var principal = price – downPay;
var monthlyRate = rate / 100 / 12;
var numPayments = years * 12;
var mortgage = 0;
if (monthlyRate === 0) {
mortgage = principal / numPayments;
} else {
mortgage = principal * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
}
// Expense Calculation
var monthlyTax = taxYear / 12;
var monthlyIns = insYear / 12;
var vacancyLoss = income * (vacancy / 100);
var totalMonthlyExpenses = mortgage + monthlyTax + monthlyIns + hoa + vacancyLoss;
// Cash Flow Calculation
var monthlyCashFlow = income – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// Cash on Cash Return
// Assuming Total Cash Invested = Down Payment for this simplified calculator
// To be more accurate, one would add closing costs, but Down Payment is the primary input here.
var cashInvested = downPay;
var cocReturn = 0;
if (cashInvested > 0) {
cocReturn = (annualCashFlow / cashInvested) * 100;
}
// Display Results
document.getElementById('resMortgage').innerText = "$" + mortgage.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resExpenses').innerText = "$" + totalMonthlyExpenses.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
var cfElement = document.getElementById('resCashFlow');
cfElement.innerText = "$" + monthlyCashFlow.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
// Styling for positive/negative cash flow
if (monthlyCashFlow < 0) {
cfElement.classList.remove('highlight-result');
cfElement.classList.add('highlight-negative');
} else {
cfElement.classList.remove('highlight-negative');
cfElement.classList.add('highlight-result');
}
document.getElementById('resAnnualFlow').innerText = "$" + annualCashFlow.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resCoC').innerText = cocReturn.toFixed(2) + "%";
}