Calculate your monthly cash flow and ROI instantly.
Monthly Cash Flow
$0.00
Cash on Cash ROI
$0.00%
Monthly Mortgage (P&I)
$0.00
Total Monthly Expenses
$0.00
Understanding Rental Property Cash Flow
Investing in real estate is one of the most reliable ways to build wealth, but the difference between a good investment and a money pit often comes down to one metric: Cash Flow. This calculator helps you analyze the profitability of a potential rental property before you make an offer.
What is Cash Flow?
Cash flow is the net amount of cash moving in and out of an investment. In real estate, positive cash flow means your monthly rental income exceeds all your expenses (mortgage, taxes, insurance, repairs).
Key Metrics Calculated
Our tool focuses on four critical financial indicators for real estate investors:
Monthly Cash Flow: This is your "take-home" profit every month after all bills are paid. A positive number means the property pays you to own it.
Cash on Cash Return (ROI): This measures the annual return on the actual cash you invested (down payment + closing costs). It allows you to compare real estate returns against stocks or bonds. A result of 8-12% is generally considered strong.
Total Monthly Expenses: Many new investors forget to account for things like vacancy reserves and maintenance. This figure sums up your mortgage plus all operating costs.
Cap Rate (Capitalization Rate): While not explicitly shown above, knowing your expenses allows you to derive the Net Operating Income (NOI), essential for valuing commercial properties.
How to Interpret Your Results
If your calculation shows a negative cash flow, the property will cost you money every month to maintain. This might be acceptable in high-appreciation markets, but it increases your risk. Ideally, you want a property that generates positive cash flow from day one to provide a buffer against vacancies or major repairs.
Use the inputs to test different scenarios: What happens if you negotiate a lower price? What if interest rates drop? Or if you increase the rent? Adjusting these variables will show you the sensitivity of your investment.
function calculateRental() {
// 1. Get Inputs
var price = parseFloat(document.getElementById('propPrice').value) || 0;
var rent = parseFloat(document.getElementById('monthlyRent').value) || 0;
var downPercent = parseFloat(document.getElementById('downPayment').value) || 0;
var rate = parseFloat(document.getElementById('interestRate').value) || 0;
var years = parseFloat(document.getElementById('loanTerm').value) || 0;
var taxYear = parseFloat(document.getElementById('annualTax').value) || 0;
var insYear = parseFloat(document.getElementById('annualInsurance').value) || 0;
var maintPercent = parseFloat(document.getElementById('maintenanceRate').value) || 0;
// 2. Logic Implementation
// Loan Calculation
var downAmount = price * (downPercent / 100);
var loanAmount = price – downAmount;
// Monthly Mortgage Payment (M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1])
var monthlyRate = (rate / 100) / 12;
var numPayments = years * 12;
var mortgage = 0;
if (rate > 0) {
mortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
} else {
mortgage = loanAmount / numPayments;
}
// Monthly Expenses Breakdown
var taxMonth = taxYear / 12;
var insMonth = insYear / 12;
var maintMonth = rent * (maintPercent / 100);
var totalExpenses = mortgage + taxMonth + insMonth + maintMonth;
// Cash Flow Calculation
var cashFlow = rent – totalExpenses;
// Cash on Cash Return Calculation
// Assuming Closing Costs are roughly 3% of purchase price (standard estimate)
var closingCosts = price * 0.03;
var totalCashInvested = downAmount + closingCosts;
var annualCashFlow = cashFlow * 12;
var cashOnCash = 0;
if (totalCashInvested > 0) {
cashOnCash = (annualCashFlow / totalCashInvested) * 100;
}
// 3. Update UI
document.getElementById('resultsSection').style.display = 'block';
// Format helper
function fmtMoney(num) {
return '$' + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
document.getElementById('resCashFlow').innerHTML = fmtMoney(cashFlow);
document.getElementById('resCoc').innerHTML = cashOnCash.toFixed(2) + '%';
document.getElementById('resMortgage').innerHTML = fmtMoney(mortgage);
document.getElementById('resExpenses').innerHTML = fmtMoney(totalExpenses);
// Visual feedback for negative cash flow
var cfCard = document.getElementById('cfCard');
if (cashFlow < 0) {
cfCard.classList.add('negative');
} else {
cfCard.classList.remove('negative');
}
}