Rental Property Cash Flow Calculator
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Investment Analysis
Cash on Cash Return
0.00%
Monthly Principal & Interest:
$0.00
Total Monthly Expenses:
$0.00
Net Operating Income (Annual):
$0.00
Understanding Rental Property Cash Flow
Investing in real estate is one of the most reliable ways to build wealth, but not every property is a good deal. The difference between a profitable asset and a money pit lies in the numbers. This Rental Property Cash Flow Calculator helps you analyze potential investment properties to determine if they will generate positive income.
What is Cash Flow?
Cash flow is the profit you take home each month after all operating expenses and mortgage payments have been made. Positive cash flow means the property is putting money into your pocket, while negative cash flow means you are paying monthly to hold the property.
Formula:
Monthly Cash Flow = Monthly Rental Income – (Mortgage + Taxes + Insurance + HOA + Maintenance + Vacancy)
Key Metrics Explained
This calculator provides three critical metrics for real estate investors:
- Cash Flow: The net amount of cash moving in or out of the investment monthly.
- Cash on Cash Return (CoC): A percentage measuring the annual return on the actual cash you invested (Down Payment + Closing Costs). It tells you how hard your money is working.
- Cap Rate (Capitalization Rate): A measure of the property's natural rate of return assuming you bought it with all cash. It helps compare properties regardless of financing.
How to Analyze the Results
| Metric |
Good Target |
Explanation |
| Cash Flow |
$200+ / door |
Ensures a buffer for unexpected repairs and vacancy. |
| Cash on Cash |
8% – 12% |
Compares favorably against the stock market average. |
| Cap Rate |
5% – 10% |
Higher is better for returns, but often comes with higher risk areas. |
Why Use a Cash Flow Calculator?
Many new investors make the mistake of only looking at the mortgage payment versus the rent. They forget to account for "phantom" costs like vacancy, repairs, CapEx (Capital Expenditures), and property management. Using a comprehensive calculator ensures you aren't blindsided by expenses that eat up your profit.
Common Expenses to Watch Out For
When entering your numbers above, be realistic about maintenance. Even if a house is new, things break. A standard rule of thumb is to budget 5-10% of the rent for maintenance and another 5-10% for vacancy (periods where the property sits empty between tenants).
function calculateCashFlow() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPercent = parseFloat(document.getElementById('downPayment').value);
var closingCosts = parseFloat(document.getElementById('closingCosts').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var termYears = parseFloat(document.getElementById('loanTerm').value);
var monthlyRent = parseFloat(document.getElementById('monthlyRent').value);
var annualTax = parseFloat(document.getElementById('propertyTax').value);
var annualIns = parseFloat(document.getElementById('insurance').value);
var monthlyHoa = parseFloat(document.getElementById('hoa').value);
var monthlyMaint = parseFloat(document.getElementById('maintenance').value);
// Validation to prevent NaN errors
if (isNaN(price) || isNaN(downPercent) || isNaN(interestRate) || isNaN(termYears) || isNaN(monthlyRent)) {
alert("Please enter valid numbers for all fields.");
return;
}
// 2. Calculate Mortgage (Principal & Interest)
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = termYears * 12;
var monthlyMortgage = 0;
if (interestRate === 0) {
monthlyMortgage = loanAmount / numberOfPayments;
} else {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
// 3. Calculate Monthly Expenses
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
// Total Operating Expenses (Tax, Ins, HOA, Maint)
var operatingExpenses = monthlyTax + monthlyIns + monthlyHoa + monthlyMaint;
// Total Expenses (Operating + Debt Service)
var totalMonthlyExpenses = operatingExpenses + monthlyMortgage;
// 4. Calculate Cash Flow
var monthlyCashFlow = monthlyRent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// 5. Calculate NOI (Net Operating Income) -> Rent – Operating Expenses (Excludes Mortgage)
var annualNOI = (monthlyRent * 12) – (operatingExpenses * 12);
// 6. Calculate Cap Rate -> (Annual NOI / Purchase Price) * 100
var capRate = (annualNOI / price) * 100;
// 7. Calculate Cash on Cash Return -> (Annual Cash Flow / Total Cash Invested) * 100
var totalCashInvested = downPaymentAmount + closingCosts;
var cashOnCash = (annualCashFlow / totalCashInvested) * 100;
// 8. Update UI
// Format Currency Function
function formatCurrency(num) {
return '$' + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
// Update Result Elements
document.getElementById('resCashFlow').innerText = formatCurrency(monthlyCashFlow);
document.getElementById('resCoC').innerText = cashOnCash.toFixed(2) + "%";
document.getElementById('resCapRate').innerText = capRate.toFixed(2) + "%";
document.getElementById('resMortgage').innerText = formatCurrency(monthlyMortgage);
document.getElementById('resTotalExp').innerText = formatCurrency(totalMonthlyExpenses);
document.getElementById('resNOI').innerText = formatCurrency(annualNOI);
// Color Coding for Cash Flow
var cashFlowElement = document.getElementById('resCashFlow');
if (monthlyCashFlow >= 0) {
cashFlowElement.className = "result-value positive";
} else {
cashFlowElement.className = "result-value negative";
}
}
// Initialize calculation on load so the zeros don't look broken
window.onload = function() {
calculateCashFlow();
};