function calculateRental() {
// Get Input Values
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPaymentPercent = parseFloat(document.getElementById('downPayment').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTerm = parseFloat(document.getElementById('loanTerm').value);
var closingCosts = parseFloat(document.getElementById('closingCosts').value);
var monthlyRent = parseFloat(document.getElementById('monthlyRent').value);
var annualTax = parseFloat(document.getElementById('propertyTax').value);
var annualInsurance = parseFloat(document.getElementById('insurance').value);
var monthlyHOA = parseFloat(document.getElementById('hoa').value);
var maintenancePercent = parseFloat(document.getElementById('maintenance').value);
var vacancyPercent = parseFloat(document.getElementById('vacancy').value);
// Validation
if (isNaN(price) || isNaN(monthlyRent)) {
alert("Please enter valid numbers for Purchase Price and Rental Income.");
return;
}
// Defaults for empty fields if not caught by isNaN (though parseFloat handles empty string as NaN usually)
if (isNaN(downPaymentPercent)) downPaymentPercent = 0;
if (isNaN(closingCosts)) closingCosts = 0;
if (isNaN(monthlyHOA)) monthlyHOA = 0;
if (isNaN(maintenancePercent)) maintenancePercent = 0;
if (isNaN(vacancyPercent)) vacancyPercent = 0;
// 1. Calculate Mortgage (P&I)
var downPaymentAmount = price * (downPaymentPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = loanTerm * 12;
var monthlyMortgage = 0;
if (interestRate > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
} else {
monthlyMortgage = loanAmount / numberOfPayments;
}
// 2. Calculate Operating Expenses
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
var monthlyMaintenance = monthlyRent * (maintenancePercent / 100);
var monthlyVacancy = monthlyRent * (vacancyPercent / 100);
var operatingExpenses = monthlyTax + monthlyInsurance + monthlyHOA + monthlyMaintenance + monthlyVacancy;
var totalMonthlyExpenses = operatingExpenses + monthlyMortgage;
// 3. Calculate Metrics
var monthlyNOI = monthlyRent – operatingExpenses;
var monthlyCashFlow = monthlyNOI – monthlyMortgage;
var annualCashFlow = monthlyCashFlow * 12;
var annualNOI = monthlyNOI * 12;
var totalInitialInvestment = downPaymentAmount + closingCosts;
// Cash on Cash Return = Annual Cash Flow / Total Cash Invested
var cocReturn = 0;
if (totalInitialInvestment > 0) {
cocReturn = (annualCashFlow / totalInitialInvestment) * 100;
}
// Cap Rate = Annual NOI / Purchase Price
var capRate = (annualNOI / price) * 100;
// Display Results
var cashFlowElement = document.getElementById('monthlyCashFlow');
cashFlowElement.innerText = formatCurrency(monthlyCashFlow);
if (monthlyCashFlow < 0) {
cashFlowElement.classList.add('negative');
cashFlowElement.classList.remove('highlight-result');
} else {
cashFlowElement.classList.remove('negative');
cashFlowElement.classList.add('highlight-result');
}
document.getElementById('cocReturn').innerText = cocReturn.toFixed(2) + '%';
document.getElementById('capRate').innerText = capRate.toFixed(2) + '%';
document.getElementById('monthlyNOI').innerText = formatCurrency(monthlyNOI);
document.getElementById('totalExpenses').innerText = formatCurrency(totalMonthlyExpenses);
document.getElementById('mortgagePayment').innerText = formatCurrency(monthlyMortgage);
// Show results div
document.getElementById('results-area').style.display = 'block';
}
function formatCurrency(num) {
return '$' + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
Understanding Rental Property Cash Flow
Investing in real estate is a powerful way to build wealth, but simply buying a property doesn't guarantee profit. The most critical metric for buy-and-hold investors is Cash Flow. This calculator helps you determine if a potential rental property will put money in your pocket every month or become a financial liability.
What is Cash Flow?
Cash flow is the net amount of cash moving into or out of a business or investment. In real estate, it represents the money remaining after all expenses—including the mortgage, taxes, insurance, and maintenance—have been paid from the rental income.
How to Calculate Rental Property Cash Flow
To accurately calculate cash flow, you must account for both fixed and variable expenses. The formula used in our calculator is:
Gross Income: Total monthly rent collected.
Operating Expenses: Property taxes, insurance, HOA fees, maintenance reserves, and vacancy allowances.
Net Operating Income (NOI): Gross Income minus Operating Expenses.
Debt Service: Your monthly mortgage payment (Principal & Interest).
Cash Flow: NOI minus Debt Service.
Key Metrics Explained
Beyond simple cash flow, this tool provides advanced metrics to evaluate your investment performance:
1. Cash on Cash Return (CoC)
This measures the return on the actual cash you invested (down payment + closing costs), rather than the total price of the property. It is calculated as:
CoC ROI = (Annual Cash Flow / Total Cash Invested) × 100
A "good" CoC return varies by market, but many investors aim for 8-12%.
2. Cap Rate (Capitalization Rate)
Cap rate measures a property's natural rate of return assuming it was bought with cash (no mortgage). It allows you to compare properties regardless of financing.
Cap Rate = (Annual NOI / Purchase Price) × 100
Example Calculation
Imagine you purchase a property for $250,000 with 20% down. Your loan is $200,000 at 6.5% interest.
Rental Income: $2,200/month
Mortgage Payment: ~$1,264/month
Taxes & Insurance: ~$350/month
Reserves (Vacancy/Maint): ~$220/month
Total Expenses: ~$1,834/month
Cash Flow: $2,200 – $1,834 = $366/month
Using this calculator ensures you don't overlook hidden costs like vacancy rates (periods where the unit sits empty) and maintenance reserves (saving for future repairs like a new roof or water heater).
{
"@context": "https://schema.org",
"@type": "FAQPage",
"mainEntity": [{
"@type": "Question",
"name": "What is a good cash on cash return for rental property?",
"acceptedAnswer": {
"@type": "Answer",
"text": "While returns vary by market and strategy, most real estate investors target a Cash on Cash (CoC) return between 8% and 12%. However, in highly appreciative markets, investors might accept a lower CoC (4-6%) in exchange for higher equity growth."
}
}, {
"@type": "Question",
"name": "How do I estimate maintenance costs?",
"acceptedAnswer": {
"@type": "Answer",
"text": "A common rule of thumb is to budget 1% of the property value per year for maintenance. Alternatively, many investors set aside 5% to 10% of the monthly rental income to cover repairs and capital expenditures (CapEx)."
}
}, {
"@type": "Question",
"name": "Does this calculator include depreciation?",
"acceptedAnswer": {
"@type": "Answer",
"text": "No, this calculator focuses on cash flow analysis. Depreciation is a non-cash tax deduction that affects your income tax liability but does not impact the monthly cash generated by the property."
}
}]
}