Please enter valid positive numbers for all fields.
Investment Analysis
Monthly Cash Flow
Cash-on-Cash Return (ROI)
Cap Rate
Net Operating Income (NOI) / Mo
Total Monthly Expenses
Monthly Mortgage Payment
function calculateRental() {
// Clear error
var errorDiv = document.getElementById('errorMsg');
errorDiv.style.display = 'none';
// Get Inputs
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var term = parseFloat(document.getElementById('loanTerm').value);
var closingCosts = parseFloat(document.getElementById('closingCosts').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var vacancy = parseFloat(document.getElementById('vacancyRate').value);
var tax = parseFloat(document.getElementById('propertyTax').value);
var insurance = parseFloat(document.getElementById('insurance').value);
var hoa = parseFloat(document.getElementById('hoaFees').value);
var maintenancePct = parseFloat(document.getElementById('maintenance').value);
// Validation
if (isNaN(price) || isNaN(downPayment) || isNaN(rent) || isNaN(tax) || isNaN(insurance)) {
errorDiv.style.display = 'block';
errorDiv.innerText = "Please fill in all required fields with valid numbers.";
return;
}
if (downPayment > price) {
errorDiv.style.display = 'block';
errorDiv.innerText = "Down payment cannot exceed purchase price.";
return;
}
// Mortgage Calculation
var loanAmount = price – downPayment;
var monthlyRate = (rate / 100) / 12;
var totalMonths = term * 12;
var monthlyMortgage = 0;
if (loanAmount > 0) {
if (rate === 0) {
monthlyMortgage = loanAmount / totalMonths;
} else {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalMonths)) / (Math.pow(1 + monthlyRate, totalMonths) – 1);
}
}
// Income Calculations
var grossMonthlyIncome = rent;
var vacancyLoss = grossMonthlyIncome * (vacancy / 100);
var effectiveIncome = grossMonthlyIncome – vacancyLoss;
// Expense Calculations (Monthly)
var monthlyTax = tax / 12;
var monthlyInsurance = insurance / 12;
var maintenanceCost = grossMonthlyIncome * (maintenancePct / 100);
var totalOperatingExpenses = monthlyTax + monthlyInsurance + hoa + maintenanceCost;
// NOI
var monthlyNOI = effectiveIncome – totalOperatingExpenses;
var annualNOI = monthlyNOI * 12;
// Cash Flow
var monthlyCashFlow = monthlyNOI – monthlyMortgage;
var annualCashFlow = monthlyCashFlow * 12;
// ROI Metrics
var totalCashInvested = downPayment + closingCosts;
var cocReturn = 0;
if (totalCashInvested > 0) {
cocReturn = (annualCashFlow / totalCashInvested) * 100;
}
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
// Display Results
document.getElementById('resCashFlow').innerText = "$" + monthlyCashFlow.toFixed(2);
document.getElementById('resCoc').innerText = cocReturn.toFixed(2) + "%";
document.getElementById('resCapRate').innerText = capRate.toFixed(2) + "%";
document.getElementById('resNOI').innerText = "$" + monthlyNOI.toFixed(2);
document.getElementById('resExpenses').innerText = "$" + totalOperatingExpenses.toFixed(2);
document.getElementById('resMortgage').innerText = "$" + monthlyMortgage.toFixed(2);
// Show result box
document.getElementById('results').style.display = 'block';
}
Understanding Rental Property ROI
Investing in real estate is a powerful way to build wealth, but simply buying a property doesn't guarantee a profit. To succeed, investors must analyze the numbers rigorously. This Rental Property Cash Flow Calculator helps you evaluate the profitability of a potential investment by breaking down income, expenses, and key return metrics.
Key Metrics Explained
1. Cash Flow
Cash flow is the profit you take home each month after all operating expenses and mortgage payments are made. Positive cash flow is essential for a sustainable investment. It provides a safety margin for unexpected repairs and generates passive income.
2. Cash-on-Cash Return (CoC ROI)
This is arguably the most important metric for investors using leverage (a mortgage). It measures the annual return on the actual cash you invested (down payment + closing costs), rather than the total property price. A healthy CoC return often ranges from 8% to 12% or higher, depending on the market and your strategy.
Formula: (Annual Cash Flow / Total Cash Invested) × 100
3. Cap Rate (Capitalization Rate)
The Cap Rate measures the property's natural rate of return assuming you bought it with all cash (no loan). It helps you compare the profitability of different properties regardless of how they are financed. A higher cap rate generally implies higher risk or higher return potential, while a lower cap rate often indicates a safer, more stable asset in a prime location.
Common Expenses to Watch
Vacancy Rate: Properties don't stay rented 365 days a year. Always budget 5-8% of rent for vacancy to account for turnover periods.
Maintenance: Even new homes need repairs. Setting aside 10-15% of the monthly rent ensures you have funds for leaky faucets, HVAC issues, or painting.
HOA Fees: If buying a condo or in a managed community, these monthly fees can significantly eat into your cash flow and are non-negotiable.
How to Use This Calculator
Start by entering the Purchase Price and your financing details. Be accurate with your Interest Rate as this heavily impacts your mortgage payment. Estimate your Monthly Rent by looking at comparable properties (comps) in the area.
Finally, do not underestimate expenses. It is better to be conservative (estimating higher expenses and lower rent) to ensure your investment remains profitable even in a downturn.