function calculateROI() {
// Get Inputs
var price = parseFloat(document.getElementById('purchasePrice').value) || 0;
var downPercent = parseFloat(document.getElementById('downPaymentPercent').value) || 0;
var interestRate = parseFloat(document.getElementById('interestRate').value) || 0;
var loanTerm = parseFloat(document.getElementById('loanTerm').value) || 0;
var closingCosts = parseFloat(document.getElementById('closingCosts').value) || 0;
var monthlyRent = parseFloat(document.getElementById('monthlyRent').value) || 0;
var annualTax = parseFloat(document.getElementById('annualPropertyTax').value) || 0;
var annualIns = parseFloat(document.getElementById('annualInsurance').value) || 0;
var monthlyHOA = parseFloat(document.getElementById('monthlyHOA').value) || 0;
var monthlyMaint = parseFloat(document.getElementById('monthlyMaintenance').value) || 0;
// Calculations
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var totalCashInvested = downPaymentAmount + closingCosts;
// Mortgage Calculation
var monthlyRate = (interestRate / 100) / 12;
var totalPayments = loanTerm * 12;
var monthlyMortgage = 0;
if (interestRate > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalPayments)) / (Math.pow(1 + monthlyRate, totalPayments) – 1);
} else {
monthlyMortgage = loanAmount / totalPayments;
}
// Expense Calculations
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
var totalMonthlyFixedExpenses = monthlyTax + monthlyIns + monthlyHOA + monthlyMaint;
var totalMonthlyExpenses = totalMonthlyFixedExpenses + monthlyMortgage;
// Return Calculations
var monthlyCashFlow = monthlyRent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// NOI = Income – Operating Expenses (Excluding Mortgage)
var annualNOI = (monthlyRent * 12) – (totalMonthlyFixedExpenses * 12);
var cocReturn = 0;
if (totalCashInvested > 0) {
cocReturn = (annualCashFlow / totalCashInvested) * 100;
}
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
// Formatting currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2,
maximumFractionDigits: 2,
});
// Display Results
document.getElementById('results').style.display = 'block';
document.getElementById('resMortgage').innerText = formatter.format(monthlyMortgage);
document.getElementById('resTotalExpenses').innerText = formatter.format(totalMonthlyExpenses);
var cashFlowEl = document.getElementById('resCashFlow');
cashFlowEl.innerText = formatter.format(monthlyCashFlow);
cashFlowEl.style.color = monthlyCashFlow >= 0 ? '#27ae60' : '#c0392b';
document.getElementById('resNOI').innerText = formatter.format(annualNOI);
document.getElementById('resCashInvested').innerText = formatter.format(totalCashInvested);
var cocEl = document.getElementById('resCoC');
cocEl.innerText = cocReturn.toFixed(2) + '%';
cocEl.style.color = cocReturn >= 0 ? '#27ae60' : '#c0392b';
document.getElementById('resCapRate').innerText = capRate.toFixed(2) + '%';
}
Understanding Your Rental Property ROI
Investing in real estate is one of the most reliable ways to build wealth, but knowing your numbers is critical to success. This Rental Property Cash on Cash Return Calculator is designed to help investors evaluate the profitability of a potential rental purchase by analyzing the most important metrics: Cash Flow, Cash on Cash Return, and Cap Rate.
What is Cash on Cash Return?
Cash on Cash (CoC) Return is a metric that calculates the annual return you made on the actual cash you invested. Unlike standard ROI, which might look at the total value of the asset, CoC focuses strictly on the liquidity you put into the deal (Down Payment + Closing Costs). It answers the question: "For every dollar I put in, how much cash am I getting back this year?"
Formula:(Annual Pre-Tax Cash Flow / Total Cash Invested) x 100
Key Metrics Explained
Monthly Cash Flow: This is your profit after all expenses, including the mortgage, are paid. A positive cash flow ensures the property pays for itself and provides income.
NOI (Net Operating Income): This is the annual income generated by the property minus all operating expenses, but excluding the mortgage payments. It measures the property's raw profitability.
Cap Rate: Short for Capitalization Rate, this divides the NOI by the property's purchase price. It allows you to compare the profitability of properties regardless of how they are financed.
How to Improve Your Returns
If your calculation shows a negative cash flow or a low return, consider the following adjustments:
Negotiate the Purchase Price: A lower price reduces your loan amount and monthly mortgage payments.
Increase Rent: Research local market rates. Small increases in monthly rent can significantly boost annual NOI.
Reduce Operating Costs: Shop for cheaper insurance, appeal property taxes, or manage the property yourself to save on management fees.
Larger Down Payment: While this increases your initial cash investment (lowering CoC initially), it reduces monthly debt service, potentially turning a negative cash flow positive.
Example Scenario
Imagine purchasing a property for $250,000 with a 20% down payment ($50,000). If your total monthly expenses including the mortgage are $1,500 and you rent the unit for $2,000, your monthly cash flow is $500. This results in $6,000 annual cash flow. Divided by your initial investment (plus closing costs), you might see a Cash on Cash return of around 10-12%, which is generally considered a solid investment in many markets.