body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
max-width: 800px;
margin: 0 auto;
padding: 20px;
}
.calculator-container {
background: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 30px;
margin-bottom: 40px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.calc-title {
text-align: center;
margin-bottom: 25px;
color: #2c3e50;
}
.input-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.input-grid {
grid-template-columns: 1fr;
}
}
.form-group {
margin-bottom: 15px;
}
.form-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 0.9em;
}
.form-group input {
width: 100%;
padding: 10px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.form-group input:focus {
border-color: #4CAF50;
outline: none;
}
.btn-calc {
width: 100%;
padding: 15px;
background-color: #2c3e50;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
margin-top: 10px;
transition: background-color 0.2s;
}
.btn-calc:hover {
background-color: #1a252f;
}
.results-section {
margin-top: 30px;
padding-top: 20px;
border-top: 2px solid #e9ecef;
display: none;
}
.result-card {
background: white;
padding: 15px;
border-radius: 6px;
margin-bottom: 10px;
border-left: 5px solid #2c3e50;
display: flex;
justify-content: space-between;
align-items: center;
}
.result-card.highlight {
border-left-color: #4CAF50;
background-color: #f0fff4;
}
.result-label {
font-weight: 600;
color: #555;
}
.result-value {
font-weight: bold;
font-size: 1.2em;
color: #2c3e50;
}
.content-article h2 {
color: #2c3e50;
margin-top: 30px;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
}
.content-article p {
margin-bottom: 15px;
}
.content-article ul {
margin-bottom: 20px;
padding-left: 20px;
}
.content-article li {
margin-bottom: 8px;
}
.error-msg {
color: #e74c3c;
text-align: center;
margin-top: 10px;
font-weight: bold;
}
function calculateROI() {
// Clear previous errors
document.getElementById('errorMsg').innerHTML = "";
// Get Inputs
var purchasePrice = parseFloat(document.getElementById('purchasePrice').value);
var downPaymentPercent = parseFloat(document.getElementById('downPaymentPercent').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTerm = parseFloat(document.getElementById('loanTerm').value);
var closingCosts = parseFloat(document.getElementById('closingCosts').value);
var rentalIncome = parseFloat(document.getElementById('rentalIncome').value);
var monthlyExpenses = parseFloat(document.getElementById('monthlyExpenses').value);
// Validation
if (isNaN(purchasePrice) || isNaN(downPaymentPercent) || isNaN(interestRate) ||
isNaN(loanTerm) || isNaN(closingCosts) || isNaN(rentalIncome) || isNaN(monthlyExpenses)) {
document.getElementById('errorMsg').innerHTML = "Please fill in all fields with valid numbers.";
return;
}
// Calculations
var downPaymentAmount = purchasePrice * (downPaymentPercent / 100);
var loanAmount = purchasePrice – downPaymentAmount;
// Mortgage Calculation (Principal & Interest)
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = loanTerm * 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);
}
// Cash Flow Logic
var totalMonthlyCost = monthlyMortgage + monthlyExpenses;
var monthlyCashFlow = rentalIncome – totalMonthlyCost;
var annualCashFlow = monthlyCashFlow * 12;
// Investment Metrics
var totalCashInvested = downPaymentAmount + closingCosts;
// Cash on Cash Return = (Annual Cash Flow / Total Cash Invested) * 100
var cashOnCashReturn = (annualCashFlow / totalCashInvested) * 100;
// Net Operating Income (NOI) = (Rental Income – Operating Expenses) * 12
// Note: Mortgage is not an operating expense for NOI/Cap Rate
var noi = (rentalIncome – monthlyExpenses) * 12;
// Cap Rate = (NOI / Purchase Price) * 100
var capRate = (noi / purchasePrice) * 100;
// Display Results
document.getElementById('resMortgage').innerHTML = "$" + monthlyMortgage.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resTotalExp').innerHTML = "$" + totalMonthlyCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
var cfElement = document.getElementById('resCashFlow');
cfElement.innerHTML = "$" + monthlyCashFlow.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
cfElement.style.color = monthlyCashFlow >= 0 ? "#27ae60" : "#c0392b";
document.getElementById('resCoC').innerHTML = cashOnCashReturn.toFixed(2) + "%";
document.getElementById('resCapRate').innerHTML = capRate.toFixed(2) + "%";
document.getElementById('results').style.display = "block";
}
Understanding Rental Property Investment Metrics
Investing in real estate requires more than just buying a property and collecting rent. To ensure a profitable investment, seasoned investors rely on specific financial metrics to evaluate deals. Our Rental Property ROI Calculator helps you determine the viability of an investment property using three critical indicators: Cash Flow, Cash on Cash Return, and Cap Rate.
1. Monthly Cash Flow
Cash Flow is the net amount of money moving in or out of the investment each month. It is calculated by subtracting your Total Monthly Outflow (Mortgage Principal & Interest + Operating Expenses) from your Monthly Rental Income.
- Positive Cash Flow: The property generates income after all bills are paid. This is the goal for most buy-and-hold investors.
- Negative Cash Flow: The property costs you money to hold every month. This is risky unless you are banking purely on appreciation.
2. Cash on Cash Return (CoC ROI)
While cash flow tells you the dollar amount you make, Cash on Cash Return tells you how hard your money is working. It measures the annual pre-tax cash flow relative to the total amount of cash you invested upfront (Down Payment + Closing Costs + Rehab Costs).
Formula: (Annual Cash Flow / Total Cash Invested) × 100
For example, if you invest $50,000 cash to buy a property that generates $5,000 in positive cash flow per year, your Cash on Cash return is 10%. This allows you to compare real estate returns against other investments like stocks or bonds.
3. Capitalization Rate (Cap Rate)
The Cap Rate measures the property's natural rate of return based on the Net Operating Income (NOI), excluding the influence of mortgage financing. It is calculated by dividing the NOI by the property's purchase price.
Cap Rate is essential for comparing the profitability of similar properties regardless of how they were paid for (cash vs. loan). A higher Cap Rate generally indicates a better return, though it may also come with higher risk or a less desirable location.
How to Use This Calculator
To get the most accurate results, ensure you estimate your Operating Expenses carefully. This field should include:
- Property Taxes (monthly portion)
- Landlord Insurance
- HOA Fees (if applicable)
- Maintenance Reserves (typically 5-10% of rent)
- Vacancy Reserves (typically 5-8% of rent)
- Property Management Fees (if hiring a manager)
By accurately inputting these figures, you can avoid "false positives" and invest in properties that truly meet your financial goals.