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-wrapper {
background: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
padding: 30px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
margin-bottom: 40px;
}
.calc-title {
text-align: center;
margin-top: 0;
margin-bottom: 25px;
color: #2c3e50;
font-size: 24px;
font-weight: 700;
}
.input-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.input-grid {
grid-template-columns: 1fr;
}
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 14px;
color: #555;
}
.input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box; /* Fix padding issue */
}
.input-group input:focus {
border-color: #3498db;
outline: none;
}
.calc-btn {
width: 100%;
background-color: #27ae60;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
margin-top: 10px;
transition: background 0.3s;
}
.calc-btn:hover {
background-color: #219150;
}
.results-area {
margin-top: 25px;
padding-top: 20px;
border-top: 2px solid #eee;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding: 10px;
background: #fff;
border-radius: 4px;
border-left: 4px solid #3498db;
}
.result-row.highlight {
background-color: #e8f6f3;
border-left-color: #27ae60;
font-weight: bold;
font-size: 1.1em;
}
.result-row.negative {
background-color: #fdedec;
border-left-color: #e74c3c;
}
.result-label {
color: #666;
}
.result-value {
font-weight: 700;
color: #333;
}
.article-section h2 {
color: #2c3e50;
border-bottom: 2px solid #3498db;
padding-bottom: 10px;
margin-top: 30px;
}
.article-section h3 {
color: #2c3e50;
margin-top: 25px;
}
.article-section p, .article-section li {
font-size: 16px;
margin-bottom: 15px;
color: #444;
}
.article-section ul {
padding-left: 20px;
}
.info-box {
background-color: #eaf2f8;
padding: 15px;
border-radius: 5px;
border-left: 4px solid #3498db;
margin: 20px 0;
}
function calculateROI() {
// 1. Get Values
var price = parseFloat(document.getElementById('purchasePrice').value);
var down = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var term = parseFloat(document.getElementById('loanTerm').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var taxes = parseFloat(document.getElementById('annualTaxes').value);
var insurance = parseFloat(document.getElementById('annualInsurance').value);
var maintenance = parseFloat(document.getElementById('monthlyMaintenance').value);
// 2. Validate Inputs
if (isNaN(price) || isNaN(down) || isNaN(rate) || isNaN(term) || isNaN(rent) || isNaN(taxes) || isNaN(insurance) || isNaN(maintenance)) {
alert("Please fill in all fields with valid numbers.");
return;
}
if (down >= price) {
alert("Down payment cannot be equal to or greater than purchase price for this mortgage calculation.");
return;
}
// 3. Logic
var loanAmount = price – down;
var monthlyRate = (rate / 100) / 12;
var numPayments = term * 12;
// Mortgage Calculation Formula
var monthlyMortgage = 0;
if (rate === 0) {
monthlyMortgage = loanAmount / numPayments;
} else {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
}
// Expense Calculations
var monthlyTaxCost = taxes / 12;
var monthlyInsCost = insurance / 12;
var totalMonthlyExpenses = monthlyMortgage + monthlyTaxCost + monthlyInsCost + maintenance;
// ROI Calculations
var monthlyCashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
var cashOnCash = (annualCashFlow / down) * 100;
// Cap Rate Calculation (NOI / Price)
// NOI = Annual Income – Operating Expenses (Excluding Mortgage)
var annualOperatingExpenses = taxes + insurance + (maintenance * 12);
var noi = (rent * 12) – annualOperatingExpenses;
var capRate = (noi / price) * 100;
// 4. Update UI
document.getElementById('displayMortgage').innerHTML = "$" + monthlyMortgage.toFixed(2);
document.getElementById('displayTotalExpenses').innerHTML = "$" + totalMonthlyExpenses.toFixed(2);
var cashFlowEl = document.getElementById('displayCashFlow');
cashFlowEl.innerHTML = "$" + monthlyCashFlow.toFixed(2);
// Styling for positive/negative cash flow
var cashFlowRow = document.getElementById('cashFlowRow');
if (monthlyCashFlow < 0) {
cashFlowRow.classList.add('negative');
cashFlowRow.classList.remove('highlight');
} else {
cashFlowRow.classList.remove('negative');
cashFlowRow.classList.add('highlight');
}
document.getElementById('displayCOC').innerHTML = cashOnCash.toFixed(2) + "%";
document.getElementById('displayCapRate').innerHTML = capRate.toFixed(2) + "%";
document.getElementById('resultContainer').style.display = "block";
}
Mastering Real Estate Investment: Understanding ROI & Cash Flow
Investing in rental properties is one of the most powerful ways to build long-term wealth. However, success isn't guaranteed by simply buying a property and finding a tenant. The difference between a profitable asset and a financial liability lies in the numbers.
Our Rental Property ROI Calculator helps investors analyze deals by breaking down the essential metrics that determine profitability: Cash Flow, Cash on Cash Return, and Cap Rate.
Expert Tip: Always overestimate your expenses. Vacancy rates, unexpected repairs, and capital expenditures (like a new roof) should be factored into your "Monthly Maintenance" buffer to ensure your cash flow remains positive in real-world scenarios.
Key Metrics Explained
1. Monthly Cash Flow
This is the net profit you pocket every month after all bills are paid. It is calculated as:
- Formula: Monthly Rent – (Mortgage + Taxes + Insurance + Maintenance)
Positive cash flow ensures the property pays for itself and provides you with passive income. If this number is negative, you are losing money every month to hold the asset.
2. Cash on Cash Return (CoC ROI)
While cash flow tells you the dollar amount, Cash on Cash Return tells you the efficiency of your money. It measures the annual return on the actual cash you invested (down payment + closing costs).
For example, if you invest $50,000 to buy a house and it generates $5,000 in net profit per year, your CoC return is 10%. This metric allows you to compare real estate against other investments like stocks or bonds.
3. Cap Rate (Capitalization Rate)
Cap Rate measures a property's natural rate of return, independent of debt. It is calculated by dividing the Net Operating Income (NOI) by the property's purchase price. This is crucial for comparing properties quickly, as it ignores the specific mortgage terms you might get.
How to Use This Calculator
To get the most accurate results, ensure you:
- Research Market Rent: Look at comparable listings in the area (comps) to enter a realistic rental income.
- Verify Tax Rates: Property taxes vary significantly by county. Check the local assessor's website.
- Include a Maintenance Buffer: A common rule of thumb is to set aside 10-15% of the rent for repairs and vacancies.
By inputting precise numbers into the fields above, you can make data-driven decisions and avoid emotional buying, ensuring your real estate portfolio remains profitable for years to come.