.rp-calc-container {
max-width: 800px;
margin: 0 auto;
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
padding: 20px;
background: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
}
.rp-calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
.rp-input-group {
margin-bottom: 15px;
}
.rp-input-group label {
display: block;
font-weight: 600;
margin-bottom: 5px;
color: #333;
}
.rp-input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.rp-full-width {
grid-column: 1 / -1;
}
.rp-btn {
background-color: #2c3e50;
color: white;
border: none;
padding: 15px 30px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
border-radius: 4px;
width: 100%;
transition: background 0.3s;
}
.rp-btn:hover {
background-color: #34495e;
}
.rp-results {
margin-top: 30px;
background: white;
padding: 20px;
border-radius: 4px;
box-shadow: 0 2px 5px rgba(0,0,0,0.05);
display: none;
}
.rp-result-row {
display: flex;
justify-content: space-between;
padding: 10px 0;
border-bottom: 1px solid #eee;
}
.rp-result-row:last-child {
border-bottom: none;
}
.rp-result-label {
color: #666;
}
.rp-result-value {
font-weight: bold;
font-size: 18px;
color: #2c3e50;
}
.rp-highlight {
color: #27ae60;
font-size: 22px;
}
.rp-highlight-neg {
color: #c0392b;
font-size: 22px;
}
/* Article Styles */
.rp-article {
max-width: 800px;
margin: 40px auto;
font-family: 'Georgia', serif;
line-height: 1.6;
color: #333;
}
.rp-article h2 {
font-family: 'Segoe UI', sans-serif;
color: #2c3e50;
margin-top: 30px;
}
.rp-article ul {
margin-bottom: 20px;
}
@media (max-width: 600px) {
.rp-calc-grid {
grid-template-columns: 1fr;
}
}
Is Your Rental Property a Good Investment?
Success in real estate investing isn't about guessing; it's about the math. Whether you are analyzing a single-family home, a duplex, or a condo, understanding your numbers is the only way to ensure you are buying an asset rather than a liability. This Rental Property Cash Flow Calculator helps you break down the most critical metrics investors use to evaluate deals.
Key Metrics Explained
1. Monthly Cash Flow
This is the profit you take home every month after all bills are paid. It is calculated by subtracting your total monthly expenses (mortgage, taxes, insurance, repairs, vacancy) from your gross rental income. Positive cash flow is essential for long-term sustainability.
Formula: Rent – (Mortgage + Taxes + Insurance + Operating Expenses)
2. Cash on Cash Return (CoC ROI)
This percentage tells you how hard your actual invested cash is working for you. Unlike a standard ROI calculation that might look at the total asset value, CoC only looks at the money you paid out of pocket (Down Payment + Closing Costs). A CoC return of 8-12% is generally considered a solid target for rental properties.
Example: If you invest $50,000 cash to buy a property and it generates $5,000 in annual profit, your CoC return is 10%.
3. Net Operating Income (NOI)
NOI is the profitability of the property excluding financing costs. It helps you compare the profitability of two buildings regardless of how they were purchased (cash vs. loan).
4. Cap Rate (Capitalization Rate)
Cap Rate measures the natural rate of return on the property. It is calculated by dividing the NOI by the purchase price. In high-demand areas, Cap Rates are usually lower (3-5%), while in riskier or lower-cost areas, they may be higher (7-10%).
How to Use This Calculator
- Purchase Price: The agreed-upon price of the home.
- Down Payment: The percentage of the price you are paying upfront (usually 20-25% for investment loans).
- Operating Expenses: Be realistic. Include estimates for vacancy (5-8%), maintenance (5-10%), and property management (8-10%) if you aren't self-managing.
Use these results to set your maximum offer price. If the Cash Flow is negative, you may need to offer less, increase the rent, or find a different deal.
function calculateRentalROI() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('rp_price').value);
var downPercent = parseFloat(document.getElementById('rp_down').value);
var rate = parseFloat(document.getElementById('rp_rate').value);
var term = parseFloat(document.getElementById('rp_term').value);
var rent = parseFloat(document.getElementById('rp_rent').value);
var annualTax = parseFloat(document.getElementById('rp_tax').value);
var annualIns = parseFloat(document.getElementById('rp_ins').value);
var monthlyOpex = parseFloat(document.getElementById('rp_opex').value);
// 2. Validate Inputs
if (isNaN(price) || isNaN(downPercent) || isNaN(rate) || isNaN(term) || isNaN(rent)) {
alert("Please enter valid numbers in all fields.");
return;
}
// 3. Perform Calculations
// Mortgage Calculation
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = (rate / 100) / 12;
var totalMonths = term * 12;
// Standard Amortization Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyMortgage = 0;
if (rate > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalMonths)) / (Math.pow(1 + monthlyRate, totalMonths) – 1);
} else {
monthlyMortgage = loanAmount / totalMonths;
}
// Monthly Prorated Expenses
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
// Total Monthly Outflow
var totalMonthlyExpenses = monthlyMortgage + monthlyTax + monthlyIns + monthlyOpex;
// Cash Flow
var monthlyCashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// NOI (Net Operating Income) -> Rent – Operating Expenses (Excluding Mortgage P&I)
// Operating Expenses for NOI = Taxes + Insurance + Opex (Maintenance/Vacancy/etc)
var totalOperatingExpensesNOI = monthlyTax + monthlyIns + monthlyOpex;
var monthlyNOI = rent – totalOperatingExpensesNOI;
var annualNOI = monthlyNOI * 12;
// Cash on Cash Return
// Denominator is usually Down Payment + Closing Costs + Rehab.
// For this simple calculator, we use Down Payment Amount.
var cocReturn = 0;
if (downPaymentAmount > 0) {
cocReturn = (annualCashFlow / downPaymentAmount) * 100;
}
// Cap Rate
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
// 4. Update UI
document.getElementById('rp_out_mortgage').innerText = formatCurrency(monthlyMortgage);
document.getElementById('rp_out_expenses').innerText = formatCurrency(totalMonthlyExpenses);
document.getElementById('rp_out_noi').innerText = formatCurrency(monthlyNOI);
var cfElement = document.getElementById('rp_out_cashflow');
cfElement.innerText = formatCurrency(monthlyCashFlow);
// Color coding for cash flow
if (monthlyCashFlow >= 0) {
cfElement.className = "rp-result-value rp-highlight";
} else {
cfElement.className = "rp-result-value rp-highlight-neg";
}
document.getElementById('rp_out_coc').innerText = cocReturn.toFixed(2) + "%";
document.getElementById('rp_out_cap').innerText = capRate.toFixed(2) + "%";
// Show Results
document.getElementById('rp_results').style.display = 'block';
}
function formatCurrency(num) {
return "$" + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}