Rental Property Cash Flow & ROI Calculator
.rp-calculator-widget {
font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 20px auto;
background: #ffffff;
border: 1px solid #e0e0e0;
border-radius: 8px;
box-shadow: 0 4px 12px rgba(0,0,0,0.05);
padding: 30px;
}
.rp-calc-header {
text-align: center;
margin-bottom: 30px;
}
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margin: 0;
font-size: 28px;
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.rp-calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
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@media (max-width: 600px) {
.rp-calc-grid {
grid-template-columns: 1fr;
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.rp-input-group {
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.rp-input-group input, .rp-input-group select {
width: 100%;
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border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
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.rp-input-group input:focus {
border-color: #3498db;
outline: none;
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.rp-section-title {
grid-column: 1 / -1;
font-size: 18px;
color: #34495e;
border-bottom: 2px solid #ecf0f1;
padding-bottom: 10px;
margin-top: 20px;
margin-bottom: 15px;
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text-align: center;
margin-top: 20px;
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button.rp-calc-btn {
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color: white;
border: none;
padding: 15px 40px;
font-size: 18px;
font-weight: bold;
border-radius: 5px;
cursor: pointer;
transition: background-color 0.3s;
}
button.rp-calc-btn:hover {
background-color: #219150;
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.rp-results-container {
grid-column: 1 / -1;
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border: 1px solid #dee2e6;
border-radius: 6px;
padding: 20px;
margin-top: 30px;
display: none; /* Hidden by default */
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display: grid;
grid-template-columns: repeat(3, 1fr);
gap: 15px;
text-align: center;
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@media (max-width: 600px) {
.rp-results-grid {
grid-template-columns: 1fr;
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}
.rp-metric-box {
background: white;
padding: 15px;
border-radius: 4px;
box-shadow: 0 2px 4px rgba(0,0,0,0.05);
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.rp-metric-label {
font-size: 13px;
color: #7f8c8d;
text-transform: uppercase;
letter-spacing: 1px;
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.rp-metric-value {
font-size: 24px;
font-weight: bold;
color: #2c3e50;
margin-top: 5px;
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.rp-metric-value.positive { color: #27ae60; }
.rp-metric-value.negative { color: #c0392b; }
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margin: 40px auto;
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font-family: 'Segoe UI', Roboto, sans-serif;
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margin-top: 30px;
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.rp-content-article h3 {
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.rp-content-article p {
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.rp-content-article ul {
margin-bottom: 15px;
padding-left: 20px;
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.rp-content-article li {
margin-bottom: 8px;
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.rp-error-msg {
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text-align: center;
margin-top: 10px;
display: none;
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}
Understanding Rental Property Investment Metrics
Investing in real estate is one of the most reliable ways to build wealth, but simply buying a property and renting it out doesn't guarantee a profit. To succeed, investors must analyze the numbers rigorously. This Rental Property Calculator is designed to help you determine the viability of a potential investment by calculating three critical metrics: Cash Flow, Cash on Cash Return, and Cap Rate.
1. Monthly Cash Flow
Cash flow is the lifeblood of any rental investment. It is the net amount of money left in your pocket after all expenses and mortgage payments are made.
- Positive Cash Flow: Your income exceeds your expenses. This is the goal for most buy-and-hold investors.
- Negative Cash Flow: Your expenses exceed your income. You are losing money every month to hold the property, often hoping for future appreciation.
Formula: Monthly Rent – (Mortgage + Taxes + Insurance + HOA + Vacancy + Maintenance)
2. Cash on Cash ROI
Cash on Cash Return on Investment (ROI) measures the annual return you make on the actual cash you invested. Unlike a simple yield calculation, this takes into account the leverage (debt) you used to buy the property.
For example, if you invest $50,000 to buy a $200,000 property and it generates $5,000 in annual cash flow, your Cash on Cash ROI is 10%. This metric allows you to compare real estate returns against other investment vehicles like stocks or bonds.
3. Capitalization Rate (Cap Rate)
The Cap Rate indicates the rate of return on a real estate investment property based on the income that the property is expected to generate. It is calculated by dividing the Net Operating Income (NOI) by the property asset value.
Cap Rate is useful for comparing similar properties in the same market, irrespective of financing. A higher cap rate generally implies a higher return but may come with higher risk or a less desirable location.
What are "Vacancy" and "Maintenance" Rates?
Novice investors often forget to account for months when the property sits empty or things break. A safe estimate for most residential properties is to set aside 5% to 10% of the monthly rent for vacancy reserves and another 5% to 10% for maintenance and repairs.
function calculateRentalROI() {
// 1. Get Inputs
var purchasePrice = parseFloat(document.getElementById('purchasePrice').value);
var closingCosts = parseFloat(document.getElementById('closingCosts').value);
var downPaymentPercent = parseFloat(document.getElementById('downPaymentPercent').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTermYears = parseInt(document.getElementById('loanTerm').value);
var monthlyRent = parseFloat(document.getElementById('monthlyRent').value);
var annualPropTax = parseFloat(document.getElementById('annualPropertyTax').value);
var annualInsurance = parseFloat(document.getElementById('annualInsurance').value);
var monthlyHOA = parseFloat(document.getElementById('hoaFees').value);
var vacancyRate = parseFloat(document.getElementById('vacancyRate').value);
var maintenanceRate = parseFloat(document.getElementById('maintenanceRate').value);
var errorDisplay = document.getElementById('errorDisplay');
var resultsArea = document.getElementById('resultsArea');
// 2. Validation
if (isNaN(purchasePrice) || isNaN(monthlyRent) || isNaN(interestRate) || purchasePrice 0) {
if (interestRate === 0) {
monthlyPI = loanAmount / totalMonths;
} else {
monthlyPI = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalMonths)) / (Math.pow(1 + monthlyRate, totalMonths) – 1);
}
}
// Operating Expenses
var monthlyTax = annualPropTax / 12;
var monthlyIns = annualInsurance / 12;
var monthlyVacancyCost = monthlyRent * (vacancyRate / 100);
var monthlyMaintCost = monthlyRent * (maintenanceRate / 100);
var totalMonthlyOperatingExpenses = monthlyTax + monthlyIns + monthlyHOA + monthlyVacancyCost + monthlyMaintCost;
// Net Operating Income (NOI) = Income – Operating Expenses (Excluding Mortgage)
var monthlyNOI = monthlyRent – totalMonthlyOperatingExpenses;
var annualNOI = monthlyNOI * 12;
// Cash Flow = NOI – Mortgage Payment
var monthlyCashFlow = monthlyNOI – monthlyPI;
var annualCashFlow = monthlyCashFlow * 12;
// Returns
var cashOnCashROI = 0;
if (totalCashInvested > 0) {
cashOnCashROI = (annualCashFlow / totalCashInvested) * 100;
}
var capRate = 0;
if (purchasePrice > 0) {
capRate = (annualNOI / purchasePrice) * 100;
}
// 4. Update DOM
// Formatting helper
var currencyFmt = new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' });
var percentFmt = new Intl.NumberFormat('en-US', { minimumFractionDigits: 2, maximumFractionDigits: 2 });
document.getElementById('resCashFlow').innerText = currencyFmt.format(monthlyCashFlow);
document.getElementById('resCocRoi').innerText = percentFmt.format(cashOnCashROI) + "%";
document.getElementById('resCapRate').innerText = percentFmt.format(capRate) + "%";
document.getElementById('resTotalExp').innerText = currencyFmt.format(totalMonthlyOperatingExpenses);
document.getElementById('resMortgage').innerText = currencyFmt.format(monthlyPI);
document.getElementById('resNoi').innerText = currencyFmt.format(annualNOI);
document.getElementById('resTotalInvested').innerText = currencyFmt.format(totalCashInvested);
// Styling for positive/negative flow
var cashFlowEl = document.getElementById('resCashFlow');
if (monthlyCashFlow >= 0) {
cashFlowEl.className = "rp-metric-value positive";
} else {
cashFlowEl.className = "rp-metric-value negative";
}
}