/* Calculator Styles */
.calculator-container {
max-width: 800px;
margin: 2rem auto;
background: #ffffff;
border: 1px solid #e0e0e0;
border-radius: 8px;
box-shadow: 0 4px 12px rgba(0,0,0,0.05);
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
color: #333;
}
.calc-header {
background: #2c3e50;
color: white;
padding: 1.5rem;
border-radius: 8px 8px 0 0;
text-align: center;
}
.calc-header h2 { margin: 0; font-size: 1.5rem; }
.calc-body { padding: 2rem; }
.input-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 1.5rem;
}
@media (max-width: 600px) { .input-grid { grid-template-columns: 1fr; } }
.input-group { margin-bottom: 1rem; }
.input-group label {
display: block;
margin-bottom: 0.5rem;
font-weight: 600;
font-size: 0.9rem;
color: #555;
}
.input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 1rem;
box-sizing: border-box;
}
.input-group input:focus {
border-color: #3498db;
outline: none;
box-shadow: 0 0 5px rgba(52,152,219,0.3);
}
.calc-btn-container {
text-align: center;
margin-top: 1.5rem;
}
.calc-btn {
background: #27ae60;
color: white;
border: none;
padding: 12px 30px;
font-size: 1.1rem;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background 0.2s;
}
.calc-btn:hover { background: #219150; }
.results-section {
margin-top: 2rem;
background: #f8f9fa;
padding: 1.5rem;
border-radius: 6px;
border-left: 5px solid #3498db;
display: none; /* Hidden by default */
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 0.8rem;
font-size: 1rem;
}
.result-row.highlight {
font-weight: bold;
font-size: 1.2rem;
color: #2c3e50;
border-top: 1px solid #ddd;
padding-top: 10px;
margin-top: 10px;
}
.positive-cf { color: #27ae60; }
.negative-cf { color: #c0392b; }
.error-msg {
color: #c0392b;
text-align: center;
margin-top: 10px;
display: none;
}
/* Article Styles */
.article-container {
max-width: 800px;
margin: 3rem auto;
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
line-height: 1.6;
color: #444;
}
.article-container h2 { color: #2c3e50; border-bottom: 2px solid #ecf0f1; padding-bottom: 10px; margin-top: 2rem; }
.article-container h3 { color: #34495e; margin-top: 1.5rem; }
.article-container p { margin-bottom: 1rem; }
.article-container ul { margin-bottom: 1rem; padding-left: 20px; }
.article-container li { margin-bottom: 0.5rem; }
.info-box {
background: #e8f6f3;
border: 1px solid #d1f2eb;
padding: 15px;
border-radius: 4px;
margin: 1.5rem 0;
}
function calculateRentalROI() {
// 1. Get Input Values
var purchasePrice = parseFloat(document.getElementById('purchasePrice').value);
var closingCosts = parseFloat(document.getElementById('closingCosts').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTerm = parseFloat(document.getElementById('loanTerm').value);
var monthlyRent = parseFloat(document.getElementById('monthlyRent').value);
var vacancyRate = parseFloat(document.getElementById('vacancyRate').value);
var annualTaxes = parseFloat(document.getElementById('annualTaxes').value);
var annualInsurance = parseFloat(document.getElementById('annualInsurance').value);
var monthlyMaintenance = parseFloat(document.getElementById('monthlyMaintenance').value);
// 2. Validate Inputs
if (isNaN(purchasePrice) || isNaN(closingCosts) || isNaN(downPayment) ||
isNaN(interestRate) || isNaN(loanTerm) || isNaN(monthlyRent) ||
isNaN(vacancyRate) || isNaN(annualTaxes) || isNaN(annualInsurance) ||
isNaN(monthlyMaintenance)) {
document.getElementById('errorMsg').style.display = 'block';
document.getElementById('results').style.display = 'none';
return;
}
document.getElementById('errorMsg').style.display = 'none';
// 3. Calculation Logic
// Mortgage Calculation
var loanAmount = purchasePrice – downPayment;
var monthlyRate = (interestRate / 100) / 12;
var totalPayments = loanTerm * 12;
var mortgagePayment = 0;
if (monthlyRate > 0) {
mortgagePayment = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalPayments)) / (Math.pow(1 + monthlyRate, totalPayments) – 1);
} else {
mortgagePayment = loanAmount / totalPayments;
}
// Income Calculation (adjusted for vacancy)
var vacancyLoss = monthlyRent * (vacancyRate / 100);
var effectiveIncome = monthlyRent – vacancyLoss;
// Expense Calculation
var monthlyTax = annualTaxes / 12;
var monthlyIns = annualInsurance / 12;
var totalMonthlyExpenses = mortgagePayment + monthlyTax + monthlyIns + monthlyMaintenance;
var operatingExpenses = monthlyTax + monthlyIns + monthlyMaintenance; // Excludes mortgage for Cap Rate
// Cash Flow
var monthlyCashFlow = effectiveIncome – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// ROI Calculation (Cash on Cash)
var totalCashInvested = downPayment + closingCosts;
var cashOnCashROI = 0;
if (totalCashInvested > 0) {
cashOnCashROI = (annualCashFlow / totalCashInvested) * 100;
}
// Cap Rate Calculation (Net Operating Income / Purchase Price)
var netOperatingIncome = (effectiveIncome * 12) – (operatingExpenses * 12);
var capRate = (netOperatingIncome / purchasePrice) * 100;
// 4. Update UI
document.getElementById('resMortgage').innerHTML = '$' + mortgagePayment.toFixed(2);
document.getElementById('resExpenses').innerHTML = '$' + totalMonthlyExpenses.toFixed(2);
document.getElementById('resIncome').innerHTML = '$' + effectiveIncome.toFixed(2);
var cfElement = document.getElementById('resCashFlow');
cfElement.innerHTML = '$' + monthlyCashFlow.toFixed(2);
cfElement.className = monthlyCashFlow >= 0 ? 'positive-cf' : 'negative-cf';
var roiElement = document.getElementById('resROI');
roiElement.innerHTML = cashOnCashROI.toFixed(2) + '%';
roiElement.className = cashOnCashROI >= 0 ? 'positive-cf' : 'negative-cf';
document.getElementById('resCapRate').innerHTML = capRate.toFixed(2) + '%';
document.getElementById('results').style.display = 'block';
}
Understanding Rental Property ROI & Cash Flow
Investing in real estate is one of the most reliable ways to build wealth, but not every property is a good deal. To ensure profitability, investors must look beyond the purchase price and analyze the numbers in detail. This Rental Property Cash Flow Calculator helps you determine the viability of a potential investment by analyzing key metrics like Cash on Cash ROI, Cap Rate, and Net Monthly Cash Flow.
Why Cash Flow is King
Cash Flow is the net amount of money left in your pocket after all expenses—including the mortgage, taxes, insurance, and maintenance—are paid from the rental income. Positive cash flow ensures the property pays for itself and provides you with passive income.
Negative cash flow implies that you must contribute money from other sources to keep the property running, which increases your risk and limits your ability to scale your portfolio.
The 1% Rule: A quick "rule of thumb" used by investors is the 1% rule. It suggests that the monthly rent should be at least 1% of the total purchase price. For example, a $200,000 house should rent for at least $2,000/month. While not a hard rule, it's a good initial filter.
Key Metrics Explained
1. Cash on Cash ROI
Cash on Cash Return on Investment (ROI) measures the annual return you make on the actual cash you invested (Down Payment + Closing Costs), rather than the total loan amount. It gives you a realistic view of how hard your money is working for you.
Formula: (Annual Pre-Tax Cash Flow / Total Cash Invested) x 100
2. Cap Rate (Capitalization Rate)
The Cap Rate measures the natural rate of return of the property assuming it was bought entirely with cash (no mortgage). It is useful for comparing the profitability of different properties regardless of how they are financed.
Formula: (Net Operating Income / Purchase Price) x 100
3. Net Operating Income (NOI)
This is your total revenue minus all necessary operating expenses (vacancy, taxes, insurance, repairs), but excluding mortgage payments. NOI is critical for calculating the Cap Rate.
What Expenses Should You Account For?
Many new investors make the mistake of only calculating the mortgage and taxes. To get an accurate picture, you must include:
- Vacancy Rate: Properties won't be occupied 365 days a year. A standard safe estimate is 5-8% (about 2-3 weeks of vacancy per year).
- Maintenance & CapEx: Even if the house is new, things break. Set aside 5-10% of rent for repairs and future capital expenditures (new roof, HVAC).
- Property Management: If you hire a manager, expect to pay 8-10% of the monthly rent.
Using the Calculator
To use the calculator above, input your purchase details, financing terms, and estimated expenses. Be conservative with your estimates—it is always better to be pleasantly surprised by higher returns than devastated by unexpected costs.