.rp-calculator-container {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
background: #ffffff;
border: 1px solid #e0e0e0;
border-radius: 8px;
box-shadow: 0 4px 12px rgba(0,0,0,0.05);
padding: 0;
overflow: hidden;
}
.rp-calc-header {
background: #2c3e50;
color: #fff;
padding: 20px;
text-align: center;
}
.rp-calc-header h2 {
margin: 0;
font-size: 24px;
}
.rp-calc-body {
padding: 30px;
display: flex;
flex-wrap: wrap;
gap: 30px;
}
.rp-input-section {
flex: 1;
min-width: 300px;
}
.rp-result-section {
flex: 1;
min-width: 300px;
background: #f8f9fa;
padding: 20px;
border-radius: 8px;
border: 1px solid #dee2e6;
}
.rp-form-group {
margin-bottom: 15px;
}
.rp-form-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
color: #333;
font-size: 14px;
}
.rp-input-wrapper {
position: relative;
}
.rp-input-wrapper input {
width: 100%;
padding: 10px 10px 10px 35px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.rp-input-wrapper .currency-symbol {
position: absolute;
left: 12px;
top: 50%;
transform: translateY(-50%);
color: #666;
}
.rp-input-wrapper .percent-symbol {
position: absolute;
right: 12px;
top: 50%;
transform: translateY(-50%);
color: #666;
left: auto;
}
.rp-btn {
width: 100%;
padding: 12px;
background: #27ae60;
color: white;
border: none;
border-radius: 4px;
font-size: 16px;
font-weight: bold;
cursor: pointer;
transition: background 0.3s;
margin-top: 10px;
}
.rp-btn:hover {
background: #219150;
}
.rp-result-row {
display: flex;
justify-content: space-between;
margin-bottom: 15px;
border-bottom: 1px solid #e9ecef;
padding-bottom: 10px;
}
.rp-result-row:last-child {
border-bottom: none;
margin-bottom: 0;
}
.rp-result-label {
color: #555;
font-size: 14px;
}
.rp-result-value {
font-weight: bold;
color: #2c3e50;
font-size: 16px;
}
.rp-highlight {
color: #27ae60;
font-size: 20px;
}
.rp-negative {
color: #c0392b;
}
.rp-article {
max-width: 800px;
margin: 40px auto;
padding: 0 20px;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
}
.rp-article h2 {
color: #2c3e50;
margin-top: 30px;
}
.rp-article h3 {
color: #34495e;
margin-top: 25px;
}
.rp-article p {
margin-bottom: 15px;
}
.rp-article ul {
margin-bottom: 15px;
padding-left: 20px;
}
.rp-article li {
margin-bottom: 8px;
}
Loan Amount:
$0.00
Monthly Mortgage (P&I):
$0.00
Total Monthly Expenses:
$0.00
Monthly Cash Flow:
$0.00
Annual Cash Flow:
$0.00
Cash on Cash ROI:
0.00%
Understanding Rental Property Cash Flow
Investing in real estate is one of the most reliable ways to build wealth, but simply buying a property doesn't guarantee profit. The most critical metric for any buy-and-hold investor is Cash Flow. This calculator helps you determine if a potential rental property is an asset that puts money in your pocket or a liability that takes it out.
How is Cash Flow Calculated?
Cash flow is the net income from a real estate investment after all mortgage payments and operating expenses have been made. The formula used in this calculator is:
Cash Flow = Total Rental Income – (Mortgage Payment + Operating Expenses)
Key Metrics Explained
- Cash on Cash ROI: This measures the annual return on the actual cash you invested (down payment + closing costs), rather than the total price of the property. It is the most accurate way to compare real estate returns against stocks or other investments.
- Operating Expenses: These are the costs to keep the property running. Common mistakes include underestimating vacancy rates, repairs (CapEx), property management fees, taxes, and insurance.
- Positive vs. Negative Gearing: Positive cash flow means the property pays for itself and generates profit. Negative cash flow implies you must contribute money monthly to keep the property, often done in hopes of future appreciation.
Example Scenario
Let's say you purchase a property for $250,000 with a 20% down payment ($50,000). Your loan is $200,000 at 6.5% interest for 30 years.
- Mortgage Payment: Approximately $1,264/month.
- Operating Expenses: $500/month (Taxes, Insurance, HOA).
- Total Outflow: $1,764/month.
- Rent: $2,200/month.
In this scenario, your Monthly Cash Flow is $436 ($5,232/year). Your Cash on Cash ROI would be approximately 10.4%, which is generally considered a strong return in the current market.
function calculateRentalROI() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('rp_price').value);
var downPercent = parseFloat(document.getElementById('rp_down').value);
var interestRate = parseFloat(document.getElementById('rp_rate').value);
var termYears = parseFloat(document.getElementById('rp_term').value);
var rent = parseFloat(document.getElementById('rp_rent').value);
var expenses = parseFloat(document.getElementById('rp_expenses').value);
// Validation to prevent NaN errors
if (isNaN(price) || isNaN(downPercent) || isNaN(interestRate) || isNaN(termYears) || isNaN(rent) || isNaN(expenses)) {
alert("Please enter valid numbers in all fields.");
return;
}
// 2. Perform Calculations
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
// Monthly Mortgage Calculation formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = termYears * 12;
var mortgagePayment = 0;
if (interestRate === 0) {
mortgagePayment = loanAmount / numberOfPayments;
} else {
mortgagePayment = (loanAmount * monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
var totalMonthlyExpenses = mortgagePayment + expenses;
var monthlyCashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// Cash on Cash ROI = Annual Cash Flow / Total Cash Invested (Down Payment)
// Note: For simplicity, this calculator assumes Closing Costs are included or negligible in the "Cash Invested" for the rough estimate,
// strictly using Down Payment as the denominator.
var roi = 0;
if (downPaymentAmount > 0) {
roi = (annualCashFlow / downPaymentAmount) * 100;
}
// 3. Update DOM with Results
// Helper for currency formatting
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
document.getElementById('res_loan').innerHTML = formatter.format(loanAmount);
document.getElementById('res_mortgage').innerHTML = formatter.format(mortgagePayment);
document.getElementById('res_total_exp').innerHTML = formatter.format(totalMonthlyExpenses);
var cashFlowEl = document.getElementById('res_cashflow');
cashFlowEl.innerHTML = formatter.format(monthlyCashFlow);
// Style changes for positive/negative cash flow
if (monthlyCashFlow >= 0) {
cashFlowEl.classList.remove('rp-negative');
cashFlowEl.classList.add('rp-highlight');
} else {
cashFlowEl.classList.remove('rp-highlight');
cashFlowEl.classList.add('rp-negative');
}
document.getElementById('res_annual_cashflow').innerHTML = formatter.format(annualCashFlow);
var roiEl = document.getElementById('res_roi');
roiEl.innerHTML = roi.toFixed(2) + "%";
if (roi >= 0) {
roiEl.classList.remove('rp-negative');
roiEl.classList.add('rp-highlight');
} else {
roiEl.classList.remove('rp-highlight');
roiEl.classList.add('rp-negative');
}
}
// Run calculation once on load to show initial valid state
window.onload = function() {
calculateRentalROI();
};