.rental-calculator-wrapper {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
background: #fff;
padding: 20px;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0,0,0,0.1);
color: #333;
}
.rental-calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 768px) {
.rental-calc-grid {
grid-template-columns: 1fr;
}
}
.rental-input-group {
margin-bottom: 15px;
}
.rental-input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 14px;
color: #2c3e50;
}
.rental-input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.rental-input-group input:focus {
border-color: #3498db;
outline: none;
}
.rental-section-title {
grid-column: 1 / -1;
font-size: 18px;
border-bottom: 2px solid #f0f0f0;
padding-bottom: 10px;
margin-top: 10px;
margin-bottom: 15px;
color: #2c3e50;
}
.rental-btn {
grid-column: 1 / -1;
background-color: #27ae60;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background 0.3s;
text-transform: uppercase;
}
.rental-btn:hover {
background-color: #219150;
}
.rental-results {
grid-column: 1 / -1;
background-color: #f8f9fa;
border-radius: 6px;
padding: 20px;
margin-top: 20px;
border-left: 5px solid #27ae60;
}
.rental-result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
font-size: 16px;
}
.rental-result-row.highlight {
font-weight: bold;
font-size: 20px;
color: #27ae60;
border-top: 1px solid #ddd;
padding-top: 10px;
margin-top: 10px;
}
.rental-metric-box {
display: flex;
justify-content: space-between;
margin-top: 20px;
gap: 10px;
}
.metric-card {
background: white;
padding: 15px;
border-radius: 4px;
text-align: center;
flex: 1;
box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}
.metric-card span {
display: block;
font-size: 12px;
color: #7f8c8d;
text-transform: uppercase;
}
.metric-card strong {
display: block;
font-size: 18px;
color: #2c3e50;
margin-top: 5px;
}
function calculateRental() {
// Get inputs
var price = parseFloat(document.getElementById('propPrice').value) || 0;
var down = parseFloat(document.getElementById('propDown').value) || 0;
var rate = parseFloat(document.getElementById('propRate').value) || 0;
var term = parseFloat(document.getElementById('propTerm').value) || 0;
var rent = parseFloat(document.getElementById('propRent').value) || 0;
var tax = parseFloat(document.getElementById('propTax').value) || 0;
var ins = parseFloat(document.getElementById('propIns').value) || 0;
var maintPercent = parseFloat(document.getElementById('propMaint').value) || 0;
var vacancyPercent = parseFloat(document.getElementById('propVacancy').value) || 0;
var capexPercent = parseFloat(document.getElementById('propCapex').value) || 0;
// Calculations
var loanAmount = price – down;
var monthlyRate = (rate / 100) / 12;
var numPayments = term * 12;
// Mortgage Payment (PI)
var mortgage = 0;
if (loanAmount > 0 && rate > 0) {
mortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
} else if (loanAmount > 0 && rate === 0) {
mortgage = loanAmount / numPayments;
}
// Income adjustments
var vacancyCost = rent * (vacancyPercent / 100);
var effectiveIncome = rent – vacancyCost;
// Expenses
var monthlyTax = tax / 12;
var monthlyIns = ins / 12;
var monthlyMaint = rent * (maintPercent / 100);
var monthlyCapex = rent * (capexPercent / 100);
var totalMonthlyOpEx = monthlyTax + monthlyIns + monthlyMaint + monthlyCapex;
// Metrics
var noiMonthly = effectiveIncome – totalMonthlyOpEx;
var cashFlow = noiMonthly – mortgage;
var annualNOI = noiMonthly * 12;
var annualCashFlow = cashFlow * 12;
// ROI Calculations
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
var cocRoi = 0;
var totalInvested = down; // Could add closing costs here if field existed
if (totalInvested > 0) {
cocRoi = (annualCashFlow / totalInvested) * 100;
}
// Formatting currency
var fmt = new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' });
var fmtPct = new Intl.NumberFormat('en-US', { style: 'percent', minimumFractionDigits: 2 });
// Output
document.getElementById('resGross').innerText = fmt.format(rent);
document.getElementById('resVacancy').innerText = "-" + fmt.format(vacancyCost);
document.getElementById('resExpenses').innerText = "-" + fmt.format(totalMonthlyOpEx);
document.getElementById('resMortgage').innerText = "-" + fmt.format(mortgage);
var cfEl = document.getElementById('resCashFlow');
cfEl.innerText = fmt.format(cashFlow);
cfEl.style.color = cashFlow >= 0 ? '#27ae60' : '#e74c3c';
document.getElementById('resNOI').innerText = fmt.format(annualNOI);
document.getElementById('resCOC').innerText = cocRoi.toFixed(2) + "%";
document.getElementById('resCap').innerText = capRate.toFixed(2) + "%";
// Show results
document.getElementById('resultsArea').style.display = 'block';
}
Purchase & Loan Details
Income & Expenses
Monthly Income (Gross):
– Vacancy Loss:
– Monthly Expenses (Tax/Ins/Maint):
– Monthly Mortgage Payment:
Net Monthly Cash Flow:
NOI (Annual)
Cash on Cash ROI
Cap Rate
Understanding Rental Property Cash Flow Analysis
Investing in real estate is one of the most reliable ways to build long-term wealth, but not every property is a good investment. The difference between a profitable asset and a financial liability often comes down to one metric: Cash Flow. Our Rental Property Calculator helps investors analyze potential deals by accounting for income, expenses, and financing costs to determine the true viability of a rental property.
How to Interpret the Metrics
This calculator provides several critical Key Performance Indicators (KPIs) for real estate investors:
- Net Monthly Cash Flow: This is the profit left over after paying all operating expenses and the mortgage. A positive cash flow means the property pays for itself and puts money in your pocket every month. Many investors aim for $100–$300 per door per month.
- Cash on Cash ROI (CoC): This measures the return on the actual cash you invested (down payment + closing costs), rather than the total price of the property. It is calculated as Annual Cash Flow / Total Cash Invested. A CoC ROI of 8-12% is often considered a solid benchmark for rental properties.
- Cap Rate (Capitalization Rate): This metric helps compare the profitability of properties regardless of how they are financed. It represents the rate of return on the property if you paid all cash. It is calculated as Net Operating Income (NOI) / Purchase Price.
- Net Operating Income (NOI): This is the total income generated by the property minus all necessary operating expenses, but before debt service (mortgage payments). NOI is critical for determining the property's intrinsic value.
The 50% Rule and Vacancy Rates
When analyzing a deal quickly, seasoned investors often use the "50% Rule," which suggests that 50% of your rental income will go toward operating expenses (excluding the mortgage). While our calculator allows you to input specific values for taxes, insurance, and maintenance, keeping this rule in mind can help you spot unrealistic assumptions.
Additionally, never assume 100% occupancy. Even in hot markets, tenants move out, and units require turnover time for repairs. A standard vacancy rate to factor into your analysis is 5% to 8%, though this varies by location.
Why Capital Expenditures (CapEx) Matter
Many new investors fail to account for Capital Expenditures (CapEx). Unlike routine maintenance (like fixing a leaky faucet), CapEx refers to major replacements such as a new roof, HVAC system, or water heater. These are expensive and infrequent, but they will happen eventually. Setting aside 5-10% of monthly rent into a reserve fund for CapEx ensures that your cash flow calculations remain accurate over the long term, preventing a sudden expense from wiping out years of profit.