Rental Property Cash Flow Calculator
.rp-calc-container {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
background: #fff;
padding: 20px;
border-radius: 8px;
box-shadow: 0 4px 6px rgba(0,0,0,0.1);
color: #333;
}
.rp-calc-header {
text-align: center;
margin-bottom: 25px;
color: #2c3e50;
}
.rp-input-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.rp-input-grid {
grid-template-columns: 1fr;
}
}
.rp-form-group {
margin-bottom: 15px;
}
.rp-form-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 14px;
color: #555;
}
.rp-form-group input {
width: 100%;
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.rp-form-group input:focus {
border-color: #3498db;
outline: none;
}
.rp-section-title {
grid-column: 1 / -1;
margin-top: 10px;
margin-bottom: 10px;
padding-bottom: 5px;
border-bottom: 2px solid #eee;
font-size: 18px;
color: #2c3e50;
font-weight: bold;
}
.rp-calc-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;
margin-top: 10px;
}
.rp-calc-btn:hover {
background-color: #219150;
}
.rp-results {
margin-top: 30px;
background-color: #f8f9fa;
padding: 20px;
border-radius: 8px;
border-left: 5px solid #3498db;
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 {
font-weight: 500;
}
.rp-result-value {
font-weight: bold;
color: #2c3e50;
}
.rp-highlight {
color: #27ae60;
font-size: 1.2em;
}
.rp-highlight-neg {
color: #e74c3c;
font-size: 1.2em;
}
.rp-article {
max-width: 800px;
margin: 40px auto;
font-family: inherit;
line-height: 1.6;
color: #444;
}
.rp-article h2 {
color: #2c3e50;
margin-top: 30px;
}
.rp-article ul {
margin-bottom: 20px;
}
.rp-article li {
margin-bottom: 10px;
}
Monthly Financial Summary
Gross Monthly Income:
$0.00
Monthly Mortgage Payment (P&I):
$0.00
Total Operating Expenses:
$0.00
Net Monthly Cash Flow:
$0.00
Cash on Cash Return (Annual):
0.00%
Cap Rate:
0.00%
function calculateCashFlow() {
// Retrieve inputs
var price = parseFloat(document.getElementById('purchasePrice').value) || 0;
var downPct = parseFloat(document.getElementById('downPayment').value) || 0;
var rate = parseFloat(document.getElementById('interestRate').value) || 0;
var termYears = parseFloat(document.getElementById('loanTerm').value) || 0;
var closingCosts = parseFloat(document.getElementById('closingCosts').value) || 0;
var rent = parseFloat(document.getElementById('monthlyRent').value) || 0;
var otherInc = parseFloat(document.getElementById('otherIncome').value) || 0;
var annualTax = parseFloat(document.getElementById('annualTax').value) || 0;
var annualIns = parseFloat(document.getElementById('annualInsurance').value) || 0;
var hoa = parseFloat(document.getElementById('hoaFee').value) || 0;
var repairs = parseFloat(document.getElementById('repairs').value) || 0;
var vacancyPct = parseFloat(document.getElementById('vacancyRate').value) || 0;
var mgmtPct = parseFloat(document.getElementById('mgmtFee').value) || 0;
// Calculations
// 1. Loan Calculations
var downAmount = price * (downPct / 100);
var loanAmount = price – downAmount;
var monthlyRate = (rate / 100) / 12;
var numPayments = termYears * 12;
var mortgagePayment = 0;
if (loanAmount > 0 && monthlyRate > 0) {
mortgagePayment = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
} else if (loanAmount > 0 && monthlyRate === 0) {
mortgagePayment = loanAmount / numPayments;
}
// 2. Income
var totalMonthlyIncome = rent + otherInc;
// 3. Variable Expenses
var vacancyCost = totalMonthlyIncome * (vacancyPct / 100);
var mgmtCost = totalMonthlyIncome * (mgmtPct / 100);
// 4. Fixed Monthly Expenses (Pro-rated)
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
var totalOperatingExpenses = monthlyTax + monthlyIns + hoa + repairs + vacancyCost + mgmtCost;
var totalExpenses = totalOperatingExpenses + mortgagePayment;
// 5. Results
var cashFlow = totalMonthlyIncome – totalExpenses;
var annualCashFlow = cashFlow * 12;
var totalInitialInvestment = downAmount + closingCosts;
// Metrics
var cocReturn = 0;
if (totalInitialInvestment > 0) {
cocReturn = (annualCashFlow / totalInitialInvestment) * 100;
}
var noi = (totalMonthlyIncome – totalOperatingExpenses) * 12;
var capRate = 0;
if (price > 0) {
capRate = (noi / price) * 100;
}
// Display Results
document.getElementById('resIncome').innerText = '$' + totalMonthlyIncome.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById('resMortgage').innerText = '$' + mortgagePayment.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById('resExpenses').innerText = '$' + totalOperatingExpenses.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
var cfElement = document.getElementById('resCashFlow');
cfElement.innerText = '$' + cashFlow.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
if (cashFlow >= 0) {
cfElement.className = 'rp-result-value rp-highlight';
} else {
cfElement.className = 'rp-result-value rp-highlight-neg';
}
document.getElementById('resCoC').innerText = cocReturn.toFixed(2) + '%';
document.getElementById('resCapRate').innerText = capRate.toFixed(2) + '%';
// Show result div
document.getElementById('rpResult').style.display = 'block';
}
Understanding Your Rental Property Cash Flow
Investing in real estate is a powerful way to build wealth, but the success of any rental property hinges on the numbers. This Rental Property Cash Flow Calculator helps investors analyze deals quickly to determine if a property will be a liability or a profit-generating asset.
How to Calculate Rental Cash Flow
Cash flow is the net income remaining after all operating expenses and debt service payments have been made. The basic formula used in this calculator is:
Cash Flow = Gross Rental Income – (Operating Expenses + Mortgage Payment)
Key Inputs Explained
- Vacancy Rate: No property is occupied 100% of the time. We recommend estimating 5-8% for vacancy to be safe. This sets aside money for months when the unit is empty.
- Management Fee: If you hire a property manager, they typically charge 8-12% of the monthly rent. Even if you self-manage, it is wise to factor this in to value your own time or prepare for future scaling.
- Repairs & CapEx: Maintenance is inevitable. Setting aside a specific dollar amount (e.g., $150/month) or a percentage ensures you aren't caught off guard by a broken water heater or roof repair.
Evaluating the Results
Once you hit calculate, pay attention to these two critical metrics:
1. Cash on Cash Return (CoC)
This metric measures the annual return on the actual cash you invested (Down Payment + Closing Costs). A common benchmark for a good rental investment is a CoC return between 8% and 12%, though this varies by market strategy.
2. Cap Rate (Capitalization Rate)
Cap Rate calculates the property's natural rate of return without factoring in the mortgage financing. It is calculated as Net Operating Income / Purchase Price. It helps compare the profitability of the property itself against other properties, regardless of how they are financed.
Use this tool to run multiple scenarios—changing your down payment, interest rate, or rental price—to see how sensitive your investment is to market changes.