.calculator-container {
font-family: '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(0,0,0,0.05);
}
.calc-header {
text-align: center;
margin-bottom: 30px;
background-color: #2c3e50;
color: #fff;
padding: 20px;
border-radius: 8px;
}
.calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.calc-grid {
grid-template-columns: 1fr;
}
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
color: #333;
font-size: 0.9em;
}
.input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.input-group input:focus {
border-color: #3498db;
outline: none;
}
.calc-btn {
width: 100%;
padding: 15px;
background-color: #27ae60;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
margin-top: 20px;
transition: background-color 0.3s;
}
.calc-btn:hover {
background-color: #219150;
}
.results-section {
margin-top: 30px;
background-color: #f8f9fa;
padding: 20px;
border-radius: 8px;
border-left: 5px solid #27ae60;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding-bottom: 10px;
border-bottom: 1px solid #e9ecef;
}
.result-row:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
}
.result-label {
color: #555;
font-weight: 500;
}
.result-value {
font-weight: bold;
color: #2c3e50;
}
.highlight-result {
font-size: 1.2em;
color: #27ae60;
}
.calc-article {
margin-top: 40px;
line-height: 1.6;
color: #444;
}
.calc-article h2 {
color: #2c3e50;
margin-top: 30px;
font-size: 1.5em;
}
.calc-article h3 {
color: #34495e;
font-size: 1.2em;
margin-top: 20px;
}
.calc-article p {
margin-bottom: 15px;
}
.calc-article ul {
margin-bottom: 20px;
padding-left: 20px;
}
.calc-article li {
margin-bottom: 8px;
}
.error-msg {
color: #e74c3c;
text-align: center;
margin-top: 10px;
display: none;
}
Please enter valid numbers in all fields.
Investment Analysis
Monthly Cash Flow
$0.00
Cash on Cash Return (ROI)
0.00%
Total Cash Needed to Close
$0.00
Monthly Mortgage (P&I)
$0.00
Total Monthly Expenses
$0.00
Net Operating Income (Monthly)
$0.00
Understanding Rental Property Cash Flow
Investing in real estate is a powerful way to build wealth, but simply buying a property doesn't guarantee a profit. The most critical metric for any buy-and-hold investor is Cash Flow. This calculator helps you break down the income and expenses associated with a potential rental property to determine if it is a sound financial investment.
How is Cash Flow Calculated?
Positive cash flow occurs when a property's gross income exceeds all of its expenses. The basic formula used in this calculator is:
Cash Flow = Gross Rental Income – Total Expenses
Where total expenses include:
- Mortgage Principal & Interest: The monthly debt service paid to the bank.
- Taxes & Insurance: Recurring costs mandated by local governments and lenders.
- Operating Expenses: HOA fees, property management, and utilities.
- Reserves: Allocations for maintenance repairs and vacancy periods (when the unit sits empty).
What is Cash on Cash Return (CoC)?
While cash flow tells you how much money you end up with each month, the Cash on Cash Return tells you how hard your money is working. It measures the annual return on the actual cash you invested, rather than the total value of the property.
For example, if you invest $50,000 (down payment + closing costs) and the property generates $5,000 in net positive cash flow per year, your Cash on Cash return is 10%. This metric is essential for comparing real estate performance against other investment vehicles like stocks or bonds.
Why Factor in Maintenance and Vacancy?
A common mistake new investors make is assuming 100% occupancy and zero repairs. In reality, roofs leak, appliances break, and tenants move out. This calculator allows you to set a percentage of monthly rent aside for these inevitable costs. A standard industry rule of thumb is to allocate at least 5-10% for maintenance and 5-8% for vacancy, depending on the property age and location.
Interpreting Your Results
Positive Cash Flow: The property pays for itself and generates income. This is generally the goal for long-term wealth building.
Negative Cash Flow: The property costs you money every month to hold. While appreciation might offset this over time, negative cash flow is risky and generally advised against for beginner investors.
function calculateCashFlow() {
// Get Input Values
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPercent = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var term = parseFloat(document.getElementById('loanTerm').value);
var closingCosts = parseFloat(document.getElementById('closingCosts').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var taxYearly = parseFloat(document.getElementById('propertyTax').value);
var insuranceYearly = parseFloat(document.getElementById('insurance').value);
var hoa = parseFloat(document.getElementById('hoa').value);
var maintPercent = parseFloat(document.getElementById('maintenance').value);
// Validation
if (isNaN(price) || isNaN(downPercent) || isNaN(rate) || isNaN(term) ||
isNaN(rent) || isNaN(taxYearly) || isNaN(insuranceYearly)) {
document.getElementById('errorDisplay').style.display = 'block';
document.getElementById('resultsArea').style.display = 'none';
return;
}
document.getElementById('errorDisplay').style.display = 'none';
// Calculations
// 1. Initial Cash Invested
var downPaymentAmount = price * (downPercent / 100);
var totalCashInvested = downPaymentAmount + closingCosts;
// 2. Loan Calculations
var loanAmount = price – downPaymentAmount;
var monthlyRate = (rate / 100) / 12;
var totalPayments = term * 12;
// Mortgage Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyMortgage = 0;
if (rate > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalPayments)) / (Math.pow(1 + monthlyRate, totalPayments) – 1);
} else {
monthlyMortgage = loanAmount / totalPayments;
}
// 3. Monthly Expenses
var monthlyTax = taxYearly / 12;
var monthlyInsurance = insuranceYearly / 12;
var monthlyMaintAndVacancy = rent * (maintPercent / 100);
var totalMonthlyExpenses = monthlyMortgage + monthlyTax + monthlyInsurance + hoa + monthlyMaintAndVacancy;
// 4. Returns
var monthlyCashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// Cash on Cash Return = (Annual Cash Flow / Total Cash Invested) * 100
var cocReturn = 0;
if (totalCashInvested > 0) {
cocReturn = (annualCashFlow / totalCashInvested) * 100;
}
// Net Operating Income (NOI) = (Revenue – Operating Expenses) (Excluding Mortgage)
// Operating Expenses = Tax + Ins + HOA + Maint/Vacancy
var operatingExpenses = monthlyTax + monthlyInsurance + hoa + monthlyMaintAndVacancy;
var monthlyNOI = rent – operatingExpenses;
// Display Results
// Format numbers to currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
});
document.getElementById('resCashFlow').innerText = formatter.format(monthlyCashFlow);
document.getElementById('resCashFlow').style.color = monthlyCashFlow >= 0 ? '#27ae60' : '#c0392b';
document.getElementById('resCoc').innerText = cocReturn.toFixed(2) + "%";
document.getElementById('resCoc').style.color = cocReturn >= 0 ? '#27ae60' : '#c0392b';
document.getElementById('resCashNeeded').innerText = formatter.format(totalCashInvested);
document.getElementById('resMortgage').innerText = formatter.format(monthlyMortgage);
document.getElementById('resExpenses').innerText = formatter.format(totalMonthlyExpenses);
document.getElementById('resNOI').innerText = formatter.format(monthlyNOI);
document.getElementById('resultsArea').style.display = 'block';
}