.calculator-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
line-height: 1.6;
}
.calc-container {
background: #f8f9fa;
padding: 30px;
border-radius: 8px;
box-shadow: 0 4px 6px rgba(0,0,0,0.1);
margin-bottom: 40px;
border: 1px solid #e9ecef;
}
.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;
font-size: 0.9em;
color: #495057;
}
.input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.input-group input:focus {
border-color: #4CAF50;
outline: none;
box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.2);
}
.section-title {
grid-column: 1 / -1;
font-size: 1.1em;
font-weight: bold;
color: #2c3e50;
margin-top: 10px;
border-bottom: 2px solid #e9ecef;
padding-bottom: 5px;
margin-bottom: 15px;
}
button.calc-btn {
grid-column: 1 / -1;
background: #2196F3;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background 0.2s;
margin-top: 10px;
}
button.calc-btn:hover {
background: #1976D2;
}
#calc-results {
grid-column: 1 / -1;
background: white;
padding: 20px;
border-radius: 4px;
margin-top: 20px;
border-left: 5px solid #2196F3;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding-bottom: 10px;
border-bottom: 1px solid #eee;
}
.result-row:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
}
.result-label {
font-weight: 500;
color: #666;
}
.result-value {
font-weight: bold;
font-size: 1.1em;
}
.final-result {
margin-top: 15px;
padding-top: 15px;
border-top: 2px solid #eee;
font-size: 1.2em;
color: #2c3e50;
}
.positive-flow {
color: #2e7d32;
}
.negative-flow {
color: #c62828;
}
.calc-content {
margin-top: 40px;
}
.calc-content h2 {
color: #2c3e50;
margin-top: 30px;
}
.calc-content h3 {
color: #34495e;
margin-top: 20px;
}
.calc-content p {
margin-bottom: 15px;
}
.calc-content ul {
margin-bottom: 20px;
padding-left: 20px;
}
.calc-content li {
margin-bottom: 8px;
}
function calculateRentalCashFlow() {
// Get inputs
var price = parseFloat(document.getElementById('purchasePrice').value);
var down = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var years = parseFloat(document.getElementById('loanTerm').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var taxYearly = parseFloat(document.getElementById('propertyTax').value);
var insYearly = parseFloat(document.getElementById('insurance').value);
var hoa = parseFloat(document.getElementById('hoa').value);
var vacancyPct = parseFloat(document.getElementById('vacancyRate').value);
var maintPct = parseFloat(document.getElementById('maintenanceRate').value);
// Validation
if (isNaN(price) || isNaN(down) || isNaN(rate) || isNaN(years) || isNaN(rent)) {
alert("Please enter valid numbers for all fields.");
return;
}
// 1. Calculate Mortgage (Principal & Interest)
var loanAmount = price – down;
var monthlyRate = (rate / 100) / 12;
var numPayments = years * 12;
var monthlyPI = 0;
if (rate === 0) {
monthlyPI = loanAmount / numPayments;
} else {
monthlyPI = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
}
// 2. Calculate Monthly Operating Expenses
var monthlyTax = taxYearly / 12;
var monthlyIns = insYearly / 12;
var monthlyVacancy = rent * (vacancyPct / 100);
var monthlyMaint = rent * (maintPct / 100);
var totalOperatingExpenses = monthlyTax + monthlyIns + hoa + monthlyVacancy + monthlyMaint;
// 3. Totals
var totalMonthlyOutflow = monthlyPI + totalOperatingExpenses;
var monthlyCashFlow = rent – totalMonthlyOutflow;
var annualCashFlow = monthlyCashFlow * 12;
// 4. Cash on Cash Return
// Assuming closing costs are roughly 3% of purchase price for a more accurate CoC estimation,
// but for this specific calculator inputs, we will base it strictly on Down Payment to match inputs provided.
var cashInvested = down;
var cocReturn = 0;
if (cashInvested > 0) {
cocReturn = (annualCashFlow / cashInvested) * 100;
}
// Display Results
document.getElementById('result-pi').innerHTML = '$' + monthlyPI.toFixed(2);
document.getElementById('result-expenses').innerHTML = '$' + totalOperatingExpenses.toFixed(2);
document.getElementById('result-total-outflow').innerHTML = '$' + totalMonthlyOutflow.toFixed(2);
var cashFlowEl = document.getElementById('result-cashflow');
cashFlowEl.innerHTML = (monthlyCashFlow = 0) {
cashFlowEl.className = "result-value positive-flow";
} else {
cashFlowEl.className = "result-value negative-flow";
}
var annualEl = document.getElementById('result-annual-cashflow');
annualEl.innerHTML = (annualCashFlow = 0) {
annualEl.className = "result-value positive-flow";
} else {
annualEl.className = "result-value negative-flow";
}
document.getElementById('result-coc').innerHTML = cocReturn.toFixed(2) + '%';
// Show results div
document.getElementById('calc-results').style.display = 'block';
}
Purchase & Loan Details
Income & Expenses
Monthly Principal & Interest:
$0.00
Operating Expenses (Tax, Ins, Maint, etc):
$0.00
Total Monthly Outflow:
$0.00
Net Monthly Cash Flow:
$0.00
Annual Cash Flow:
$0.00
Cash on Cash Return:
0.00%
How to Calculate Rental Property Cash Flow
Calculating cash flow is the most critical step in evaluating a real estate investment. Positive cash flow ensures that the property pays for itself while you build equity. This calculator helps investors determine the viability of a rental property by factoring in mortgage payments, operating expenses, vacancy allowances, and long-term maintenance costs.
Understanding the Inputs
- Purchase Price & Down Payment: The foundation of your loan calculation. A larger down payment reduces monthly mortgage costs, improving cash flow.
- Vacancy Rate: No property is occupied 100% of the time. We recommend setting aside 5-8% of gross rent to account for turnover periods.
- Maintenance / CapEx: Even if the house is new, you must budget for repairs. Setting aside 5-10% of monthly rent creates a safety net for when a water heater breaks or a roof needs patching.
- HOA Fees: Homeowner Association fees can significantly eat into profits, especially in condos or managed communities.
Key Metrics Explained
Net Monthly Cash Flow: This is the amount of profit you pocket every month after all expenses are paid. A general rule of thumb for many investors is to aim for at least $100-$200 per door in positive cash flow.
Cash on Cash Return (CoC): This metric measures the annual return on the actual cash you invested (Down Payment). It is calculated as (Annual Cash Flow / Total Cash Invested) * 100. A CoC return of 8-12% is often considered a solid investment in the real estate market.
Why Cash Flow Matters
While appreciation (the increase in property value over time) is a great wealth builder, cash flow is what keeps your business afloat. Properties with negative cash flow are liabilities that require monthly contributions from your personal income to sustain. Always prioritize positive cash flow to mitigate risk during market downturns.