Analyze the profitability of your real estate investment instantly.
Purchase Information
30 Years
15 Years
10 Years
Income Information
Recurring Expenses
Monthly Analysis
NOI
$0
Cash on Cash
0%
Cap Rate
0%
Gross Monthly Income:$0.00
Vacancy Loss:-$0.00
Operating Expenses (Tax, Ins, Maint, Mgmt):-$0.00
Monthly Mortgage P&I:-$0.00
Net Monthly Cash Flow:$0.00
function calculateCashFlow() {
// 1. Get Inputs
var price = parseFloat(document.getElementById('purchasePrice').value) || 0;
var downPercent = parseFloat(document.getElementById('downPaymentPercent').value) || 0;
var interest = parseFloat(document.getElementById('interestRate').value) || 0;
var years = parseFloat(document.getElementById('loanTerm').value) || 30;
var rent = parseFloat(document.getElementById('monthlyRent').value) || 0;
var otherInc = parseFloat(document.getElementById('otherIncome').value) || 0;
var vacancyPercent = parseFloat(document.getElementById('vacancyRate').value) || 0;
var annualTax = parseFloat(document.getElementById('propertyTax').value) || 0;
var annualIns = parseFloat(document.getElementById('insurance').value) || 0;
var monthlyHOA = parseFloat(document.getElementById('hoa').value) || 0;
var maintPercent = parseFloat(document.getElementById('maintenance').value) || 0;
var mgmtPercent = parseFloat(document.getElementById('managementFee').value) || 0;
// 2. Calculate Mortgage (P&I)
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = (interest / 100) / 12;
var numberOfPayments = years * 12;
var monthlyMortgage = 0;
if (interest === 0) {
monthlyMortgage = loanAmount / numberOfPayments;
} else {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
// 3. Income Logic
var grossPotentialIncome = rent + otherInc;
var vacancyLoss = grossPotentialIncome * (vacancyPercent / 100);
var effectiveGrossIncome = grossPotentialIncome – vacancyLoss;
// 4. Expense Logic
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
var maintenanceCost = effectiveGrossIncome * (maintPercent / 100);
var managementCost = effectiveGrossIncome * (mgmtPercent / 100);
var totalOperatingExpenses = monthlyTax + monthlyIns + monthlyHOA + maintenanceCost + managementCost;
// 5. Profitability Metrics
var noiMonthly = effectiveGrossIncome – totalOperatingExpenses;
var cashFlow = noiMonthly – monthlyMortgage;
var annualCashFlow = cashFlow * 12;
var annualNOI = noiMonthly * 12;
// Initial investment usually includes closing costs, but we'll stick to down payment for simplicity unless added inputs exist
// Cap Rate = Annual NOI / Price
var capRate = (annualNOI / price) * 100;
// Cash on Cash = Annual Cash Flow / Total Cash Invested (Down Payment)
var cocReturn = 0;
if(downPaymentAmount > 0) {
cocReturn = (annualCashFlow / downPaymentAmount) * 100;
}
// 6. Display Results
var resultArea = document.getElementById('resultArea');
resultArea.style.display = "block";
document.getElementById('displayIncome').innerText = "$" + grossPotentialIncome.toFixed(2);
document.getElementById('displayVacancy').innerText = "-$" + vacancyLoss.toFixed(2);
document.getElementById('displayExpenses').innerText = "-$" + totalOperatingExpenses.toFixed(2);
document.getElementById('displayMortgage').innerText = "-$" + monthlyMortgage.toFixed(2);
var cashFlowEl = document.getElementById('displayCashFlow');
cashFlowEl.innerText = "$" + cashFlow.toFixed(2);
if (cashFlow >= 0) {
cashFlowEl.className = "highlight positive";
} else {
cashFlowEl.className = "highlight negative";
}
document.getElementById('displayNOI').innerText = "$" + Math.round(noiMonthly);
document.getElementById('displayCoC').innerText = cocReturn.toFixed(2) + "%";
document.getElementById('displayCap').innerText = capRate.toFixed(2) + "%";
}
Understanding Real Estate Cash Flow
Investing in rental properties is a powerful way to build wealth, but simply buying a property doesn't guarantee profit. The Rental Property Cash Flow Calculator helps you evaluate the math behind the deal before you make an offer. Cash flow is the net income from a real estate investment after mortgage payments and operating expenses have been made.
Why is Positive Cash Flow Critical?
Positive cash flow ensures that the property pays for itself. If a property has negative cash flow, you are essentially paying out of pocket every month to hold the asset. While some investors rely on appreciation (the property increasing in value over time), experienced investors prioritize cash flow to ensure sustainability during market downturns.
Key Metrics Explained
NOI (Net Operating Income): This is your annual income minus all operating expenses, but excluding mortgage payments. It measures the profitability of the property itself, regardless of how it is financed.
Cap Rate (Capitalization Rate): Calculated as NOI / Purchase Price. It represents the potential return on investment if you paid all cash. It helps compare properties across different markets.
Cash on Cash Return (CoC): Calculated as Annual Pre-Tax Cash Flow / Total Cash Invested. This is often the most important metric for leveraged investors because it tells you how hard your specific dollar is working for you.
Estimating Expenses Accurately
One of the biggest mistakes new investors make is underestimating expenses. This calculator includes fields for the "50% Rule" components:
Vacancy: Always account for the property sitting empty between tenants (typically 5-8%).
Maintenance/CapEx: Set aside 5-10% of rent for repairs (leaky faucets) and capital expenditures (new roof, HVAC).
Management Fees: Even if you self-manage, you should account for the value of your time (typically 8-10%).
How to Use This Calculator
Enter the purchase details, your expected financing terms, rental income, and detailed expenses. The tool will instantly provide the monthly cash flow, Cap Rate, and Cash on Cash return to help you make data-driven investment decisions.