Success in real estate investing hinges on one critical metric: Cash Flow. This Rental Property Cash Flow Calculator helps investors analyze potential deals by estimating monthly income, operating expenses, and financing costs to determine the net profit a property generates each month.
Whether you are analyzing a single-family home, a duplex, or a condo, input your purchase details below to calculate your Cash-on-Cash Return (CoC) and Capitalization Rate (Cap Rate).
30 Years
15 Years
10 Years
Analysis Results
Monthly Cash Flow:$0.00
Cash on Cash Return (ROI):0.00%
Cap Rate:0.00%
Total Monthly Income:$0.00
Monthly Mortgage (P&I):$0.00
Total Monthly Expenses:$0.00
NOI (Net Operating Income):$0.00
function calculateRentalCashFlow() {
// Get Input Values
var price = parseFloat(document.getElementById("purchasePrice").value) || 0;
var rent = parseFloat(document.getElementById("monthlyRent").value) || 0;
var downPercent = parseFloat(document.getElementById("downPaymentPercent").value) || 0;
var interest = parseFloat(document.getElementById("interestRate").value) || 0;
var term = parseInt(document.getElementById("loanTerm").value) || 30;
var tax = parseFloat(document.getElementById("annualPropertyTax").value) || 0;
var insurance = parseFloat(document.getElementById("annualInsurance").value) || 0;
var hoa = parseFloat(document.getElementById("hoaFees").value) || 0;
var maintRate = parseFloat(document.getElementById("maintenanceRate").value) || 0;
var vacancyRate = parseFloat(document.getElementById("vacancyRate").value) || 0;
var mgmtRate = parseFloat(document.getElementById("managementFee").value) || 0;
var closingCosts = parseFloat(document.getElementById("closingCosts").value) || 0;
// Calculations
// 1. Initial Investment
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var totalInitialCash = downPaymentAmount + closingCosts;
// 2. Mortgage Payment (P&I)
var monthlyRate = interest / 100 / 12;
var numPayments = term * 12;
var mortgagePayment = 0;
if (interest > 0) {
mortgagePayment = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
} else {
mortgagePayment = loanAmount / numPayments;
}
// 3. Operating Income (Adjusted for Vacancy)
var vacancyCost = rent * (vacancyRate / 100);
var effectiveIncome = rent – vacancyCost;
// 4. Monthly Expenses
var monthlyTax = tax / 12;
var monthlyInsurance = insurance / 12;
var maintenanceCost = rent * (maintRate / 100);
var mgmtCost = rent * (mgmtRate / 100);
// NOI Expenses does not include Mortgage
var operatingExpenses = monthlyTax + monthlyInsurance + hoa + maintenanceCost + mgmtCost;
// Total Expenses includes Mortgage
var totalMonthlyExpenses = operatingExpenses + mortgagePayment;
// 5. Cash Flow
var monthlyCashFlow = effectiveIncome – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// 6. Returns
var noi = (effectiveIncome – operatingExpenses) * 12; // Annual NOI
var capRate = (price > 0) ? (noi / price) * 100 : 0;
var cocReturn = (totalInitialCash > 0) ? (annualCashFlow / totalInitialCash) * 100 : 0;
// Display Results
document.getElementById("resultsArea").style.display = "block";
// Format Currency
var formatCurr = new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' });
var elCashFlow = document.getElementById("resMonthlyCashFlow");
elCashFlow.innerText = formatCurr.format(monthlyCashFlow);
if (monthlyCashFlow >= 0) {
elCashFlow.classList.remove("negative-cashflow");
elCashFlow.classList.add("positive-cashflow");
} else {
elCashFlow.classList.remove("positive-cashflow");
elCashFlow.classList.add("negative-cashflow");
}
document.getElementById("resCocReturn").innerText = cocReturn.toFixed(2) + "%";
document.getElementById("resCapRate").innerText = capRate.toFixed(2) + "%";
document.getElementById("resTotalIncome").innerText = formatCurr.format(effectiveIncome);
document.getElementById("resMortgage").innerText = formatCurr.format(mortgagePayment);
document.getElementById("resTotalExpenses").innerText = formatCurr.format(totalMonthlyExpenses);
document.getElementById("resNOI").innerText = formatCurr.format(noi / 12) + " /mo";
}
Understanding the Rental Property Cash Flow Formula
Calculating cash flow is the most objective way to assess an investment property's performance. It removes emotions from the decision-making process and focuses purely on the math.
1. Gross Income vs. Net Operating Income (NOI)
Many beginners mistake Gross Rental Income for profit. However, real life involves vacancies. Our calculator subtracts a Vacancy Rate (typically 5-8% depending on the market) to give you the Effective Gross Income.
Net Operating Income (NOI) is calculated by subtracting all operating expenses (Taxes, Insurance, HOA, Maintenance, Management) from the Effective Income. Note that NOI excludes mortgage payments.
2. The Role of the Mortgage
Leverage is a powerful tool in real estate. The Debt Service (your mortgage principal and interest) is the largest expense for most investors. This calculator uses a standard amortization formula to determine your exact monthly payment based on the loan term and interest rate.
3. Key Metrics: Cap Rate vs. Cash-on-Cash Return
Cap Rate (Capitalization Rate): Measures the natural rate of return of the property assuming you bought it in cash. It is calculated as Annual NOI / Purchase Price. A good Cap Rate is typically between 5% and 10%.
Cash-on-Cash Return (CoC): Measures the return on the actual cash you invested (Down Payment + Closing Costs). It is calculated as Annual Pre-Tax Cash Flow / Total Cash Invested. This is often the most important metric for investors using leverage.
How to Interpret Your Results
Positive Cash Flow: If the result is green, your property generates income after all expenses. This provides a safety net for repairs and passive income for your wallet.
Negative Cash Flow: If the result is red, the property costs you money every month to own. While some investors accept this in high-appreciation markets, it carries higher risk.
Example Scenario
If you purchase a property for $300,000 with 20% down ($60,000) and rent it for $2,500/month, your expenses (mortgage, tax, insurance, maintenance) might total $2,200. This leaves you with $300 monthly cash flow. While $300 seems small, your Cash-on-Cash return might be around 6%, which is often higher than a savings account, plus you benefit from principal paydown and appreciation.