Rental Property Cash Flow Calculator
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Investment Analysis
Monthly Cash Flow:
$0.00
Cash on Cash Return (CoC):
0.00%
Cap Rate:
0.00%
Net Operating Income (NOI Annual):
$0.00
Total Cash Needed to Close:
$0.00
Estimated Mortgage (P&I):
$0.00
Total Monthly Expenses:
$0.00
Understanding Rental Property Cash Flow
Calculating cash flow is the most critical step in evaluating a rental property investment. Positive cash flow ensures that the property pays for itself while generating income for the investor. This calculator helps you determine if a potential deal makes financial sense by analyzing all income and expense variables.
How is Cash Flow Calculated?
The basic formula for monthly cash flow is straightforward:
- Gross Income: Total rent collected plus any other income (laundry, parking, etc.).
- Operating Expenses: Costs to run the property, including taxes, insurance, HOA fees, maintenance, property management, and vacancy reserves.
- Debt Service: The monthly principal and interest payment on your mortgage.
Formula: Cash Flow = Gross Income – (Operating Expenses + Debt Service)
Key Metrics Explained
Cash on Cash Return (CoC)
This metric measures the annual return on the actual cash you invested. It is calculated by dividing the annual pre-tax cash flow by the total cash invested (down payment + closing costs + rehab costs).
Cap Rate (Capitalization Rate)
Cap rate measures the property's natural rate of return assuming you paid all cash. It helps compare properties regardless of financing. It is calculated as Net Operating Income (NOI) / Purchase Price.
Net Operating Income (NOI)
NOI calculates the profitability of the property before adding in mortgage costs. It is strictly Income minus Operating Expenses.
What is a Good Cash Flow?
While "good" is subjective, many investors look for:
- $100 – $300 per door: A standard minimum monthly profit for single-family homes.
- 8% – 12% CoC Return: A healthy return that typically beats the stock market average.
- The 1% Rule: A quick rule of thumb suggesting monthly rent should be at least 1% of the purchase price to likely be profitable.
function calculateCashFlow() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('purchasePrice').value) || 0;
var downPercent = parseFloat(document.getElementById('downPaymentPercent').value) || 0;
var closingCosts = parseFloat(document.getElementById('closingCosts').value) || 0;
var interestRate = parseFloat(document.getElementById('interestRate').value) || 0;
var termYears = parseFloat(document.getElementById('loanTerm').value) || 0;
var rent = parseFloat(document.getElementById('monthlyRent').value) || 0;
var yearlyTax = parseFloat(document.getElementById('propertyTax').value) || 0;
var yearlyInsurance = parseFloat(document.getElementById('insurance').value) || 0;
var monthlyHoa = parseFloat(document.getElementById('hoa').value) || 0;
var vacancyRate = parseFloat(document.getElementById('vacancy').value) || 0;
var maintenanceRate = parseFloat(document.getElementById('maintenance').value) || 0;
// 2. Calculate Loan Details
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyInterestRate = (interestRate / 100) / 12;
var numberOfPayments = termYears * 12;
// Mortgage Calculation (Principal & Interest)
var monthlyMortgage = 0;
if (loanAmount > 0 && interestRate > 0) {
monthlyMortgage = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
} else if (loanAmount > 0 && interestRate === 0) {
monthlyMortgage = loanAmount / numberOfPayments;
}
// 3. Calculate Monthly Expenses
var monthlyTax = yearlyTax / 12;
var monthlyInsurance = yearlyInsurance / 12;
var vacancyCost = rent * (vacancyRate / 100);
var maintenanceCost = rent * (maintenanceRate / 100);
// Total Operating Expenses (Excluding Mortgage)
var monthlyOperatingExpenses = monthlyTax + monthlyInsurance + monthlyHoa + vacancyCost + maintenanceCost;
// Total Monthly Expenses (Including Mortgage)
var totalMonthlyExpenses = monthlyOperatingExpenses + monthlyMortgage;
// 4. Calculate Key Metrics
// Cash Flow
var monthlyCashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// Net Operating Income (NOI) – Annual
var monthlyNOI = rent – monthlyOperatingExpenses;
var annualNOI = monthlyNOI * 12;
// Cash on Cash Return
var totalCashInvested = downPaymentAmount + closingCosts;
var cashOnCash = 0;
if (totalCashInvested > 0) {
cashOnCash = (annualCashFlow / totalCashInvested) * 100;
}
// Cap Rate
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
// 5. Update DOM
document.getElementById('results-area').style.display = 'block';
// Format Currency Function
var fmtMoney = new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' });
// Set Values
var cfElement = document.getElementById('resMonthlyCashFlow');
cfElement.innerText = fmtMoney.format(monthlyCashFlow);
if(monthlyCashFlow >= 0) {
cfElement.className = "result-value cash-flow-positive";
} else {
cfElement.className = "result-value cash-flow-negative";
}
document.getElementById('resCoc').innerText = cashOnCash.toFixed(2) + "%";
document.getElementById('resCapRate').innerText = capRate.toFixed(2) + "%";
document.getElementById('resNoi').innerText = fmtMoney.format(annualNOI);
document.getElementById('resCashNeeded').innerText = fmtMoney.format(totalCashInvested);
document.getElementById('resMortgage').innerText = fmtMoney.format(monthlyMortgage);
document.getElementById('resTotalExp').innerText = fmtMoney.format(totalMonthlyExpenses);
}