Please enter valid positive numbers for all fields.
Financial Analysis
Monthly Cash Flow:$0.00
Cash on Cash Return (CoC):0.00%
Cap Rate:0.00%
Net Operating Income (NOI) / Month:$0.00
Monthly Mortgage Payment:$0.00
Total Monthly Expenses (inc. Mortgage):$0.00
function calculateRental() {
// 1. Retrieve Inputs
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPerc = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var term = parseFloat(document.getElementById('loanTerm').value);
var closing = parseFloat(document.getElementById('closingCosts').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var taxYear = parseFloat(document.getElementById('propTax').value);
var insYear = parseFloat(document.getElementById('insurance').value);
var maintPerc = parseFloat(document.getElementById('maintenance').value);
var vacPerc = parseFloat(document.getElementById('vacancy').value);
// 2. Validation
if (isNaN(price) || isNaN(downPerc) || isNaN(rate) || isNaN(term) || isNaN(rent) ||
isNaN(taxYear) || isNaN(insYear) || isNaN(maintPerc) || isNaN(vacPerc)) {
document.getElementById('errorMsg').style.display = 'block';
document.getElementById('results').style.display = 'none';
return;
}
document.getElementById('errorMsg').style.display = 'none';
// 3. Calculation Logic
// Loan Calculations
var downAmount = price * (downPerc / 100);
var loanAmount = price – downAmount;
var monthlyRate = rate / 100 / 12;
var numberOfPayments = term * 12;
// Mortgage Payment Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyMortgage = 0;
if (rate > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
} else {
monthlyMortgage = loanAmount / numberOfPayments;
}
// Monthly Expense Calculations
var monthlyTax = taxYear / 12;
var monthlyIns = insYear / 12;
var monthlyMaint = rent * (maintPerc / 100);
var monthlyVac = rent * (vacPerc / 100);
var operatingExpenses = monthlyTax + monthlyIns + monthlyMaint + monthlyVac;
var totalMonthlyExpenses = operatingExpenses + monthlyMortgage;
// Metrics
var monthlyNOI = rent – operatingExpenses;
var monthlyCashFlow = monthlyNOI – monthlyMortgage;
var annualCashFlow = monthlyCashFlow * 12;
var annualNOI = monthlyNOI * 12;
var totalCashInvested = downAmount + closing;
// Return Metrics
var coc = 0;
if (totalCashInvested > 0) {
coc = (annualCashFlow / totalCashInvested) * 100;
}
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
// 4. Update UI
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 ? '#28a745' : '#dc3545';
document.getElementById('resCoC').innerText = coc.toFixed(2) + '%';
document.getElementById('resCapRate').innerText = capRate.toFixed(2) + '%';
document.getElementById('resNOI').innerText = formatter.format(monthlyNOI);
document.getElementById('resMortgage').innerText = formatter.format(monthlyMortgage);
document.getElementById('resTotalExp').innerText = formatter.format(totalMonthlyExpenses);
document.getElementById('results').style.display = 'block';
}
Mastering Rental Property Analysis
Investing in real estate is one of the most reliable ways to build long-term wealth, but success hinges on the numbers. Whether you are a seasoned investor or buying your first duplex, understanding the cash flow of a potential property is non-negotiable. This Rental Property Cash Flow Calculator helps you determine if a deal is a "cash cow" or a money pit.
Why Cash Flow Matters More Than Appreciation
Many novice investors speculate on home values rising (appreciation). While appreciation is a great bonus, cash flow is what keeps you in business. Cash flow is the net profit you pocket every month after all operating expenses and mortgage payments are made. Positive cash flow ensures the property pays for itself and provides you with passive income.
Key Metrics Defined
Our calculator provides several critical metrics to evaluate your investment:
Net Operating Income (NOI): This is your total income minus operating expenses (taxes, insurance, repairs, vacancy) before paying the mortgage. It measures the profitability of the property itself, excluding financing costs.
Cash Flow: The actual money remaining after the mortgage (debt service) is paid from the NOI. If this number is negative, you are losing money every month.
Cash on Cash Return (CoC): This measures the return on the actual cash you invested (down payment + closing costs). It is calculated as Annual Cash Flow / Total Cash Invested. A CoC of 8-12% is often considered a solid benchmark for rental properties.
Cap Rate: The rate of return on the property assuming you bought it in all cash. It helps compare properties regardless of how they are financed.
How to Estimate Expenses
Underestimating expenses is the #1 mistake investors make. Use these guidelines when filling out the calculator:
Vacancy Rate: Always assume the property will be empty sometimes. A standard safe estimate is 5% to 8% (roughly 2-4 weeks per year).
Maintenance: Even if the house is new, things break. Set aside 5% to 10% of the rent for future repairs.
Property Management: If you hire a manager, they typically charge 8-10% of the monthly rent. Even if you self-manage now, it's wise to factor this in to see if the deal still works if you decide to outsource later.
Interpreting Your Results
If your Cash Flow is positive (e.g., $200+/month per door), the asset is generating income. If it is negative, you must rely on appreciation to make a profit, which is risky. A healthy Cash on Cash Return usually beats the stock market average (7-8%), justifying the extra effort involved in real estate investing.