Rental Property Cash Flow Calculator
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Rental Property Cash Flow Calculator
function calculateCashFlow() {
// 1. Get input values
var price = parseFloat(document.getElementById("propPrice").value);
var downPercent = parseFloat(document.getElementById("downPaymentPercent").value);
var rate = parseFloat(document.getElementById("interestRate").value);
var years = parseFloat(document.getElementById("loanTerm").value);
var rent = parseFloat(document.getElementById("monthlyRent").value);
var tax = parseFloat(document.getElementById("annualTax").value);
var insurance = parseFloat(document.getElementById("annualInsurance").value);
var vacancyRate = parseFloat(document.getElementById("repairVacancy").value);
// Validation to prevent NaN
if (isNaN(price) || isNaN(rent) || isNaN(rate) || isNaN(years)) {
alert("Please enter valid numbers in all fields.");
return;
}
// 2. Calculate Mortgage (Principal and Interest)
var downPayment = price * (downPercent / 100);
var loanAmount = price – downPayment;
var monthlyRate = (rate / 100) / 12;
var totalPayments = years * 12;
var monthlyMortgage = 0;
if (rate > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalPayments)) / (Math.pow(1 + monthlyRate, totalPayments) – 1);
} else {
monthlyMortgage = loanAmount / totalPayments;
}
// 3. Calculate Monthly Expenses
var monthlyTax = tax / 12;
var monthlyIns = insurance / 12;
var monthlyVacancyRepairs = rent * (vacancyRate / 100);
var totalMonthlyExpenses = monthlyMortgage + monthlyTax + monthlyIns + monthlyVacancyRepairs;
var operatingExpenses = monthlyTax + monthlyIns + monthlyVacancyRepairs; // Excludes mortgage
// 4. Calculate Key Metrics
var monthlyCashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
var monthlyNOI = rent – operatingExpenses;
var annualNOI = monthlyNOI * 12;
// Cash on Cash Return = Annual Cash Flow / Total Cash Invested (Down Payment)
// Simplified: Assuming closing costs are negligible or part of down payment for this basic calc
var cashOnCash = 0;
if (downPayment > 0) {
cashOnCash = (annualCashFlow / downPayment) * 100;
}
// Cap Rate = Annual NOI / Purchase Price
var capRate = (annualNOI / price) * 100;
// 5. Update UI
document.getElementById("displayMortgage").innerText = "$" + monthlyMortgage.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("displayExpenses").innerText = "$" + totalMonthlyExpenses.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("displayNOI").innerText = "$" + monthlyNOI.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
var cfElement = document.getElementById("displayCashFlow");
cfElement.innerText = "$" + monthlyCashFlow.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
if (monthlyCashFlow >= 0) {
cfElement.className = "result-value positive-flow";
} else {
cfElement.className = "result-value negative-flow";
}
document.getElementById("displayCoC").innerText = cashOnCash.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}) + "%";
document.getElementById("displayCapRate").innerText = capRate.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}) + "%";
document.getElementById("results-area").style.display = "block";
}
Understanding Rental Property Cash Flow
Calculating the cash flow of a rental property is the single most important step in real estate investing. It determines whether a potential investment will put money in your pocket every month or become a financial burden. This Rental Property Cash Flow Calculator helps investors analyze deals by factoring in mortgages, taxes, insurance, and maintenance costs.
What is Positive Cash Flow?
Positive cash flow occurs when a property's monthly income (rent) exceeds its monthly expenses (mortgage, taxes, insurance, and repairs). For example, if you collect $2,200 in rent and your total expenses are $1,800, your positive cash flow is $400 per month.
Key Metrics Explained
- NOI (Net Operating Income): This is the total income minus operating expenses (taxes, insurance, maintenance) before paying the mortgage. It is a pure measure of the property's efficiency.
- Cash on Cash Return (CoC): This percentage tells you how hard your money is working. It compares your annual cash flow to the actual cash you invested (down payment). A CoC of 8-12% is often considered a solid return in real estate.
- Cap Rate (Capitalization Rate): This measures the rate of return on a real estate investment property based on the income that the property is expected to generate. It is calculated by dividing the NOI by the property value.
How to Estimate Expenses Accurately
Novice investors often underestimate expenses. When using this calculator, ensure you account for:
- Vacancy Rate: Properties are rarely occupied 100% of the time. A standard "safety" number is 5% to 8% of the rent.
- Maintenance & CapEx: Roofs leak and water heaters break. Setting aside 10% of the monthly rent for repairs is a prudent strategy to avoid cash flow shock.
- Property Management: Even if you self-manage now, calculating a 10% management fee helps ensure the deal still works if you hire a manager later.
Why Use This Calculator?
Real estate markets fluctuate, but the math behind a profitable rental remains constant. By inputting accurate data into the fields above—specifically interest rates and realistic rent estimates—you can filter out bad deals quickly. Always aim for a buffer in your cash flow calculations to handle unexpected vacancies or economic shifts.