function calculateCashFlow() {
// Get Inputs
var price = parseFloat(document.getElementById("purchasePrice").value);
var downPercent = parseFloat(document.getElementById("downPayment").value);
var rate = parseFloat(document.getElementById("interestRate").value);
var termYears = parseFloat(document.getElementById("loanTerm").value);
var rent = parseFloat(document.getElementById("monthlyRent").value);
var expenses = parseFloat(document.getElementById("monthlyExpenses").value);
// Validation
if (isNaN(price) || isNaN(downPercent) || isNaN(rate) || isNaN(termYears) || isNaN(rent) || isNaN(expenses)) {
alert("Please fill in all fields with valid numbers.");
return;
}
// Calculations
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = (rate / 100) / 12;
var totalMonths = termYears * 12;
// Mortgage P&I Calculation
var monthlyMortgage = 0;
if (rate > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalMonths)) / (Math.pow(1 + monthlyRate, totalMonths) – 1);
} else {
monthlyMortgage = loanAmount / totalMonths;
}
var totalMonthlyCosts = monthlyMortgage + expenses;
var monthlyCashFlow = rent – totalMonthlyCosts;
var annualCashFlow = monthlyCashFlow * 12;
// Net Operating Income (NOI) = (Rent – Operating Expenses) * 12
// Note: Mortgage P&I is NOT included in operating expenses for NOI calculation
var noi = (rent – expenses) * 12;
// Cap Rate = (NOI / Purchase Price) * 100
var capRate = (noi / price) * 100;
// Cash on Cash Return = (Annual Cash Flow / Total Cash Invested) * 100
// Assuming Total Cash Invested = Down Payment for this simplified version
var cashInvested = downPaymentAmount;
var cocReturn = 0;
if (cashInvested > 0) {
cocReturn = (annualCashFlow / cashInvested) * 100;
}
// Update DOM
document.getElementById("resMortgage").innerText = "$" + monthlyMortgage.toFixed(2);
document.getElementById("resTotalCosts").innerText = "$" + totalMonthlyCosts.toFixed(2);
var flowEl = document.getElementById("resCashFlow");
flowEl.innerText = "$" + monthlyCashFlow.toFixed(2);
if(monthlyCashFlow >= 0) {
flowEl.className = "result-value positive-flow";
} else {
flowEl.className = "result-value negative-flow";
}
document.getElementById("resNOI").innerText = "$" + noi.toFixed(2);
document.getElementById("resCapRate").innerText = capRate.toFixed(2) + "%";
document.getElementById("resCoC").innerText = cocReturn.toFixed(2) + "%";
document.getElementById("results").style.display = "block";
}
Understanding Rental Property Cash Flow
Investing in real estate is a powerful way to build wealth, but simply buying a property doesn't guarantee a profit. The Rental Property Cash Flow Calculator helps investors analyze potential deals to ensure they generate positive income.
What is Cash Flow in Real Estate?
Cash flow represents the net amount of money moving into and out of a rental property business. In simple terms, it is the money left over after all expenses—including the mortgage, taxes, insurance, and maintenance—have been paid from the monthly rental income.
Positive Cash Flow: You earn more in rent than you spend on expenses. This is the goal for most buy-and-hold investors. Negative Cash Flow: The property costs more to operate than it brings in. This typically requires the investor to feed money into the property monthly.
Key Metrics Explained
1. Net Operating Income (NOI)
NOI is a fundamental calculation used to analyze the profitability of income-generating real estate investments. It equals all revenue from the property, minus all necessary operating expenses. Importantly, NOI excludes mortgage payments (Principal and Interest).
Formula:NOI = Annual Rent - Operating Expenses
2. Capitalization Rate (Cap Rate)
The Cap Rate indicates the potential rate of return on an investment property assuming it was bought with all cash (no loan). It helps compare properties regardless of financing.
Formula:Cap Rate = (NOI / Purchase Price) x 100
A "good" Cap Rate varies by market, but generally, 4% to 10% is considered acceptable, with higher percentages representing higher potential returns (and often higher risk).
3. Cash on Cash Return
This metric is crucial for investors using financing. It measures the annual return made on the actual cash invested (down payment and closing costs).
Formula:Cash on Cash = (Annual Cash Flow / Total Cash Invested) x 100
How to Improve Rental Cash Flow
Increase Rent: Keeping up with market rates ensures your income maximizes potential.
Reduce Vacancy: Long-term tenants reduce turnover costs and lost income months.
Refinance: Securing a lower interest rate can significantly drop your monthly mortgage payment.
Appeal Property Taxes: If your assessment is too high, appealing it can lower your annual tax bill.
Frequently Asked Questions
What is the 1% Rule?
The 1% rule is a quick screening tool. It suggests that the monthly rent should be at least 1% of the purchase price. For example, a $200,000 home should rent for at least $2,000/month. While not a hard rule, it often indicates strong cash flow potential.
Should I calculate maintenance costs?
Yes. Even if a property is new, things break. It is prudent to budget 5% to 10% of the monthly rent for maintenance and capital expenditures (CapEx) like a new roof or HVAC system.
Does this calculator include depreciation?
No. This calculator focuses on liquid cash flow. Depreciation is a non-cash tax deduction that can save you money at tax time, but it does not put cash in your pocket monthly.