Analyze your real estate investment deal in seconds.
Purchase Details
Financing
Rental Income
Recurring Expenses
Investment Analysis
Monthly Principal & Interest:$0.00
Total Monthly Expenses:$0.00
Net Operating Income (NOI) / Month:$0.00
Monthly Cash Flow:$0.00
Cash on Cash Return (CoC):0.00%
Cap Rate:0.00%
function calculateRentalCashFlow() {
// 1. Get Inputs
var price = parseFloat(document.getElementById("rpcPrice").value);
var closingCosts = parseFloat(document.getElementById("rpcClosingCosts").value) || 0;
var downPaymentPercent = parseFloat(document.getElementById("rpcDownPayment").value);
var interestRate = parseFloat(document.getElementById("rpcInterestRate").value);
var loanTerm = parseFloat(document.getElementById("rpcTerm").value);
var rent = parseFloat(document.getElementById("rpcRent").value);
var annualTax = parseFloat(document.getElementById("rpcTax").value) || 0;
var annualInsurance = parseFloat(document.getElementById("rpcInsurance").value) || 0;
var monthlyHoa = parseFloat(document.getElementById("rpcHoa").value) || 0;
var maintPercent = parseFloat(document.getElementById("rpcMaint").value) || 0;
var vacancyPercent = parseFloat(document.getElementById("rpcVacancy").value) || 0;
var mgmtPercent = parseFloat(document.getElementById("rpcMgmt").value) || 0;
// Validation
if (isNaN(price) || isNaN(downPaymentPercent) || isNaN(interestRate) || isNaN(loanTerm) || isNaN(rent)) {
alert("Please fill in all required fields (Purchase Price, Down Payment, Rate, Term, and Rent).");
return;
}
// 2. Loan Calculations
var downPaymentAmount = price * (downPaymentPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = (interestRate / 100) / 12;
var numPayments = loanTerm * 12;
var monthlyPI = 0;
if (interestRate === 0) {
monthlyPI = loanAmount / numPayments;
} else {
monthlyPI = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
}
// 3. Operating Expenses Calculations
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
var monthlyMaint = rent * (maintPercent / 100);
var monthlyVacancy = rent * (vacancyPercent / 100);
var monthlyMgmt = rent * (mgmtPercent / 100);
// Total Operational Costs (excluding mortgage)
var monthlyOpEx = monthlyTax + monthlyInsurance + monthlyHoa + monthlyMaint + monthlyVacancy + monthlyMgmt;
// Total Expenses (including mortgage)
var totalMonthlyExpenses = monthlyPI + monthlyOpEx;
// 4. Metrics Calculations
var monthlyCashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
var totalCashInvested = downPaymentAmount + closingCosts;
// Net Operating Income (NOI) = Rent – Operating Expenses (No Mortgage)
var monthlyNOI = rent – monthlyOpEx;
var annualNOI = monthlyNOI * 12;
// Cap Rate = (Annual NOI / Purchase Price) * 100
var capRate = (annualNOI / price) * 100;
// Cash on Cash Return = (Annual Cash Flow / Total Cash Invested) * 100
var cocReturn = 0;
if (totalCashInvested > 0) {
cocReturn = (annualCashFlow / totalCashInvested) * 100;
}
// 5. Display Results
document.getElementById("rpcResults").style.display = "block";
document.getElementById("resMortgage").innerText = "$" + monthlyPI.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("resExpenses").innerText = "$" + totalMonthlyExpenses.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("resNOI").innerText = "$" + monthlyNOI.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
var cfElement = document.getElementById("resCashFlow");
cfElement.innerText = "$" + monthlyCashFlow.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
if (monthlyCashFlow < 0) {
cfElement.classList.add("rpc-negative");
cfElement.classList.remove("rpc-highlight");
} else {
cfElement.classList.remove("rpc-negative");
cfElement.classList.add("rpc-highlight");
}
document.getElementById("resCoC").innerText = cocReturn.toFixed(2) + "%";
document.getElementById("resCapRate").innerText = capRate.toFixed(2) + "%";
}
Why Use a Rental Property Cash Flow Calculator?
Investing in real estate is one of the most reliable ways to build long-term wealth, but it isn't without risk. The difference between a profitable asset and a money pit often comes down to the math. A Rental Property Cash Flow Calculator is an essential tool for investors to evaluate the viability of a potential purchase before signing any contracts.
By inputting specific data points like purchase price, financing terms, rental income, and detailed expenses, you can determine if a property will generate positive cash flow every month or if it will cost you money to hold.
Understanding Key Real Estate Metrics
This calculator provides several critical outputs that help you judge the quality of a deal. Here is what they mean:
1. Monthly Cash Flow
This is the most immediate metric for buy-and-hold investors. It represents the money left over after all expenses—including the mortgage, taxes, insurance, and maintenance reserves—are paid. A positive cash flow means the property pays for itself and provides you with income.
Formula: Gross Rent – Total Monthly Expenses = Cash Flow
2. Cash on Cash Return (CoC)
While cash flow tells you the dollar amount you earn, the Cash on Cash Return tells you how hard your money is working. It measures the annual return on the actual cash you invested (down payment + closing costs), not the total loan amount. This allows you to compare real estate returns against other investments like stocks or bonds.
Example: If you invest $50,000 cash to buy a property and it generates $5,000 in annual profit, your CoC is 10%.
3. Cap Rate (Capitalization Rate)
The Cap Rate measures the property's natural rate of return assuming you paid all cash (no loan). It is calculated by dividing the Net Operating Income (NOI) by the property's purchase price. This metric is crucial for comparing the profitability of similar properties regardless of how they are financed.
Common Expenses Investors Overlook
When using this calculator, accuracy is key. Many beginners fail because they underestimate expenses. Ensure you account for:
Vacancy Rates: Your property won't be rented 365 days a year. Budgeting 5-8% for vacancy ensures you have a buffer during turnover.
Maintenance & Repairs: Even new homes need repairs. Setting aside 5-10% of the rent prevents one broken water heater from destroying your annual profit.
Property Management: If you don't plan to be a landlord answering calls at midnight, budget 8-10% for a professional management company.
How to Interpret Your Results
If the Monthly Cash Flow is negative, the property is a liability. You will need to feed it money every month. Unless you are banking on massive appreciation (which is speculative), this is generally a bad deal for a beginner.
If the Cash on Cash Return is lower than inflation or safe stock market index funds (e.g., under 4-6%), the risk of owning real estate might not be justified. Most investors aim for a CoC return of 8-12% or higher.