Analyze your real estate investment deal instantly.
Purchase & Loan Details
Income & Expenses
Monthly Mortgage (P&I):$0.00
Total Monthly Expenses:$0.00
Net Operating Income (NOI) / Year:$0.00
Cap Rate:0.00%
Cash on Cash Return:0.00%
Monthly Cash Flow:$0.00
function calculateRentalCashFlow() {
// 1. Get Inputs
var price = parseFloat(document.getElementById('rpc_price').value) || 0;
var downPercent = parseFloat(document.getElementById('rpc_down_payment').value) || 0;
var interest = parseFloat(document.getElementById('rpc_interest').value) || 0;
var termYears = parseFloat(document.getElementById('rpc_term').value) || 0;
var closingCosts = parseFloat(document.getElementById('rpc_closing_costs').value) || 0;
var rent = parseFloat(document.getElementById('rpc_rent').value) || 0;
var taxYearly = parseFloat(document.getElementById('rpc_tax').value) || 0;
var insuranceYearly = parseFloat(document.getElementById('rpc_insurance').value) || 0;
var hoaMonthly = parseFloat(document.getElementById('rpc_hoa').value) || 0;
var maintPercent = parseFloat(document.getElementById('rpc_maintenance').value) || 0;
var vacancyPercent = parseFloat(document.getElementById('rpc_vacancy').value) || 0;
var managePercent = parseFloat(document.getElementById('rpc_management').value) || 0;
// 2. Loan Calculations
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyInterest = interest / 100 / 12;
var numberOfPayments = termYears * 12;
var monthlyMortgage = 0;
if (loanAmount > 0 && interest > 0) {
monthlyMortgage = loanAmount * (monthlyInterest * Math.pow(1 + monthlyInterest, numberOfPayments)) / (Math.pow(1 + monthlyInterest, numberOfPayments) – 1);
} else if (loanAmount > 0 && interest === 0) {
monthlyMortgage = loanAmount / numberOfPayments;
}
// 3. Expense Calculations (Monthly)
var taxMonthly = taxYearly / 12;
var insuranceMonthly = insuranceYearly / 12;
var maintMonthly = rent * (maintPercent / 100);
var vacancyMonthly = rent * (vacancyPercent / 100);
var manageMonthly = rent * (managePercent / 100);
var totalOpExpensesMonthly = taxMonthly + insuranceMonthly + hoaMonthly + maintMonthly + vacancyMonthly + manageMonthly;
var totalExpensesMonthly = totalOpExpensesMonthly + monthlyMortgage;
// 4. Returns Calculations
var monthlyCashFlow = rent – totalExpensesMonthly;
var annualCashFlow = monthlyCashFlow * 12;
// NOI = (Gross Income – Operating Expenses) * 12. Note: NOI excludes mortgage.
var monthlyNOI = rent – totalOpExpensesMonthly;
var annualNOI = monthlyNOI * 12;
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
var totalCashInvested = downPaymentAmount + closingCosts;
var cashOnCash = 0;
if (totalCashInvested > 0) {
cashOnCash = (annualCashFlow / totalCashInvested) * 100;
}
// 5. Formatting Helper
var formatCurrency = function(num) {
return '$' + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
};
// 6. Display Results
document.getElementById('res_mortgage').innerText = formatCurrency(monthlyMortgage);
document.getElementById('res_expenses').innerText = formatCurrency(totalExpensesMonthly);
document.getElementById('res_noi').innerText = formatCurrency(annualNOI);
document.getElementById('res_cap_rate').innerText = capRate.toFixed(2) + '%';
document.getElementById('res_coc').innerText = cashOnCash.toFixed(2) + '%';
document.getElementById('res_cashflow').innerText = formatCurrency(monthlyCashFlow);
// Change color of cashflow if negative
var cfElement = document.getElementById('res_cashflow');
if (monthlyCashFlow < 0) {
cfElement.style.color = '#e74c3c';
} else {
cfElement.style.color = '#2ecc71';
}
document.getElementById('rpc_results_box').style.display = 'block';
}
How to Analyze a Rental Property
Investing in real estate is one of the most reliable ways to build wealth, but simply buying a property and renting it out doesn't guarantee a profit. Successful investors rely on the math, not their gut feelings. This Rental Property Cash Flow Calculator is designed to help you objectively evaluate a potential deal by breaking down income, expenses, and return metrics.
Key Metrics Explained
1. Monthly Cash Flow
This is the most critical number for buy-and-hold investors. It represents the money left in your pocket after all expenses (mortgage, taxes, insurance, repairs) are paid. Positive cash flow ensures the property pays for itself and provides you with passive income. If this number is negative, you are subsidizing the property from your own pocket every month.
2. Net Operating Income (NOI)
NOI is calculated by subtracting all operating expenses from the total revenue generated by the property. Crucially, NOI excludes the mortgage payment. It is a pure measure of the property's profitability independent of financing structures. A higher NOI indicates a more profitable asset.
3. Cap Rate (Capitalization Rate)
The Cap Rate measures the natural rate of return of the property. It is calculated as (NOI / Purchase Price) × 100. It allows you to compare properties with different prices on an apples-to-apples basis. Generally, a higher Cap Rate implies a better return, though it may also come with higher risk (e.g., a property in a declining neighborhood).
4. Cash on Cash Return
While Cap Rate looks at the property, Cash on Cash Return looks at your specific investment. It is calculated as (Annual Cash Flow / Total Cash Invested) × 100. Since most investors use leverage (loans), this metric tells you how hard your actual down payment and closing costs are working for you. A 10-12% Cash on Cash return is often considered a strong target for rental investors.
Common Pitfalls to Avoid
Underestimating Vacancy: Always account for times when the property sits empty between tenants. A standard safe estimate is 5-8%.
Ignoring Maintenance: Roofs leak and water heaters break. Budgeting 5-10% of rent for repairs ensures you aren't caught off guard by large capital expenditures (CapEx).
Forgetting Property Management: Even if you plan to self-manage, you should account for the value of your time. If you eventually hire a manager, they typically charge 8-10% of the monthly rent.
Use the calculator above to adjust your offer price or down payment until the numbers align with your investment goals.