Analyze the profitability of your real estate investment.
Purchase Information
Income & Expenses (Monthly/Yearly)
Operating Assumptions
Monthly Mortgage (P&I):$0.00
Total Monthly Expenses:$0.00
Net Operating Income (NOI):$0.00
Monthly Cash Flow:$0.00
Cash on Cash Return:0.00%
Cap Rate:0.00%
function calculateRental() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('rpc_price').value);
var downPercent = parseFloat(document.getElementById('rpc_down_percent').value);
var rate = parseFloat(document.getElementById('rpc_rate').value);
var term = parseFloat(document.getElementById('rpc_term').value);
var rent = parseFloat(document.getElementById('rpc_rent').value);
var taxYearly = parseFloat(document.getElementById('rpc_tax').value);
var insYearly = parseFloat(document.getElementById('rpc_insurance').value);
var hoaMonthly = parseFloat(document.getElementById('rpc_hoa').value);
var vacancyRate = parseFloat(document.getElementById('rpc_vacancy').value);
var maintRate = parseFloat(document.getElementById('rpc_maintenance').value);
var mgmtRate = parseFloat(document.getElementById('rpc_mgmt').value);
var closingCosts = parseFloat(document.getElementById('rpc_closing').value);
// Validate inputs
if (isNaN(price) || isNaN(rent) || isNaN(rate)) {
alert("Please enter valid numbers for Price, Rent, and Interest Rate.");
return;
}
// Handle defaults for empty optional fields
if (isNaN(hoaMonthly)) hoaMonthly = 0;
if (isNaN(closingCosts)) closingCosts = 0;
// 2. Calculate Mortgage (P&I)
var downPayment = price * (downPercent / 100);
var loanAmount = price – downPayment;
var monthlyRate = (rate / 100) / 12;
var totalPayments = term * 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 Operating Expenses
// Variable expenses based on rent
var vacancyCost = rent * (vacancyRate / 100);
var maintCost = rent * (maintRate / 100);
var mgmtCost = rent * (mgmtRate / 100);
// Fixed expenses
var taxMonthly = taxYearly / 12;
var insMonthly = insYearly / 12;
var totalOperatingExpenses = taxMonthly + insMonthly + hoaMonthly + vacancyCost + maintCost + mgmtCost;
var totalExpensesWithMortgage = totalOperatingExpenses + monthlyMortgage;
// 4. Calculate Metrics
var noiMonthly = rent – totalOperatingExpenses;
var cashFlowMonthly = noiMonthly – monthlyMortgage;
var cashFlowYearly = cashFlowMonthly * 12;
var totalCashInvested = downPayment + closingCosts;
var cashOnCash = 0;
if (totalCashInvested > 0) {
cashOnCash = (cashFlowYearly / totalCashInvested) * 100;
}
var capRate = ((noiMonthly * 12) / price) * 100;
// 5. Update DOM
document.getElementById('rpc_results').style.display = 'block';
// Format Currency Function
var fmtMoney = new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' });
var fmtPct = new Intl.NumberFormat('en-US', { style: 'percent', minimumFractionDigits: 2, maximumFractionDigits: 2 });
document.getElementById('res_mortgage').innerHTML = fmtMoney.format(monthlyMortgage);
document.getElementById('res_expenses').innerHTML = fmtMoney.format(totalOperatingExpenses); // Excluding mortgage for definition of OpEx usually, but let's be clear
document.getElementById('res_noi').innerHTML = fmtMoney.format(noiMonthly);
var cfEl = document.getElementById('res_cashflow');
cfEl.innerHTML = fmtMoney.format(cashFlowMonthly);
cfEl.className = "result-val " + (cashFlowMonthly >= 0 ? "positive" : "negative");
var cocEl = document.getElementById('res_coc');
cocEl.innerHTML = cashOnCash.toFixed(2) + "%";
cocEl.className = "result-val " + (cashOnCash >= 0 ? "positive" : "negative");
document.getElementById('res_cap').innerHTML = capRate.toFixed(2) + "%";
}
Understanding Rental Property Cash Flow
Investing in real estate is one of the most reliable ways to build wealth, but not every property is a good investment. The difference between a profitable asset and a money pit often comes down to one metric: Cash Flow. This calculator helps investors analyze potential rental properties by accounting for all income and expenses, providing a realistic picture of your potential returns.
What is Positive Cash Flow?
Positive cash flow occurs when a property's gross annual income exceeds its total operating expenses and debt service (mortgage payments). In simple terms, it is the profit you pocket every month after all bills are paid.
This calculator outputs three critical metrics to help you make informed decisions:
1. Net Operating Income (NOI)
NOI is the annual income generated by an income-producing property after deducting all operating expenses but before deducting taxes and financing costs. It helps determine the intrinsic value of the property regardless of how it is financed.
2. Cash on Cash Return (CoC)
This is arguably the most important metric for investors. It measures the annual return you made on the property in relation to the amount of mortgage paid during the same year. It tells you how hard your actual cash investment is working for you.
Good CoC: Generally, 8-12% is considered solid, while anything above 15% is excellent.
Calculation: (Annual Pre-Tax Cash Flow / Total Cash Invested) x 100
3. Cap Rate (Capitalization Rate)
The Cap Rate indicates the rate of return that is expected to be generated on a real estate investment property. It is calculated by dividing the Net Operating Income by the property asset value.
Common Operating Expenses to Watch
Many new investors overestimate their profit by ignoring hidden costs. Ensure you account for:
Vacancy Rates: Properties won't be rented 365 days a year. A 5-8% vacancy allowance is standard.
Maintenance & Repairs: Budgeting 1% of the property value per year or 5-10% of rent is a prudent safeguard against broken appliances or roof leaks.
Property Management: If you don't plan to be a landlord, expect to pay a management company 8-10% of the monthly rent.
Capital Expenditures (CapEx): Large expenses like HVAC replacement or new roofing that occur infrequently but are costly.
How to Use This Calculator
To get the most accurate result, do not guess on the expense figures. Call local insurance agents for quotes, check property tax records (often public), and look at comparable rentals in the area (comps) to validate your rental income assumptions. By inputting accurate data into the fields above, you can confidently identify properties that meet your financial goals.