Analyze your real estate investment performance instantly.
Purchase & Loan Details
Income & Expenses
Investment Analysis
Monthly Cash Flow:$0.00
Cash on Cash Return (CoC):0.00%
Cap Rate:0.00%
Net Operating Income (NOI / Year):$0.00
Total Monthly Expenses:$0.00
Monthly Mortgage Payment:$0.00
function calculateRentalCashFlow() {
// 1. Get Inputs
var price = parseFloat(document.getElementById('rp_price').value);
var downPercent = parseFloat(document.getElementById('rp_down').value);
var rate = parseFloat(document.getElementById('rp_rate').value);
var term = parseFloat(document.getElementById('rp_term').value);
var rent = parseFloat(document.getElementById('rp_rent').value);
var vacancyPercent = parseFloat(document.getElementById('rp_vacancy').value);
var taxYearly = parseFloat(document.getElementById('rp_tax').value);
var insuranceYearly = parseFloat(document.getElementById('rp_insurance').value);
var maintPercent = parseFloat(document.getElementById('rp_main').value);
var hoaMonthly = parseFloat(document.getElementById('rp_hoa').value);
// Validation
if (isNaN(price) || isNaN(rent) || isNaN(rate) || isNaN(term)) {
alert("Please enter valid numbers for Price, Rent, Interest Rate, and Term.");
return;
}
// 2. Calculations
// Loan Calculation
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = rate / 100 / 12;
var numberOfPayments = term * 12;
var monthlyMortgage = 0;
if (rate > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
} else {
monthlyMortgage = loanAmount / numberOfPayments;
}
// Income adjustments
var vacancyCost = rent * (vacancyPercent / 100);
var effectiveGrossIncome = rent – vacancyCost;
// Operating Expenses (Monthly)
var taxMonthly = taxYearly / 12;
var insuranceMonthly = insuranceYearly / 12;
var maintMonthly = rent * (maintPercent / 100);
var operatingExpenses = taxMonthly + insuranceMonthly + maintMonthly + hoaMonthly;
// Total Expenses (including mortgage)
var totalMonthlyExpenses = operatingExpenses + monthlyMortgage;
// Cash Flow
var monthlyCashFlow = effectiveGrossIncome – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// NOI (Net Operating Income) – Annual
// NOI = Annual Gross Income – Operating Expenses (NOT including mortgage)
var annualNOI = (effectiveGrossIncome * 12) – (operatingExpenses * 12);
// Cap Rate
var capRate = (annualNOI / price) * 100;
// Cash on Cash Return
// Assuming Cash Invested is just the down payment for this simplified calculator
// Ideally should include closing costs, but we stick to inputs provided
var cashInvested = downPaymentAmount;
var cashOnCash = 0;
if (cashInvested > 0) {
cashOnCash = (annualCashFlow / cashInvested) * 100;
}
// 3. Display Results
var resultBox = document.getElementById('rp_result_box');
resultBox.style.display = 'block';
// Helper for currency formatting
var fmt = new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' });
document.getElementById('res_cashflow').innerText = fmt.format(monthlyCashFlow);
document.getElementById('res_coc').innerText = cashOnCash.toFixed(2) + "%";
document.getElementById('res_cap').innerText = capRate.toFixed(2) + "%";
document.getElementById('res_noi').innerText = fmt.format(annualNOI);
document.getElementById('res_expenses').innerText = fmt.format(totalMonthlyExpenses);
document.getElementById('res_mortgage').innerText = fmt.format(monthlyMortgage);
// Color coding for Cash Flow
var cashFlowEl = document.getElementById('res_cashflow');
if (monthlyCashFlow >= 0) {
cashFlowEl.classList.remove('rp-negative');
cashFlowEl.classList.add('rp-highlight');
} else {
cashFlowEl.classList.remove('rp-highlight');
cashFlowEl.classList.add('rp-negative');
}
}
Understanding Rental Property Cash Flow
Calculating cash flow is the single most important step in evaluating a real estate investment. Cash flow is the net amount of money moving in and out of a business or property. In the context of real estate, positive cash flow means your rental income exceeds all your expenses, putting money in your pocket every month.
How to Calculate Cash on Cash Return (CoC)
While cash flow tells you how much money you make monthly, Cash on Cash Return tells you how hard your money is working. It measures the annual return the investor made on the property in relation to the amount of mortgage paid during the same year.
A "good" CoC return varies by market and investor strategy, but many investors aim for 8-12%.
What is the Cap Rate?
The Capitalization Rate (Cap Rate) is a metric used to evaluate the profitability of an investment property independent of financing. It helps compare properties as if they were bought with all cash.
Formula: Cap Rate = Net Operating Income (NOI) / Property Asset Value
Note that NOI includes operating expenses (taxes, insurance, maintenance) but excludes mortgage payments. A higher Cap Rate generally indicates a higher potential return, but may also come with higher risk.
Key Expenses to Watch
Vacancy Rate: Always account for the time your property sits empty. A standard conservative estimate is 5-8%.
Maintenance (CapEx): Setting aside 10% of rent for repairs ensures you aren't surprised when a water heater breaks.
Property Management: Even if you self-manage, it's wise to budget 8-10% in case you hire a manager later.
Use the calculator above to run different scenarios. Adjust the down payment to see how leverage impacts your Cash on Cash return, or tweak the rental income to see the break-even point for your investment.