Analyze the potential cash flow and ROI of your real estate investment.
Purchase Information
Income & Expenses
Investment Analysis
Monthly Cash Flow
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Cash on Cash Return
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Monthly Mortgage
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Total Monthly Expenses
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function calculateRental() {
// 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 annualTax = parseFloat(document.getElementById('rp_tax').value);
var annualIns = parseFloat(document.getElementById('rp_ins').value);
var monthlyHOA = parseFloat(document.getElementById('rp_hoa').value);
// Validation
if (isNaN(price) || isNaN(downPercent) || isNaN(rate) || isNaN(term) || isNaN(rent)) {
alert("Please enter valid numbers for all required fields.");
return;
}
// Logic for Loan Calculations
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = (rate / 100) / 12;
var totalPayments = term * 12;
// Mortgage Payment (Principal + Interest)
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyMortgage = 0;
if (rate === 0) {
monthlyMortgage = loanAmount / totalPayments;
} else {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalPayments)) / (Math.pow(1 + monthlyRate, totalPayments) – 1);
}
// Monthly Expenses Calculation
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
var totalMonthlyExpenses = monthlyMortgage + monthlyTax + monthlyIns + monthlyHOA;
// Cash Flow Calculation
var monthlyCashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// Cash on Cash Return Calculation
// Initial investment usually includes down payment + closing costs + repairs.
// For simplicity, we assume closing costs are roughly 3% of price, added to down payment.
var estimatedClosingCosts = price * 0.03;
var totalInitialInvestment = downPaymentAmount + estimatedClosingCosts;
var cocReturn = (annualCashFlow / totalInitialInvestment) * 100;
// Update UI
var cashFlowEl = document.getElementById('res_cash_flow');
cashFlowEl.innerHTML = "$" + monthlyCashFlow.toFixed(2);
if(monthlyCashFlow < 0) {
cashFlowEl.classList.add('negative');
} else {
cashFlowEl.classList.remove('negative');
}
document.getElementById('res_coc').innerHTML = cocReturn.toFixed(2) + "%";
document.getElementById('res_mortgage').innerHTML = "$" + monthlyMortgage.toFixed(2);
document.getElementById('res_expenses').innerHTML = "$" + totalMonthlyExpenses.toFixed(2);
// Show Results container
document.getElementById('rp_results').style.display = 'block';
}
Understanding Rental Property Cash Flow Analysis
Calculating cash flow is the most critical step in evaluating a rental property investment. Positive cash flow means your asset is generating income after all expenses are paid, while negative cash flow implies you are losing money every month to hold the property.
How to Calculate Cash Flow
The formula for rental property cash flow is relatively simple in theory but requires accurate data inputs:
Gross Income: This is primarily your monthly rent, but can also include parking fees, laundry income, or pet fees.
Operating Expenses: These include taxes, insurance, HOA fees, maintenance reserves, and property management fees.
Debt Service: This is your monthly mortgage payment (principal and interest).
While cash flow measures the raw dollars earned, Cash on Cash (CoC) Return measures the efficiency of your investment. It answers the question: "For every dollar I invested, what percentage am I getting back annually?"
Most investors aim for a CoC return between 8% and 12%. However, in high-appreciation markets, investors might accept a lower CoC (4-6%) banking on the property value increasing over time. In contrast, in markets with low appreciation, investors typically demand a higher CoC return to justify the risk.
Common Expenses Investors Forget
When using this calculator, ensure you aren't underestimating expenses. Common oversights include:
Vacancy Rates: Properties won't be rented 365 days a year. It's prudent to budget 5-8% of rent for vacancy.
CapEx (Capital Expenditures): Roofs, HVAC systems, and water heaters eventually break. Setting aside 5-10% of rent for future big-ticket items is essential for long-term profitability.
Using the 1% Rule
A quick rule of thumb used by investors is the 1% Rule. This rule suggests that the monthly rent should be at least 1% of the purchase price. For example, a $300,000 home should rent for $3,000/month. While it is harder to find properties that meet this rule in today's market, it remains a useful benchmark for identifying potential cash flow positive properties.