Analyze the profitability of your real estate investment.
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Monthly Mortgage (P&I):$0.00
Total Monthly Expenses:$0.00
Net Operating Income (Monthly):$0.00
Monthly Cash Flow:$0.00
Cash on Cash ROI:0.00%
Cap Rate:0.00%
function calculateCashFlow() {
// 1. Get input values
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPercent = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var term = parseFloat(document.getElementById('loanTerm').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var taxRate = parseFloat(document.getElementById('propertyTax').value);
var annualIns = parseFloat(document.getElementById('insuranceCost').value);
var hoa = parseFloat(document.getElementById('hoaCost').value);
var vacancyPct = parseFloat(document.getElementById('vacancyRate').value);
var maintPct = parseFloat(document.getElementById('maintenanceRate').value);
// Validation
if (isNaN(price) || isNaN(rent) || isNaN(term)) {
alert("Please enter valid numbers for Price, Rent, and Loan Term.");
return;
}
// 2. Loan Calculations
var downAmount = price * (downPercent / 100);
var loanAmount = price – downAmount;
var monthlyRate = (rate / 100) / 12;
var totalPayments = term * 12;
var mortgagePayment = 0;
if (rate > 0) {
mortgagePayment = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalPayments)) / (Math.pow(1 + monthlyRate, totalPayments) – 1);
} else {
mortgagePayment = loanAmount / totalPayments;
}
// 3. Expense Calculations
var monthlyTax = (price * (taxRate / 100)) / 12;
var monthlyIns = annualIns / 12;
var monthlyVacancy = rent * (vacancyPct / 100);
var monthlyMaint = rent * (maintPct / 100);
// Operating Expenses (excluding mortgage) for NOI
var operatingExpenses = monthlyTax + monthlyIns + hoa + monthlyVacancy + monthlyMaint;
// Total Expenses for Cash Flow
var totalExpenses = operatingExpenses + mortgagePayment;
// 4. Metrics
var monthlyCashFlow = rent – totalExpenses;
var annualCashFlow = monthlyCashFlow * 12;
var monthlyNOI = rent – operatingExpenses;
var annualNOI = monthlyNOI * 12;
// Estimate closing costs as 3% of price for realistic Total Cash Invested
var closingCosts = price * 0.03;
var totalCashInvested = downAmount + closingCosts;
// Just to be safe if 100% financing
if(totalCashInvested <= 0) totalCashInvested = 1;
var cocROI = (annualCashFlow / totalCashInvested) * 100;
var capRate = (annualNOI / price) * 100;
// 5. Update DOM
document.getElementById('resMortgage').innerText = "$" + mortgagePayment.toFixed(2);
document.getElementById('resExpenses').innerText = "$" + totalExpenses.toFixed(2);
document.getElementById('resNOI').innerText = "$" + monthlyNOI.toFixed(2);
var cfElement = document.getElementById('resCashFlow');
cfElement.innerText = "$" + monthlyCashFlow.toFixed(2);
if(monthlyCashFlow < 0) {
cfElement.classList.add('rp-negative');
cfElement.classList.remove('rp-highlight');
} else {
cfElement.classList.remove('rp-negative');
cfElement.classList.add('rp-highlight');
}
document.getElementById('resCoC').innerText = cocROI.toFixed(2) + "%";
document.getElementById('resCapRate').innerText = capRate.toFixed(2) + "%";
document.getElementById('rpResults').style.display = 'block';
}
Understanding Rental Property Cash Flow
Investing in real estate is a powerful way to build wealth, but simply buying a property and renting it out doesn't guarantee a profit. The most critical metric for any buy-and-hold investor is Cash Flow. This calculator helps you determine if a potential investment will put money in your pocket every month or become a financial liability.
How Is Cash Flow Calculated?
Cash flow is the net income remaining after all operating expenses and debt service payments have been deducted from the gross rental income. The formula used in this calculator is:
Gross Income: Monthly Rent.
Less Operating Expenses: Property taxes, insurance, HOA fees, vacancy reserves, and maintenance costs.
Less Debt Service: Principal and interest payments on your mortgage.
Equals: Monthly Cash Flow.
Key Metrics Defined
Beyond simple cash flow, professional investors look at two efficiency ratios to judge a deal:
1. Cash on Cash ROI (Return on Investment)
This measures the annual return on the actual cash you invested (Down Payment + Closing Costs). Unlike a simple return based on property value, this metric accounts for leverage. A good Cash on Cash ROI typically ranges from 8% to 12% or higher, depending on the market.
2. Cap Rate (Capitalization Rate)
The Cap Rate measures the property's natural rate of return assuming you bought it with all cash (no mortgage). It is calculated by dividing the Net Operating Income (NOI) by the purchase price. This helps compare properties side-by-side regardless of how they are financed.
Tips for Improving Cash Flow
If your calculation shows negative or low cash flow, consider these adjustments:
Increase Down Payment: Putting more money down reduces your monthly mortgage payment, instantly boosting cash flow (though it may lower your Cash on Cash ROI).
Raise Rents: Check local comparables to ensure you aren't undercharging. Small cosmetic upgrades can often justify higher rent.
Reduce Operating Costs: Shop around for cheaper insurance or self-manage the property to save on management fees if applicable.
Use this calculator to run different scenarios before making an offer to ensure your real estate investment meets your financial goals.