Rental Property Cash Flow Calculator
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Monthly Financials
Gross Income (w/ Vacancy)
$0.00
Principal & Interest
$0.00
Total Operating Expenses
$0.00
Monthly Cash Flow
$0.00
Annual Returns
Net Operating Income (NOI)
$0.00
Cash on Cash Return
0.00%
Cap Rate
0.00%
Understanding Rental Property Cash Flow
Cash flow is the lifeblood of any rental property investment. It represents the net amount of money moving into or out of your business after all expenses have been paid. A positive cash flow means your property is generating profit, while a negative cash flow implies you are losing money every month to hold the asset.
Our Rental Property Cash Flow Calculator helps real estate investors perform a quick but comprehensive analysis of a potential deal. By inputting the purchase price, financing details, and operating expenses, you can determine if a property meets your investment criteria.
Key Metrics Explained
- Monthly Cash Flow: The profit remaining after mortgage, taxes, insurance, and maintenance. Calculated as Income – Expenses – Debt Service.
- Cash on Cash (CoC) Return: This metric measures the annual return on the actual cash invested (down payment + closing costs). It gives you a clear picture of how hard your money is working. Ideally, investors look for CoC returns between 8% and 12%.
- Net Operating Income (NOI): The annual income generated by the property after deducting all operating expenses but before deducting mortgage payments. This is crucial for calculating the Cap Rate.
- Cap Rate: The ratio of NOI to property asset value. It helps compare the profitability of different properties regardless of how they are financed.
How to Estimate Expenses Accurately
One of the biggest mistakes new investors make is underestimating expenses. When using the calculator, ensure you account for:
- Vacancy: Even in hot markets, tenants move out. A standard conservative estimate is 5-8% (approx. 2-3 weeks per year).
- Maintenance: Roofs leak and toilets break. Setting aside 5-10% of monthly rent for repairs is a prudent strategy.
- Capital Expenditures (CapEx): These are big-ticket items like HVAC replacement. While not always a monthly cost, saving for them monthly prevents cash flow shock later.
Why Use a Cash Flow Calculator?
Emotional investing is a recipe for disaster. By relying on hard numbers and specific metrics like CoC and ROI, you remove emotion from the equation. Use this tool to screen multiple properties, adjust your offer price to meet your return goals, or decide if a property is better suited for a flip rather than a hold.
function calculateROI() {
// Get Inputs
var price = parseFloat(document.getElementById('purchasePrice').value) || 0;
var rent = parseFloat(document.getElementById('monthlyRent').value) || 0;
var vacancyPct = parseFloat(document.getElementById('vacancyRate').value) || 0;
var downPaymentPct = parseFloat(document.getElementById('downPayment').value) || 0;
var interestRate = parseFloat(document.getElementById('interestRate').value) || 0;
var years = parseFloat(document.getElementById('loanTerm').value) || 0;
var closingCosts = parseFloat(document.getElementById('closingCosts').value) || 0;
var annualTax = parseFloat(document.getElementById('annualTax').value) || 0;
var annualIns = parseFloat(document.getElementById('annualInsurance').value) || 0;
var monthlyHOA = parseFloat(document.getElementById('monthlyHOA').value) || 0;
var maintPct = parseFloat(document.getElementById('maintRate').value) || 0;
// Calculations
// 1. Initial Investment
var downPaymentAmt = price * (downPaymentPct / 100);
var loanAmount = price – downPaymentAmt;
var totalCashInvested = downPaymentAmt + closingCosts;
// 2. Mortgage Payment (Principal & Interest)
var monthlyRate = (interestRate / 100) / 12;
var numPayments = years * 12;
var monthlyMortgage = 0;
if (monthlyRate > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
} else {
monthlyMortgage = loanAmount / numPayments;
}
// 3. Operating Income
var vacancyLoss = rent * (vacancyPct / 100);
var effectiveGrossIncome = rent – vacancyLoss;
// 4. Operating Expenses
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
var maintCost = rent * (maintPct / 100);
var totalOperatingExpenses = monthlyTax + monthlyIns + monthlyHOA + maintCost;
// 5. Cash Flow
var monthlyCashFlow = effectiveGrossIncome – totalOperatingExpenses – monthlyMortgage;
var annualCashFlow = monthlyCashFlow * 12;
// 6. Returns
var noi = (effectiveGrossIncome – totalOperatingExpenses) * 12;
var cocReturn = 0;
if (totalCashInvested > 0) {
cocReturn = (annualCashFlow / totalCashInvested) * 100;
}
var capRate = 0;
if (price > 0) {
capRate = (noi / price) * 100;
}
// Formatting Helper
var formatCurrency = function(num) {
return '$' + num.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
};
var formatPercent = function(num) {
return num.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}) + '%';
};
// Update DOM
document.getElementById('resIncome').innerText = formatCurrency(effectiveGrossIncome);
document.getElementById('resMortgage').innerText = formatCurrency(monthlyMortgage);
document.getElementById('resExpenses').innerText = formatCurrency(totalOperatingExpenses); // Just OpEx, mortgage is separate
var cashFlowEl = document.getElementById('resCashFlow');
cashFlowEl.innerText = formatCurrency(monthlyCashFlow);
if(monthlyCashFlow >= 0) {
cashFlowEl.className = "highlight-value positive";
} else {
cashFlowEl.className = "highlight-value negative";
}
document.getElementById('resNOI').innerText = formatCurrency(noi);
var cocEl = document.getElementById('resCoC');
cocEl.innerText = formatPercent(cocReturn);
if(cocReturn >= 0) cocEl.className = "result-value positive";
else cocEl.className = "result-value negative";
document.getElementById('resCapRate').innerText = formatPercent(capRate);
}
// Initialize on load
window.onload = calculateROI;