Rental Property Cash Flow Calculator
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Rental Property Cash Flow Calculator
Analysis Results
Monthly Mortgage Payment (P&I):
$0.00
Total Monthly Expenses (inc. Mortgage):
$0.00
Monthly Cash Flow:
$0.00
Annual Cash Flow:
$0.00
Net Operating Income (NOI) / Year:
$0.00
Cap Rate:
0.00%
Cash on Cash Return (CoC):
0.00%
How to Analyze a Rental Property Investment
Investing in real estate is a powerful way to build wealth, but analyzing the numbers correctly is critical to avoiding bad investments. This Rental Property Cash Flow Calculator helps investors determine if a specific property will generate positive income (cash flow) or if it will be a liability.
Understanding the Key Metrics
1. Monthly Cash Flow
This is the money left over after all expenses are paid. A positive cash flow means the property is putting money in your pocket every month. It is calculated as:
- Formula: Total Rental Income – (Mortgage + Taxes + Insurance + HOA + Maintenance/Vacancy Reserves)
2. Net Operating Income (NOI)
NOI is a standard profitability metric that looks at the property's ability to generate revenue, excluding financing costs (the mortgage). It is crucial for calculating the Cap Rate.
- Formula: (Annual Rental Income) – (Annual Operating Expenses excluding Mortgage Principal & Interest)
3. Cap Rate (Capitalization Rate)
The Cap Rate helps you compare the return of a real estate investment independent of how you finance it. It represents the percentage return an investor would receive on an all-cash purchase.
- Formula: (NOI / Purchase Price) × 100%
- Good Target: Generally, a Cap Rate between 4% and 10% is considered standard, depending on the location and risk profile.
4. Cash on Cash Return (CoC)
This is often the most important metric for investors using leverage (loans). It measures the annual return on the actual cash you invested (Down Payment + Closing Costs), rather than the total price of the home.
- Formula: (Annual Cash Flow / Total Cash Invested) × 100%
- Good Target: Many investors aim for a CoC return of 8-12% or higher.
Why Include Maintenance and Vacancy?
A common mistake new landlords make is assuming they will collect rent 12 months a year with zero repairs. In reality:
- Vacancy: Tenants move out. You should budget for at least 5% (roughly 2-3 weeks) of vacancy per year.
- Maintenance: Water heaters break, roofs leak, and paint chips. Setting aside 5-10% of monthly rent creates a safety net for these inevitable costs.
Use the calculator above to adjust these variables and stress-test your investment before you buy.
function calculateCashFlow() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var closingCosts = parseFloat(document.getElementById('closingCosts').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var termYears = parseFloat(document.getElementById('loanTerm').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var tax = parseFloat(document.getElementById('propertyTax').value);
var insurance = parseFloat(document.getElementById('insurance').value);
var hoa = parseFloat(document.getElementById('hoa').value);
var maintPercent = parseFloat(document.getElementById('maintenance').value);
// Validation
if (isNaN(price) || isNaN(downPayment) || isNaN(rent) || isNaN(interestRate) || isNaN(termYears)) {
alert("Please enter valid numbers for all fields.");
return;
}
// 2. Calculate Mortgage (Principal & Interest)
var loanAmount = price – downPayment;
var monthlyRate = (interestRate / 100) / 12;
var numPayments = termYears * 12;
var mortgagePayment = 0;
if (interestRate === 0) {
mortgagePayment = loanAmount / numPayments;
} else {
mortgagePayment = (loanAmount * monthlyRate) / (1 – Math.pow(1 + monthlyRate, -numPayments));
}
// 3. Calculate Expenses
var maintAmount = rent * (maintPercent / 100);
var totalOperatingExpenses = tax + insurance + hoa + maintAmount; // Excluding mortgage
var totalMonthlyExpenses = totalOperatingExpenses + mortgagePayment;
// 4. Calculate Cash Flow
var monthlyCashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// 5. Calculate NOI (Net Operating Income)
var annualNOI = (rent * 12) – (totalOperatingExpenses * 12);
// 6. Calculate Returns
var totalCashInvested = downPayment + closingCosts;
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
var cocReturn = 0;
if (totalCashInvested > 0) {
cocReturn = (annualCashFlow / totalCashInvested) * 100;
}
// 7. Display Results
document.getElementById('results-area').style.display = 'block';
// Format Currency Function
function formatCurrency(num) {
return new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' }).format(num);
}
// Format Percent Function
function formatPercent(num) {
return num.toFixed(2) + '%';
}
document.getElementById('resMortgage').innerText = formatCurrency(mortgagePayment);
document.getElementById('resExpenses').innerText = formatCurrency(totalMonthlyExpenses);
var cfEl = document.getElementById('resMonthlyCashFlow');
cfEl.innerText = formatCurrency(monthlyCashFlow);
cfEl.className = 'result-value ' + (monthlyCashFlow >= 0 ? 'positive' : 'negative');
var acfEl = document.getElementById('resAnnualCashFlow');
acfEl.innerText = formatCurrency(annualCashFlow);
acfEl.className = 'result-value ' + (annualCashFlow >= 0 ? 'positive' : 'negative');
document.getElementById('resNOI').innerText = formatCurrency(annualNOI);
document.getElementById('resCapRate').innerText = formatPercent(capRate);
var cocEl = document.getElementById('resCoC');
cocEl.innerText = formatPercent(cocReturn);
cocEl.className = 'result-value ' + (cocReturn >= 0 ? 'positive' : 'negative');
}