Analyze the profitability of your real estate investment.
Purchase Details
Income & Expenses
Reserves (Estimates)
Monthly Mortgage (P&I):$0.00
Total Monthly Expenses:$0.00
Net Operating Income (Monthly):$0.00
Monthly Cash Flow:$0.00
Annual Cash Flow:$0.00
Cash on Cash Return (CoC):0.00%
Cap Rate:0.00%
function calculateRental() {
// 1. Get Inputs
var price = parseFloat(document.getElementById('rp_price').value) || 0;
var downPercent = parseFloat(document.getElementById('rp_down').value) || 0;
var interestRate = parseFloat(document.getElementById('rp_rate').value) || 0;
var years = parseFloat(document.getElementById('rp_term').value) || 0;
var rent = parseFloat(document.getElementById('rp_rent').value) || 0;
var annualTax = parseFloat(document.getElementById('rp_tax').value) || 0;
var annualIns = parseFloat(document.getElementById('rp_ins').value) || 0;
var monthlyHoa = parseFloat(document.getElementById('rp_hoa').value) || 0;
var vacPercent = parseFloat(document.getElementById('rp_vac').value) || 0;
var maintPercent = parseFloat(document.getElementById('rp_maint').value) || 0;
var capexPercent = parseFloat(document.getElementById('rp_capex').value) || 0;
var pmPercent = parseFloat(document.getElementById('rp_pm').value) || 0;
// 2. Calculate Mortgage (P&I)
var downPayment = price * (downPercent / 100);
var loanAmount = price – downPayment;
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = years * 12;
var monthlyMortgage = 0;
if (interestRate > 0 && years > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
} else if (years > 0) {
monthlyMortgage = loanAmount / numberOfPayments;
}
// 3. Calculate Monthly Operating Expenses
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
// Variable costs based on rent
var vacancyCost = rent * (vacPercent / 100);
var maintCost = rent * (maintPercent / 100);
var capexCost = rent * (capexPercent / 100);
var pmCost = rent * (pmPercent / 100);
var totalOperatingExpenses = monthlyTax + monthlyIns + monthlyHoa + vacancyCost + maintCost + capexCost + pmCost;
var totalExpensesWithMortgage = totalOperatingExpenses + monthlyMortgage;
// 4. Calculate Metrics
var monthlyNOI = rent – totalOperatingExpenses;
var monthlyCashFlow = rent – totalExpensesWithMortgage;
var annualCashFlow = monthlyCashFlow * 12;
var annualNOI = monthlyNOI * 12;
// Cash on Cash Return = Annual Cash Flow / Total Cash Invested
// Assuming Total Cash Invested = Down Payment for simplicity (ignoring closing costs/rehab for this basic calc)
var cashOnCash = 0;
if (downPayment > 0) {
cashOnCash = (annualCashFlow / downPayment) * 100;
}
// Cap Rate = Annual NOI / Purchase Price
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
// 5. Display Results
var formatCurrency = function(num) {
return '$' + num.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
};
var formatPercent = function(num) {
return num.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2}) + '%';
};
document.getElementById('res_mortgage').innerText = formatCurrency(monthlyMortgage);
document.getElementById('res_expenses').innerText = formatCurrency(totalExpensesWithMortgage);
document.getElementById('res_noi').innerText = formatCurrency(monthlyNOI);
var cfMoEl = document.getElementById('res_cashflow_mo');
cfMoEl.innerText = formatCurrency(monthlyCashFlow);
cfMoEl.className = 'rp-result-value ' + (monthlyCashFlow >= 0 ? 'rp-positive' : 'rp-negative');
var cfYrEl = document.getElementById('res_cashflow_yr');
cfYrEl.innerText = formatCurrency(annualCashFlow);
cfYrEl.className = 'rp-result-value ' + (annualCashFlow >= 0 ? 'rp-positive' : 'rp-negative');
document.getElementById('res_coc').innerText = formatPercent(cashOnCash);
document.getElementById('res_cap').innerText = formatPercent(capRate);
document.getElementById('rp_results').style.display = 'block';
}
Mastering the Rental Property Cash Flow Calculator
Success in real estate investing hinges on the numbers. Unlike emotional purchases, an investment property is a business, and its viability is determined by its ability to generate positive cash flow. This Rental Property Cash Flow Calculator is designed to help investors make data-driven decisions by analyzing potential deals with precision.
Why Cash Flow Analysis is Critical
Cash flow is the profit remaining after all expenses have been paid. Positive cash flow acts as a buffer against market fluctuations and provides passive income. Negative cash flow, often referred to as an "alligator," eats away at your capital each month. A thorough analysis ensures you aren't just buying a property, but buying an income stream.
Understanding Key Metrics
Net Operating Income (NOI): This is your total income minus operating expenses, excluding the mortgage payment. It measures the profitability of the property itself, regardless of financing.
Cash on Cash Return (CoC): Perhaps the most important metric for investors using leverage. It measures the annual return on the actual cash you invested (down payment). For example, if you invest $50,000 and get $5,000 in annual cash flow, your CoC is 10%.
Cap Rate (Capitalization Rate): Calculated as Annual NOI divided by Purchase Price. It represents the potential return if you bought the property all cash. It helps compare properties across different markets.
Hidden Expenses New Investors Miss
Many novice investors calculate profitability by simply subtracting the mortgage from the rent. This is a dangerous oversimplification. To get an accurate picture, you must account for:
Vacancy: Properties will not be rented 100% of the time. Setting aside 5-10% of rent for vacancy is a prudent industry standard.
Maintenance & Repairs: Leaky faucets and broken windows are inevitable. Allocate 5-10% of monthly rent to handle these ongoing costs.
CapEx (Capital Expenditures): Big-ticket items like roofs, HVAC systems, and water heaters eventually need replacing. Budgeting for these monthly prevents a massive financial shock later.
Property Management: Even if you plan to self-manage, it is wise to factor in a management fee (typically 8-10%) to ensure the deal still works if you decide to hire a professional later.
How to Interpret Your Results
If the Monthly Cash Flow is positive, the property pays for itself and puts money in your pocket. A general rule of thumb for many investors is to look for at least $100-$200 per door in net monthly cash flow. If the number is negative, re-evaluate your offer price, financing terms, or the rental market rates before proceeding.