Analyze your real estate investment potential instantly.
(Taxes, Insurance, HOA, Repairs)
Monthly Mortgage Payment (P&I):$0.00
Monthly Cash Flow:$0.00
Net Operating Income (NOI) / Year:$0.00
Cash on Cash Return (CoC):0.00%
Cap Rate:0.00%
function calculateRentalCashFlow() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('rpc-price').value);
var downPercent = parseFloat(document.getElementById('rpc-down-percent').value);
var rate = parseFloat(document.getElementById('rpc-rate').value);
var term = parseFloat(document.getElementById('rpc-term').value);
var rent = parseFloat(document.getElementById('rpc-rent').value);
var vacancyRate = parseFloat(document.getElementById('rpc-vacancy').value);
var opex = parseFloat(document.getElementById('rpc-opex').value);
var closing = parseFloat(document.getElementById('rpc-closing').value);
// 2. Validation
if (isNaN(price) || isNaN(downPercent) || isNaN(rate) || isNaN(term) || isNaN(rent) || isNaN(vacancyRate) || isNaN(opex) || isNaN(closing)) {
alert("Please enter valid numbers in all fields.");
return;
}
// 3. Core Calculations
// Loan Calculation
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = (rate / 100) / 12;
var totalPayments = term * 12;
var monthlyMortgage = 0;
if (rate === 0) {
monthlyMortgage = loanAmount / totalPayments;
} else {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalPayments)) / (Math.pow(1 + monthlyRate, totalPayments) – 1);
}
// Income Calculations
var monthlyVacancyLoss = rent * (vacancyRate / 100);
var effectiveGrossIncome = rent – monthlyVacancyLoss;
// Cash Flow Calculations
var totalMonthlyExpenses = opex + monthlyMortgage;
var monthlyCashFlow = effectiveGrossIncome – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// ROI Metrics
var annualNOI = (effectiveGrossIncome – opex) * 12;
var totalCashInvested = downPaymentAmount + closing;
var cocReturn = 0;
if (totalCashInvested > 0) {
cocReturn = (annualCashFlow / totalCashInvested) * 100;
}
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
// 4. Update DOM
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
document.getElementById('res-mortgage').innerHTML = formatter.format(monthlyMortgage);
document.getElementById('res-cashflow').innerHTML = formatter.format(monthlyCashFlow);
document.getElementById('res-noi').innerHTML = formatter.format(annualNOI);
document.getElementById('res-coc').innerHTML = cocReturn.toFixed(2) + "%";
document.getElementById('res-cap').innerHTML = capRate.toFixed(2) + "%";
// Show Results
document.getElementById('rpc-results').style.display = 'block';
// Change color based on positive/negative flow
var cashFlowEl = document.getElementById('res-cashflow');
if (monthlyCashFlow >= 0) {
cashFlowEl.style.color = '#27ae60';
} else {
cashFlowEl.style.color = '#c0392b';
}
}
Understanding Your 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. To succeed, you must understand the numbers behind the deal. This Rental Property Cash Flow Calculator helps investors analyze the potential profitability of an income property by accounting for income, expenses, and financing costs.
What is Monthly Cash Flow?
Cash flow is the net amount of cash moving into or out of your investment each month. It is calculated by taking your Gross Rental Income and subtracting all expenses, including operating costs (taxes, insurance, maintenance) and debt service (mortgage payments).
Positive cash flow means the property pays for itself and generates profit. Negative cash flow means you are paying out of pocket every month to keep the property running—a risky position for most investors.
Key Metrics Explained
Net Operating Income (NOI): This represents the annual profitability of the property before financing costs. It is calculated as (Total Income – Operating Expenses). It helps you compare the raw performance of different properties regardless of how they are financed.
Cash on Cash Return (CoC): This is arguably the most important metric for investors. It measures the annual return on the actual cash you invested (Down Payment + Closing Costs). A CoC of 8-12% is often considered a solid benchmark for rental properties.
Cap Rate (Capitalization Rate): This percentage indicates the rate of return on a real estate investment property based on the income that the property is expected to generate. It is calculated as (NOI / Purchase Price). Higher cap rates generally imply higher risk or higher return potential.
How to Improve Your Cash Flow
If your calculation shows a negative or low cash flow, consider the following adjustments:
Increase Rent: Are you charging market rates? Small increases can significantly boost the bottom line.
Reduce Expenses: Shop around for cheaper insurance, challenge property tax assessments, or manage the property yourself to save on management fees.
Larger Down Payment: Putting more money down reduces your loan amount and monthly mortgage payment, instantly increasing monthly cash flow (though it may lower your Cash on Cash return).
Why Use a Rental Property Calculator?
Real estate markets move quickly. Having a reliable tool to instantly calculate mortgage payments, vacancy losses, and ROI metrics allows you to make data-driven decisions rather than emotional ones. Whether you are analyzing a single-family home, a duplex, or a condo, accurate math is the foundation of successful real estate investing.