Analyze the profitability of your real estate investment.
Income (Monthly)
Fixed Expenses (Monthly)
Variable Expenses (%)
Gross Monthly Income:$0.00
Operating Expenses (excl. Mortgage):$0.00
Net Operating Income (NOI):$0.00
Mortgage Debt Service:$0.00
Monthly Cash Flow:$0.00
Annual Cash Flow:$0.00
function calculateRentalCashFlow() {
// 1. Get Inputs
var grossRent = parseFloat(document.getElementById('grossRent').value) || 0;
var otherIncome = parseFloat(document.getElementById('otherIncome').value) || 0;
var mortgage = parseFloat(document.getElementById('mortgagePayment').value) || 0;
var tax = parseFloat(document.getElementById('propertyTax').value) || 0;
var insurance = parseFloat(document.getElementById('insurance').value) || 0;
var hoa = parseFloat(document.getElementById('hoaFees').value) || 0;
var vacancyRate = parseFloat(document.getElementById('vacancyRate').value) || 0;
var repairRate = parseFloat(document.getElementById('repairRate').value) || 0;
var capexRate = parseFloat(document.getElementById('capexRate').value) || 0;
var managementRate = parseFloat(document.getElementById('managementRate').value) || 0;
// 2. Calculate Gross Potential Income
var totalPotentialIncome = grossRent + otherIncome;
// 3. Calculate Variable Cost Amounts (Based on Gross Rent usually, but sometimes Gross Income. We use Gross Rent for conservative estimates)
var vacancyCost = grossRent * (vacancyRate / 100);
var repairCost = grossRent * (repairRate / 100);
var capexCost = grossRent * (capexRate / 100);
var managementCost = grossRent * (managementRate / 100);
// 4. Effective Gross Income (Potential – Vacancy)
var effectiveGrossIncome = totalPotentialIncome – vacancyCost;
// 5. Total Operating Expenses (OpEx) – Excluding Mortgage
// OpEx includes Taxes, Insurance, HOA, Repairs, CapEx, Management
var totalOpEx = tax + insurance + hoa + repairCost + capexCost + managementCost;
// 6. Net Operating Income (NOI)
var noi = effectiveGrossIncome – totalOpEx;
// 7. Cash Flow
var monthlyCashFlow = noi – mortgage;
var annualCashFlow = monthlyCashFlow * 12;
// 8. Update UI
document.getElementById('results').style.display = 'block';
document.getElementById('resGrossIncome').innerHTML = '$' + totalPotentialIncome.toFixed(2);
document.getElementById('resOpEx').innerHTML = '$' + totalOpEx.toFixed(2);
document.getElementById('resNOI').innerHTML = '$' + noi.toFixed(2);
document.getElementById('resDebt').innerHTML = '$' + mortgage.toFixed(2);
var monthEl = document.getElementById('resMonthlyFlow');
var yearEl = document.getElementById('resAnnualFlow');
monthEl.innerHTML = '$' + monthlyCashFlow.toFixed(2);
yearEl.innerHTML = '$' + annualCashFlow.toFixed(2);
// Styling for positive/negative
if(monthlyCashFlow < 0) {
monthEl.classList.add('negative');
monthEl.style.color = '#c0392b';
yearEl.classList.add('negative');
yearEl.style.color = '#c0392b';
} else {
monthEl.classList.remove('negative');
monthEl.style.color = '#27ae60';
yearEl.classList.remove('negative');
yearEl.style.color = '#27ae60';
}
}
Understanding Rental Property Cash Flow
Investing in real estate is one of the most reliable ways to build wealth, but it relies heavily on the math working in your favor. This Rental Property Cash Flow Calculator helps investors determine if a property is an asset (puts money in your pocket) or a liability (takes money out).
What is Cash Flow?
Cash flow is the net amount of cash moving in and out of a business or investment. In real estate terms, it is the money left over after all operating expenses and debt service (mortgage payments) have been paid from the collected rent.
The formula is simple but strict:
Gross Income – Operating Expenses = Net Operating Income (NOI)
NOI – Debt Service = Cash Flow
Why the "1% Rule" isn't Enough
Many new investors use "rules of thumb" like the 1% rule (monthly rent should be 1% of the purchase price). While useful for screening, these heuristics do not account for specific expenses like HOA fees, high property taxes, or older homes requiring significant CapEx (Capital Expenditures).
Our calculator allows you to input these specific variables to get a true picture of the investment's performance. For example, a property with a cheap mortgage but high vacancy rates and management fees can quickly turn cash flow negative.
Key Input Definitions
Vacancy Rate: Properties are rarely occupied 365 days a year. A standard conservative estimate is 5% to 8% (roughly 2-4 weeks of vacancy per year).
CapEx (Capital Expenditures): This is money set aside for big-ticket items that will eventually break, such as the roof, HVAC, or water heater. Even if they aren't broken now, you should allocate 5-10% of rent to save for them.
Property Management: Even if you plan to self-manage, it is wise to calculate a 10% fee. This ensures the "deal" works even if you eventually hire a manager, and it pays you for your own time.
NOI (Net Operating Income): This is the profitability of the property irrespective of financing. It is crucial for calculating the Cap Rate.
What is a Good Cash Flow?
For many "Buy and Hold" investors, a goal of $100 to $200 per door, per month in pure profit is a common benchmark. However, this depends on your strategy. Some investors accept lower cash flow in high-appreciation markets, while others require high cash flow in markets with lower potential for price growth.
Use this tool to tweak your numbers—try negotiating the purchase price (lowering the mortgage) or raising the rent—to see how it impacts your bottom line.