Calculate your monthly Net Operating Income (NOI) and total cash flow.
Income
Fixed Expenses (Monthly)
Variable Expenses (Estimates)
Total Monthly Income:$0.00
Total Monthly Expenses:$0.00
Net Operating Income (NOI):$0.00
Monthly Cash Flow:$0.00
Annual Cash Flow:$0.00
function calculateRentalCashFlow() {
// Get Input Values
var monthlyRent = parseFloat(document.getElementById('monthlyRent').value) || 0;
var otherIncome = parseFloat(document.getElementById('otherIncome').value) || 0;
var mortgagePayment = parseFloat(document.getElementById('mortgagePayment').value) || 0;
var propertyTax = parseFloat(document.getElementById('propertyTax').value) || 0;
var insurance = parseFloat(document.getElementById('insurance').value) || 0;
var hoa = parseFloat(document.getElementById('hoa').value) || 0;
var vacancyRate = parseFloat(document.getElementById('vacancyRate').value) || 0;
var repairsCapEx = parseFloat(document.getElementById('repairsCapEx').value) || 0;
var managementFee = parseFloat(document.getElementById('managementFee').value) || 0;
// Calculate Gross Income
var grossIncome = monthlyRent + otherIncome;
// Calculate Variable Expense Amounts
var vacancyCost = monthlyRent * (vacancyRate / 100);
var repairsCost = monthlyRent * (repairsCapEx / 100);
var managementCost = monthlyRent * (managementFee / 100);
// Calculate Total Expenses
// Note: For Cash Flow, we include Mortgage. For NOI, we exclude Mortgage interest/principal usually,
// but simple calculators often group operating expenses separate from debt service.
var operatingExpenses = propertyTax + insurance + hoa + vacancyCost + repairsCost + managementCost;
var totalExpenses = operatingExpenses + mortgagePayment;
// Calculate Metrics
var noi = grossIncome – operatingExpenses; // Net Operating Income
var monthlyCashFlow = grossIncome – totalExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// Display Results
document.getElementById('resTotalIncome').innerText = '$' + grossIncome.toFixed(2);
document.getElementById('resTotalExpenses').innerText = '$' + totalExpenses.toFixed(2);
document.getElementById('resNOI').innerText = '$' + noi.toFixed(2);
var flowEl = document.getElementById('resCashFlow');
flowEl.innerText = '$' + monthlyCashFlow.toFixed(2);
// Style based on positive/negative
if (monthlyCashFlow >= 0) {
flowEl.className = 'positive-flow';
} else {
flowEl.className = 'negative-flow';
}
document.getElementById('resAnnualFlow').innerText = '$' + annualCashFlow.toFixed(2);
// Show Results Box
document.getElementById('results').style.display = 'block';
}
Understanding Rental Property Cash Flow
Cash flow is the lifeblood of any rental real estate investment. It represents the net amount of cash moving in or out of your investment each month. A positive cash flow means the property generates more income than it costs to operate, putting money directly into your pocket. A negative cash flow implies you must contribute personal funds each month to keep the asset afloat.
Formula:
Cash Flow = (Gross Rental Income + Other Income) – (Operating Expenses + Debt Service)
Key Inputs Explained
Gross Rental Income: The total amount of rent collected from tenants. Ensure you check local market rates (comps) to input a realistic figure.
Vacancy Rate: No property is occupied 100% of the time. A standard conservative estimate is 5% to 8% (roughly 2-4 weeks of vacancy per year). This accounts for turnover periods between tenants.
Operating Expenses: These are costs required to maintain the property, excluding the mortgage. They include taxes, insurance, HOA fees, repairs, landscaping, and property management.
CapEx (Capital Expenditures): Unlike routine repairs (like fixing a leaky faucet), CapEx refers to major replacements like a new roof or HVAC system. Smart investors set aside a percentage of rent (often 5-10%) monthly to save for these future costs.
Net Operating Income (NOI) vs. Cash Flow
Many new investors confuse NOI with Cash Flow. NOI is the profitability of the property before the mortgage is paid. It is used to calculate the Cap Rate. Cash Flow is what is left after the mortgage (principal and interest) is paid. You can have a positive NOI but a negative Cash Flow if your leverage (mortgage) is too high.
What is a "Good" Cash Flow?
While "good" is subjective, many investors aim for $100 to $200 per door per month in pure profit after all expenses and reserves. In high-cost-of-living areas, cash flow might be lower, but appreciation potential is higher. In contrast, lower-cost markets often yield higher monthly cash flow but slower property value appreciation.
Using the 50% Rule for Quick Analysis
If you don't have exact expense numbers, you can use the "50% Rule" for a quick estimate. This rule suggests that 50% of your gross rent will go toward operating expenses (taxes, insurance, repairs, vacancy, management), not including the mortgage. If your mortgage payment is greater than the remaining 50% of the rent, the property likely won't cash flow.