Determine the monthly profitability of your real estate investment.
Income
Fixed Expenses
Variable Expenses
Gross Potential Income:$0.00
– Vacancy Loss:$0.00
= Effective Gross Income:$0.00
Total Fixed Expenses:$0.00
Total Variable Expenses:$0.00
Monthly Cash Flow:$0.00
Annual Cash Flow:$0.00
What is Rental Property Cash Flow?
Rental property cash flow is the net amount of money left over from your rental property's income after all operating expenses and debt service (mortgage) have been paid. It is the single most important metric for buy-and-hold real estate investors because it determines whether the asset is a liability (costing you money every month) or an asset (putting money in your pocket).
Understanding cash flow allows investors to evaluate the performance of a property, plan for future repairs, and scale their portfolios sustainably. A positive cash flow provides a safety margin against vacancies and unexpected repairs.
How to Use This Calculator
This tool is designed to provide a comprehensive analysis of a rental property's monthly performance. Here is a breakdown of the required inputs:
Monthly Rent & Other Income: The total gross revenue the property generates. Don't forget laundry, parking, or storage fees.
Vacancy Rate: No property is occupied 100% of the time. A standard conservative estimate is 5% to 8% (roughly 2-3 weeks per year).
Fixed Expenses: Recurring costs that do not change significantly month-to-month, such as your mortgage, taxes, insurance, and HOA fees.
Variable Expenses: These are estimated percentages set aside for future costs. Allocating 5-10% for repairs and another 5-10% for Capital Expenditures (CapEx like a new roof or HVAC) is industry standard.
Interpreting Your Results
Once you calculate your numbers, you will see your Monthly Cash Flow. Here is how to interpret the data:
Positive Cash Flow: The property pays for itself and generates profit. This is the goal for most investors. A common benchmark is $100-$200 per door per month for single-family homes.
Negative Cash Flow: The property costs more to operate than it brings in. This might be acceptable in high-appreciation markets, but it increases risk significantly.
Effective Gross Income: This is your real income after accounting for vacancy. Lenders often use this figure rather than gross rent when qualifying you for loans.
Strategies to Increase Cash Flow
If your calculation shows a negative or low cash flow, consider these strategies:
Increase Rent: ensure you are charging market rates by comparing with local listings.
Decrease Expenses: Shop around for cheaper insurance, appeal property tax assessments, or manage the property yourself to save the management fee.
Value-Add Improvements: minor renovations (LVP flooring, fresh paint) can often justify a significant rent increase.
function calculateRentalCashFlow() {
// 1. Get Income Inputs
var rent = parseFloat(document.getElementById('monthlyRent').value);
var otherInc = parseFloat(document.getElementById('otherIncome').value);
var vacancyRate = parseFloat(document.getElementById('vacancyRate').value);
// 2. Get Fixed Expense Inputs
var mortgage = parseFloat(document.getElementById('mortgagePayment').value);
var tax = parseFloat(document.getElementById('propertyTax').value);
var insurance = parseFloat(document.getElementById('insurance').value);
var hoa = parseFloat(document.getElementById('hoaFee').value);
// 3. Get Variable Expense Percentages
var repairRate = parseFloat(document.getElementById('repairRate').value);
var capexRate = parseFloat(document.getElementById('capexRate').value);
var mgmtRate = parseFloat(document.getElementById('mgmtRate').value);
// Validate Inputs (Handle NaN by defaulting to 0)
if (isNaN(rent)) rent = 0;
if (isNaN(otherInc)) otherInc = 0;
if (isNaN(vacancyRate)) vacancyRate = 0;
if (isNaN(mortgage)) mortgage = 0;
if (isNaN(tax)) tax = 0;
if (isNaN(insurance)) insurance = 0;
if (isNaN(hoa)) hoa = 0;
if (isNaN(repairRate)) repairRate = 0;
if (isNaN(capexRate)) capexRate = 0;
if (isNaN(mgmtRate)) mgmtRate = 0;
// 4. Calculations
var grossPotentialIncome = rent + otherInc;
// Vacancy is lost income
var vacancyLoss = grossPotentialIncome * (vacancyRate / 100);
// Effective Gross Income (Money actually collected)
var effectiveIncome = grossPotentialIncome – vacancyLoss;
// Fixed Expenses Total
var totalFixed = mortgage + tax + insurance + hoa;
// Variable Expenses Calculation
// Repairs & CapEx are usually based on Gross Potential Income (standard practice)
// Management is usually based on Effective Income (collected rent)
var repairCost = grossPotentialIncome * (repairRate / 100);
var capexCost = grossPotentialIncome * (capexRate / 100);
var mgmtCost = effectiveIncome * (mgmtRate / 100);
var totalVariable = repairCost + capexCost + mgmtCost;
// Cash Flow
var totalExpenses = totalFixed + totalVariable;
var monthlyCashFlow = effectiveIncome – totalExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// 5. Display Results
// Helper function for formatting currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
});
document.getElementById('resGrossIncome').innerText = formatter.format(grossPotentialIncome);
document.getElementById('resVacancy').innerText = "-" + formatter.format(vacancyLoss);
document.getElementById('resEffectiveIncome').innerText = formatter.format(effectiveIncome);
document.getElementById('resFixedExpenses').innerText = formatter.format(totalFixed);
document.getElementById('resVariableExpenses').innerText = formatter.format(totalVariable);
document.getElementById('resCashFlow').innerText = formatter.format(monthlyCashFlow);
document.getElementById('resAnnualCashFlow').innerText = formatter.format(annualCashFlow);
// Styling for positive/negative cash flow
var cashFlowElement = document.getElementById('resCashFlow');
if (monthlyCashFlow >= 0) {
cashFlowElement.style.color = "#27ae60"; // Green
} else {
cashFlowElement.style.color = "#c0392b"; // Red
}
// Show result section
document.getElementById('rpResults').style.display = 'block';
}