function calculateCapRate() {
// 1. Get Input Values
var propertyValue = parseFloat(document.getElementById('cp_property_value').value);
var monthlyRent = parseFloat(document.getElementById('cp_monthly_rent').value);
var vacancyRate = parseFloat(document.getElementById('cp_vacancy_rate').value);
var tax = parseFloat(document.getElementById('cp_annual_tax').value);
var insurance = parseFloat(document.getElementById('cp_annual_insurance').value);
var maintenance = parseFloat(document.getElementById('cp_annual_maint').value);
var management = parseFloat(document.getElementById('cp_annual_mgmt').value);
// 2. Validate Inputs (Handle edge cases and NaNs)
if (isNaN(propertyValue) || propertyValue <= 0) {
alert("Please enter a valid Property Value.");
return;
}
if (isNaN(monthlyRent)) monthlyRent = 0;
if (isNaN(vacancyRate)) vacancyRate = 0;
if (isNaN(tax)) tax = 0;
if (isNaN(insurance)) insurance = 0;
if (isNaN(maintenance)) maintenance = 0;
if (isNaN(management)) management = 0;
// 3. Logic: Calculate Annual Gross Income
var grossPotentialIncome = monthlyRent * 12;
// 4. Logic: Calculate Vacancy Loss
var vacancyLoss = grossPotentialIncome * (vacancyRate / 100);
// 5. Logic: Effective Gross Income
var effectiveGrossIncome = grossPotentialIncome – vacancyLoss;
// 6. Logic: Total Operating Expenses
var totalExpenses = tax + insurance + maintenance + management;
// 7. Logic: Net Operating Income (NOI)
var noi = effectiveGrossIncome – totalExpenses;
// 8. Logic: Cap Rate Formula = (NOI / Property Value) * 100
var capRate = (noi / propertyValue) * 100;
// 9. Display Results
document.getElementById('cp_display_income').innerText = "$" + effectiveGrossIncome.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('cp_display_expenses').innerText = "$" + totalExpenses.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('cp_display_noi').innerText = "$" + noi.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('cp_display_rate').innerText = capRate.toFixed(2) + "%";
// Show the result box
document.getElementById('cp_result_box').style.display = "block";
}
How to Calculate Rental Property Cap Rate
The Capitalization Rate, or "Cap Rate," is one of the most fundamental metrics used in real estate investing. It measures the rate of return on a real estate investment property based on the income that the property is expected to generate. Unlike ROI (Return on Investment) or Cash-on-Cash return, the Cap Rate strictly analyzes the property's natural ability to generate profit, independent of how the property was financed.
The Cap Rate Formula
The mathematics behind the Cap Rate are straightforward, but accuracy depends entirely on the quality of the input data. The formula is:
Cap Rate = (Net Operating Income / Current Market Value) × 100
To use this formula effectively, you must understand its two main components: Net Operating Income (NOI) and Market Value.
Understanding Net Operating Income (NOI)
NOI is the annual income generated by an income-producing property after collecting all revenue and paying all operating expenses. It is crucial to note what is excluded from NOI.
Included in NOI: Rental income, parking fees, laundry coin revenue, pet fees.
Deducted from NOI (Operating Expenses): Property management fees, insurance, property taxes, utilities, landscaping, maintenance, repairs, and vacancy losses.
Excluded from NOI: Mortgage payments (principal and interest), capital expenditures (major renovations like a new roof), and income taxes.
Because mortgage payments are excluded, the Cap Rate allows you to compare the profitability of two different properties directly, regardless of whether you pay cash or take out a loan.
Step-by-Step Calculation Example
Let's calculate the Cap Rate for a single-family rental home to illustrate the process:
Step 2: Calculate NOI
$28,500 (Income) – $8,000 (Expenses) = $20,500 NOI
Step 3: Divide by Market Value
$20,500 / $300,000 = 0.0683
Step 4: Convert to Percentage
0.0683 × 100 = 6.83% Cap Rate
What is a Good Cap Rate?
There is no universal "good" Cap Rate, as it depends heavily on the location, asset class, and current economic environment. generally speaking:
4% to 5%: Common in high-demand, low-risk areas (like downtown NYC or San Francisco). Appreciation potential is high, but immediate cash flow is lower.
6% to 8%: Often considered a healthy balance of risk and return for residential properties in stable suburban markets.
8% to 10%+: Found in riskier markets or properties requiring significant work. These offer higher cash flow to compensate for the higher risk.
Investors should use the Cap Rate calculator as a screening tool. If a property meets your Cap Rate threshold, it warrants a deeper "due diligence" analysis. If it falls short, you can move on to the next opportunity quickly.