.rp-calculator-wrapper {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
padding: 20px;
background: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
}
.rp-calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 768px) {
.rp-calc-grid {
grid-template-columns: 1fr;
}
}
.rp-input-group {
margin-bottom: 15px;
}
.rp-input-group label {
display: block;
font-weight: 600;
margin-bottom: 5px;
color: #333;
font-size: 14px;
}
.rp-input-group input, .rp-input-group select {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.rp-section-title {
grid-column: 1 / -1;
font-size: 18px;
color: #2c3e50;
margin-bottom: 10px;
border-bottom: 2px solid #3498db;
padding-bottom: 5px;
margin-top: 10px;
}
.rp-btn {
grid-column: 1 / -1;
background-color: #27ae60;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 5px;
cursor: pointer;
transition: background 0.3s;
margin-top: 10px;
}
.rp-btn:hover {
background-color: #219150;
}
.rp-results {
grid-column: 1 / -1;
background: #fff;
border: 1px solid #ddd;
border-radius: 5px;
padding: 20px;
margin-top: 20px;
display: none;
}
.rp-result-row {
display: flex;
justify-content: space-between;
padding: 10px 0;
border-bottom: 1px solid #eee;
}
.rp-result-row:last-child {
border-bottom: none;
}
.rp-big-metric {
text-align: center;
margin-bottom: 20px;
padding: 15px;
background: #f0fdf4;
border: 1px solid #bbf7d0;
border-radius: 6px;
}
.rp-big-metric h3 {
margin: 0 0 10px 0;
color: #166534;
font-size: 24px;
}
.rp-big-metric span {
font-size: 32px;
font-weight: 800;
color: #15803d;
}
.rp-article {
max-width: 800px;
margin: 40px auto 0 auto;
line-height: 1.6;
color: #333;
}
.rp-article h2 {
color: #2c3e50;
margin-top: 30px;
}
.rp-article h3 {
color: #34495e;
}
.rp-article ul {
margin-left: 20px;
}
.rp-error {
color: red;
grid-column: 1 / -1;
display: none;
text-align: center;
margin-top: 10px;
}
function calculateRental() {
// Retrieve inputs
var price = parseFloat(document.getElementById('rp_price').value);
var downPercent = parseFloat(document.getElementById('rp_down_percent').value);
var closingCosts = parseFloat(document.getElementById('rp_closing_costs').value);
var interestRate = parseFloat(document.getElementById('rp_interest').value);
var termYears = parseFloat(document.getElementById('rp_term').value);
var monthlyRent = parseFloat(document.getElementById('rp_rent').value);
var vacancyRate = parseFloat(document.getElementById('rp_vacancy').value);
var annualTax = parseFloat(document.getElementById('rp_tax').value);
var annualInsurance = parseFloat(document.getElementById('rp_insurance').value);
var monthlyHOA = parseFloat(document.getElementById('rp_hoa').value);
var maintPercent = parseFloat(document.getElementById('rp_maintenance').value);
var mgmtPercent = parseFloat(document.getElementById('rp_mgmt').value);
// Validation
if (isNaN(price) || isNaN(downPercent) || isNaN(interestRate) || isNaN(monthlyRent)) {
document.getElementById('rp_error').style.display = 'block';
document.getElementById('rp_results').style.display = 'none';
return;
}
document.getElementById('rp_error').style.display = 'none';
// 1. Loan Calculation
var downPayment = price * (downPercent / 100);
var loanAmount = price – downPayment;
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = termYears * 12;
var mortgagePayment = 0;
if (interestRate === 0) {
mortgagePayment = loanAmount / numberOfPayments;
} else {
mortgagePayment = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
// 2. Income Calculation
var vacancyCost = monthlyRent * (vacancyRate / 100);
var effectiveGrossIncome = monthlyRent – vacancyCost;
// 3. Operating Expenses Calculation (Monthly)
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
var maintenanceCost = monthlyRent * (maintPercent / 100);
var mgmtCost = monthlyRent * (mgmtPercent / 100);
var totalOperatingExpenses = monthlyTax + monthlyInsurance + monthlyHOA + maintenanceCost + mgmtCost;
// 4. Net Operating Income (NOI)
var noi = effectiveGrossIncome – totalOperatingExpenses;
// 5. Cash Flow
var monthlyCashFlow = noi – mortgagePayment;
var annualCashFlow = monthlyCashFlow * 12;
// 6. Returns
var totalCashInvested = downPayment + closingCosts;
var cashOnCash = (annualCashFlow / totalCashInvested) * 100;
var annualNOI = noi * 12;
var capRate = (annualNOI / price) * 100;
// Display Results
document.getElementById('res_cashflow').innerText = "$" + monthlyCashFlow.toFixed(2);
document.getElementById('res_noi').innerText = "$" + noi.toFixed(2);
document.getElementById('res_expenses').innerText = "$" + (totalOperatingExpenses + mortgagePayment).toFixed(2);
document.getElementById('res_mortgage').innerText = "$" + mortgagePayment.toFixed(2);
document.getElementById('res_coc').innerText = cashOnCash.toFixed(2) + "%";
document.getElementById('res_cap').innerText = capRate.toFixed(2) + "%";
// Style Logic for Cashflow
var cfElement = document.getElementById('res_cashflow');
var metricBox = document.querySelector('.rp-big-metric');
if (monthlyCashFlow >= 0) {
cfElement.style.color = "#15803d";
metricBox.style.background = "#f0fdf4";
metricBox.style.borderColor = "#bbf7d0";
} else {
cfElement.style.color = "#b91c1c";
metricBox.style.background = "#fef2f2";
metricBox.style.borderColor = "#fecaca";
}
document.getElementById('rp_results').style.display = 'block';
}
Understanding Rental Property Cash Flow
Investing in real estate is one of the most reliable ways to build long-term wealth, but not every property is a good deal. The difference between a profitable asset and a money pit often comes down to one metric: Cash Flow. This calculator helps investors break down the income and expenses associated with a rental property to determine its viability.
What is Positive Cash Flow?
Positive cash flow occurs when a property's gross income exceeds all of its expenses, including the mortgage, taxes, insurance, and maintenance reserves. For example, if you collect $2,000 in rent and your total outflows are $1,500, your positive cash flow is $500 per month. This surplus can be reinvested, saved for future repairs, or used as passive income.
Key Metrics Explained
This calculator provides several critical metrics that seasoned investors use to evaluate deals:
- NOI (Net Operating Income): This is your total income minus operating expenses. Crucially, NOI excludes mortgage payments. It represents the profitability of the property itself, regardless of how it is financed.
- Cap Rate (Capitalization Rate): Calculated as
(Annual NOI / Purchase Price) × 100. The Cap Rate measures the natural rate of return on the property assuming you paid in all cash. It allows you to compare properties of different sizes and prices effectively.
- Cash-on-Cash Return: This is often the most important metric for investors using leverage (loans). It calculates the return on the actual cash you invested (down payment + closing costs). A Cash-on-Cash return of 8-12% is generally considered a solid target for rental properties.
The 50% Rule and Vacancy
When estimating expenses, many beginners make the mistake of only counting the mortgage, tax, and insurance. However, unexpected costs always arise. The "50% Rule" is a quick rule of thumb suggesting that 50% of your rental income will go toward operating expenses (excluding the mortgage).
Additionally, always factor in Vacancy. No property is occupied 100% of the time. Setting aside 5% to 8% of the monthly rent for vacancy ensures you aren't caught off guard during tenant turnover.
How to Improve Cash Flow
If the results from the calculator show negative or low cash flow, consider these strategies:
- Increase Rent: Are you charging market rates? Slight renovations can justify higher premiums.
- Decrease Expenses: Shop around for cheaper insurance or appeal your property tax assessment.
- Higher Down Payment: Putting more money down reduces your monthly mortgage payment, instantly boosting cash flow (though it may lower your Cash-on-Cash return).
Use this tool to analyze multiple scenarios before making an offer. By adjusting the purchase price or interest rate fields, you can determine the maximum price you should pay to achieve your financial goals.