.rp-calculator-container {
max-width: 800px;
margin: 0 auto;
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
color: #333;
background: #f9f9f9;
padding: 20px;
border-radius: 8px;
box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}
.rp-calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.rp-calc-grid {
grid-template-columns: 1fr;
}
}
.rp-input-group {
margin-bottom: 15px;
}
.rp-input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 0.9em;
}
.rp-input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 1em;
box-sizing: border-box;
}
.rp-input-group input:focus {
border-color: #2c3e50;
outline: none;
}
.rp-section-title {
grid-column: 1 / -1;
font-size: 1.2em;
margin-top: 10px;
margin-bottom: 10px;
color: #2c3e50;
border-bottom: 2px solid #ddd;
padding-bottom: 5px;
}
.rp-btn {
grid-column: 1 / -1;
background-color: #27ae60;
color: white;
border: none;
padding: 15px;
font-size: 1.1em;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background 0.3s;
text-align: center;
width: 100%;
}
.rp-btn:hover {
background-color: #219150;
}
.rp-results {
grid-column: 1 / -1;
background: #fff;
padding: 20px;
border-radius: 4px;
border: 1px solid #eee;
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-result-label {
color: #666;
}
.rp-result-value {
font-weight: bold;
font-size: 1.1em;
}
.rp-highlight {
color: #27ae60;
font-size: 1.3em;
}
.rp-highlight-neg {
color: #c0392b;
font-size: 1.3em;
}
.rp-article {
max-width: 800px;
margin: 40px auto;
font-family: 'Georgia', serif;
line-height: 1.6;
color: #444;
}
.rp-article h2 {
font-family: 'Segoe UI', sans-serif;
color: #2c3e50;
margin-top: 30px;
}
.rp-article p {
margin-bottom: 15px;
}
.rp-article ul {
margin-bottom: 20px;
padding-left: 20px;
}
.rp-article li {
margin-bottom: 10px;
}
function calculateCashFlow() {
// 1. Get Inputs
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPercent = parseFloat(document.getElementById('downPayment').value);
var interest = parseFloat(document.getElementById('interestRate').value);
var termYears = parseFloat(document.getElementById('loanTerm').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var taxYearly = parseFloat(document.getElementById('propertyTax').value);
var insYearly = parseFloat(document.getElementById('insurance').value);
var vacancyPercent = parseFloat(document.getElementById('vacancyRate').value);
var maintPercent = parseFloat(document.getElementById('maintenance').value);
var mgmtPercent = parseFloat(document.getElementById('managementFee').value);
// 2. Validate
if (isNaN(price) || isNaN(rent) || isNaN(interest) || isNaN(termYears)) {
alert("Please enter valid numbers for all fields.");
return;
}
// 3. Loan Calculations
var downAmount = price * (downPercent / 100);
var loanAmount = price – downAmount;
var monthlyRate = (interest / 100) / 12;
var totalPayments = termYears * 12;
// Mortgage P&I Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
var monthlyMortgage = 0;
if (interest === 0) {
monthlyMortgage = loanAmount / totalPayments;
} else {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalPayments)) / (Math.pow(1 + monthlyRate, totalPayments) – 1);
}
// 4. Operating Expenses
var monthlyTax = taxYearly / 12;
var monthlyIns = insYearly / 12;
var vacancyCost = rent * (vacancyPercent / 100);
var maintCost = rent * (maintPercent / 100);
var mgmtCost = rent * (mgmtPercent / 100);
var totalOpExMonthly = monthlyTax + monthlyIns + vacancyCost + maintCost + mgmtCost;
var totalMonthlyExpenses = monthlyMortgage + totalOpExMonthly;
// 5. Returns
var monthlyCashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
var annualNOI = (rent * 12) – (totalOpExMonthly * 12); // Net Operating Income (excludes mortgage)
// Cash on Cash Return = Annual Pre-Tax Cash Flow / Total Cash Invested
// Assuming Closing Costs are ~3% of Price (Simplified for this calculator to be robust)
var estimatedClosingCosts = price * 0.03;
var totalCashInvested = downAmount + estimatedClosingCosts;
var cocReturn = (annualCashFlow / totalCashInvested) * 100;
// Cap Rate = Annual NOI / Purchase Price
var capRate = (annualNOI / price) * 100;
// 6. Display Results
document.getElementById('res_mortgage').innerText = "$" + monthlyMortgage.toFixed(2);
document.getElementById('res_expenses').innerText = "$" + totalMonthlyExpenses.toFixed(2);
document.getElementById('res_noi').innerText = "$" + (annualNOI / 12).toFixed(2);
var cfElement = document.getElementById('res_cashflow');
cfElement.innerText = "$" + monthlyCashFlow.toFixed(2);
// Style cash flow color based on profit/loss
if (monthlyCashFlow >= 0) {
cfElement.className = "rp-result-value rp-highlight";
} else {
cfElement.className = "rp-result-value rp-highlight-neg";
}
document.getElementById('res_coc').innerText = cocReturn.toFixed(2) + "%";
document.getElementById('res_cap').innerText = capRate.toFixed(2) + "%";
document.getElementById('resultsArea').style.display = "block";
}
Understanding Rental Property Cash Flow
Calculating cash flow is the fundamental step in evaluating any real estate investment. Cash flow represents the money left over after all expenses are paid. A positive cash flow indicates a profitable investment that puts money in your pocket every month, while negative cash flow implies a liability that drains resources.
This Rental Property Cash Flow Calculator allows investors to input specific financial details to determine the viability of a potential deal. By accounting for vacancy rates, maintenance reserves, and management fees—expenses often overlooked by beginners—you get a realistic picture of the property's performance.
Key Metrics Explained
1. Net Operating Income (NOI)
NOI is calculated by subtracting all operating expenses from the total revenue generated by the property. Crucially, NOI excludes mortgage payments and interest. It is a pure measure of the property's ability to generate income regardless of how it is financed.
2. Cash on Cash Return (CoC)
Perhaps the most popular metric for rental investors, Cash on Cash Return measures the annual return on the actual cash you invested. Unlike standard ROI, which might look at the total loan value, CoC focuses on the down payment and closing costs.
Formula: (Annual Cash Flow / Total Cash Invested) x 100
For example, if you invest $50,000 cash to buy a property and it generates $5,000 in net profit per year, your Cash on Cash return is 10%.
3. Cap Rate (Capitalization Rate)
The Cap Rate indicates the rate of return on a real estate investment property based on the income that the property is expected to generate. It is useful for comparing different properties without considering financing (cash deals).
Formula: (Net Operating Income / Current Market Value) x 100
Common Operating Expenses to Watch
- Vacancy Rate: No property is occupied 100% of the time. It is prudent to budget 5-10% of gross rent for vacancy periods.
- Maintenance & Repairs: Budgeting 5-10% for ongoing maintenance ensures you aren't surprised when a water heater breaks or a roof needs patching.
- Property Management: Even if you plan to manage it yourself, including a management fee (usually 8-10%) in your calculation ensures the deal still works if you decide to hire a professional later.
Use the calculator above to adjust variables like the down payment or rental income to see how they impact your bottom line. A successful real estate investor never relies on guesswork; they rely on math.