.roi-calculator-widget {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 650px;
margin: 20px auto;
padding: 25px;
background: #ffffff;
border: 1px solid #e0e0e0;
border-radius: 8px;
box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}
.roi-calculator-widget h2 {
text-align: center;
color: #2c3e50;
margin-bottom: 25px;
font-size: 24px;
}
.roi-input-group {
margin-bottom: 20px;
}
.roi-input-group label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #34495e;
}
.roi-input-wrapper {
position: relative;
display: flex;
align-items: center;
}
.roi-input-wrapper input {
width: 100%;
padding: 12px 15px;
font-size: 16px;
border: 1px solid #bdc3c7;
border-radius: 4px;
transition: border-color 0.2s;
}
.roi-input-wrapper input:focus {
border-color: #3498db;
outline: none;
}
.roi-prefix, .roi-suffix {
position: absolute;
color: #7f8c8d;
font-weight: 500;
}
.roi-prefix { left: 12px; }
.roi-suffix { right: 12px; }
.roi-with-prefix input { padding-left: 30px; }
.roi-with-suffix input { padding-right: 60px; }
.roi-btn {
width: 100%;
padding: 14px;
background-color: #27ae60;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.2s;
margin-top: 10px;
}
.roi-btn:hover {
background-color: #219150;
}
.roi-results {
margin-top: 25px;
padding: 20px;
background-color: #f8f9fa;
border-radius: 6px;
display: none;
border-left: 5px solid #27ae60;
}
.roi-result-row {
display: flex;
justify-content: space-between;
margin-bottom: 12px;
padding-bottom: 12px;
border-bottom: 1px solid #e9ecef;
}
.roi-result-row:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
}
.roi-result-label {
color: #555;
font-size: 15px;
}
.roi-result-value {
font-weight: 700;
color: #2c3e50;
font-size: 18px;
}
.roi-highlight {
color: #27ae60;
font-size: 22px;
}
.roi-content {
max-width: 800px;
margin: 40px auto;
font-family: inherit;
line-height: 1.6;
color: #333;
}
.roi-content h2 {
color: #2c3e50;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
margin-top: 40px;
}
.roi-content h3 {
color: #34495e;
margin-top: 25px;
}
.roi-content ul {
margin-bottom: 20px;
}
.roi-content li {
margin-bottom: 10px;
}
.roi-formula-box {
background: #f1f8ff;
padding: 15px;
border-radius: 4px;
font-family: monospace;
margin: 20px 0;
border: 1px solid #d1e5ff;
}
function calculateInvestmentReturn() {
// Get input values using var
var initialInput = document.getElementById('initialInvestment');
var finalInput = document.getElementById('finalValue');
var timeInput = document.getElementById('timePeriod');
var resultDiv = document.getElementById('roiResult');
var initial = parseFloat(initialInput.value);
var final = parseFloat(finalInput.value);
var years = parseFloat(timeInput.value);
// Validation
if (isNaN(initial) || isNaN(final) || isNaN(years)) {
alert("Please enter valid numbers for all fields.");
return;
}
if (initial <= 0) {
alert("Initial investment must be greater than zero.");
return;
}
if (years = 0) {
cagrElement.style.color = "#27ae60";
profitElement.style.color = "#2c3e50";
} else {
cagrElement.style.color = "#c0392b";
profitElement.style.color = "#c0392b";
}
// Show results
resultDiv.style.display = 'block';
}
How to Calculate Rate of Return on Investment Over Time
Calculating the performance of an investment is fundamental to financial planning. While knowing how much money you made in total (net profit) is useful, understanding the Rate of Return over time allows you to compare different investments effectively, regardless of how long you held them.
Why "Over Time" Matters
If Investment A gains 20% in 1 year, and Investment B gains 20% in 5 years, Investment A is significantly better. A simple percentage gain calculation ignores the time factor. To solve this, investors use the Annualized Return, often referred to as the CAGR (Compound Annual Growth Rate).
The Core Formulas
1. Absolute Rate of Return (Total ROI)
This calculates the total percentage growth from start to finish, ignoring the duration.
Total ROI = ((Final Value – Initial Investment) / Initial Investment) × 100
2. Annualized Rate of Return (CAGR)
This calculates the geometric progression ratio that provides a constant rate of return over the time period. It smooths out the volatility of returns over a period of years.
CAGR = ( (Final Value / Initial Investment) ^ (1 / Number of Years) ) – 1
Example Calculation
Let's say you invested $10,000 in a mutual fund.
- Initial Investment: $10,000
- Final Value: $15,000
- Time Period: 3 Years
Step 1: Calculate Total Return
($15,000 – $10,000) / $10,000 = 0.50 or 50%.
Step 2: Calculate Annualized Return (CAGR)
($15,000 / $10,000) ^ (1 / 3) – 1
(1.5) ^ 0.3333 – 1
1.1447 – 1 = 0.1447 or 14.47%.
Even though your money grew by 50% total, your money was compounding at an annual rate of roughly 14.5%.
Key Metrics Explained
- Initial Investment: The principal amount of cash you put into the asset at the beginning (t=0).
- Final Portfolio Value: The current market value of the asset or the amount you sold it for. This should include any dividends or interest reinvested.
- Investment Duration: The holding period measured in years. For partial years (e.g., 6 months), use decimals (0.5 years).
- Net Profit: The absolute dollar amount gained or lost.
Limitations
This calculator assumes a "lump sum" investment. If you made regular monthly contributions (Dollar Cost Averaging), a more complex Internal Rate of Return (IRR) calculation would be required. However, for evaluating the performance of a single asset purchase (like a house, a specific stock purchase, or a vintage car) over a specific holding period, CAGR is the gold standard metric.