Calculations assume contributions are part of the initial cost basis for simplicity. For exact Money-Weighted Return (IRR) with irregular cash flows, detailed dates are required.
function calculateRateOfReturn() {
var startBal = document.getElementById('beginningBalance').value;
var endBal = document.getElementById('endingBalance').value;
var netContrib = document.getElementById('netContributions').value;
var years = document.getElementById('timePeriod').value;
// Validation
if (startBal === " || endBal === " || years === ") {
alert('Please fill in Beginning Balance, Ending Balance, and Time Period.');
return;
}
// Convert to numbers
var start = parseFloat(startBal);
var end = parseFloat(endBal);
var contrib = (netContrib === ") ? 0 : parseFloat(netContrib);
var time = parseFloat(years);
if (time <= 0) {
alert('Time Period must be greater than 0.');
return;
}
// Calculation Logic
// 1. Adjusted Cost Basis (Total Invested Amount)
var costBasis = start + contrib;
if (costBasis 0) {
annualizedReturn = (Math.pow((end / costBasis), (1 / time)) – 1) * 100;
} else {
// Handle total loss case
annualizedReturn = -100;
}
// Display Logic
var displayGain = netGain.toFixed(2);
var displayTotal = totalReturnPercent.toFixed(2) + '%';
var displayAnnual = annualizedReturn.toFixed(2) + '%';
// Add formatting for currency
document.getElementById('netGainResult').innerText = '$' + parseFloat(displayGain).toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
// Color coding for returns
var totalElem = document.getElementById('totalReturnResult');
var annualElem = document.getElementById('annualizedResult');
totalElem.innerText = displayTotal;
totalElem.style.color = totalReturnPercent >= 0 ? '#1a4d2e' : '#d32f2f';
annualElem.innerText = displayAnnual;
annualElem.style.color = annualizedReturn >= 0 ? '#1a4d2e' : '#d32f2f';
// Show results
document.getElementById('resultArea').style.display = 'block';
}
Understanding Your Fidelity Rate of Return
When reviewing your portfolio on platforms like Fidelity, understanding the specific "Rate of Return" displayed is crucial for evaluating investment performance. Unlike a simple savings account where the interest rate is static, investment returns fluctuate based on market conditions, dividends, and the timing of your cash flows.
Fidelity typically displays a Personal Rate of Return, which is often a Money-Weighted Rate of Return (MWRR). This metric takes into account not just the performance of the funds you hold, but also the timing and size of your deposits and withdrawals. This calculator helps you estimate that performance by comparing your starting balance and net contributions against your current portfolio value.
How the Calculation Works
To determine how well your money is working for you, this calculator uses three primary inputs:
Beginning Balance: The value of your portfolio at the start of the period (e.g., January 1st).
Ending Balance: The current value of your portfolio, including all growth, dividends reinvested, and market changes.
Net Contributions: The total amount of new money you added to the account minus any money you withdrew. This adjusts your "Cost Basis" so the calculator doesn't mistake a deposit for investment profit.
Total Return vs. Annualized Return
Total Cumulative Return tells you the raw percentage increase or decrease over the entire period selected. For example, if you invested $10,000 and it grew to $15,000 over 5 years, your total return is 50%.
Annualized Return (CAGR) is often the more useful metric for comparison. It smooths out the volatility and shows you what the compound annual growth rate would be. In the example above, a 50% total return over 5 years roughly equates to an 8.45% annualized return. This allows you to compare your portfolio's performance directly against benchmarks like the S&P 500 or annual inflation rates.
Why Your Personal Return Differs from Fund Performance
You may notice your "Personal Rate of Return" on Fidelity differs from the advertised performance of the mutual funds or ETFs you own. This is usually due to investor behavior. If a fund went up 20% in January, but you didn't buy it until February, your personal return will be lower. Conversely, if you added money during a market dip and the market recovered, your money-weighted return might be higher than the fund's time-weighted return.