Calculate the potential value of a past stock investment.
Understanding the Stock Investment Calculator
This calculator helps you estimate the potential growth of an investment if you had purchased a specific stock at a particular time and held it until today. It compares the initial investment cost with the current market value of those shares.
How it Works: The Math Behind the Calculation
The calculation involves several steps:
Initial Investment Cost: This is calculated by multiplying the Purchase Price Per Share by the Number of Shares. This represents the total amount of money you would have spent initially.
Current Value of Investment: This is determined by multiplying the Current Price Per Share by the Number of Shares. This shows the market value of your shares at the present time.
Total Gain/Loss: The difference between the Current Value of Investment and the Initial Investment Cost gives you the total profit or loss on your hypothetical investment.
Percentage Gain/Loss: This is calculated by dividing the Total Gain/Loss by the Initial Investment Cost and then multiplying by 100 to express it as a percentage. This offers a standardized way to understand the performance of your investment relative to its initial cost.
Annualized Return: This metric estimates the average annual rate of return over the holding period. It's calculated by:
Determining the total holding period in years (difference between Current Date and Purchase Date).
Using the formula: ((Current Value / Initial Investment) ^ (1 / Number of Years)) - 1, then multiplying by 100. Handle cases where the holding period is less than a year or exactly zero.
Key Metrics You'll See:
Initial Investment: The total capital you would have initially put into the stock.
Current Market Value: The current worth of your shares based on today's stock price.
Total Profit/Loss: The absolute amount gained or lost.
Percentage Return: The overall return on investment as a percentage.
Annualized Return: The compounded annual growth rate (CAGR) of your investment, providing a standardized measure of performance over time.
Use Cases:
This calculator is useful for:
Educational Purposes: Understanding how stock prices fluctuate and the impact of holding periods.
Hypothetical Analysis: Evaluating the potential performance of stocks you are considering investing in.
Financial Planning: Backtesting investment strategies and visualizing potential outcomes.
Historical Comparison: Seeing how specific past investment decisions might have played out.
Disclaimer: Past performance is not indicative of future results. This calculator is for informational and educational purposes only and does not constitute financial advice. Stock market investments involve risk, and you may lose money.
function calculateInvestment() {
var purchasePrice = parseFloat(document.getElementById("purchasePrice").value);
var shares = parseFloat(document.getElementById("shares").value);
var purchaseDateInput = document.getElementById("purchaseDate").value;
var currentPrice = parseFloat(document.getElementById("currentPrice").value);
var currentDateInput = document.getElementById("currentDate").value;
var symbol = document.getElementById("symbol").value.toUpperCase(); // Get and capitalize symbol
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
// Input validation
if (isNaN(purchasePrice) || purchasePrice < 0 ||
isNaN(shares) || shares <= 0 ||
purchaseDateInput === "" ||
isNaN(currentPrice) || currentPrice < 0 ||
currentDateInput === "") {
resultDiv.innerHTML = "Please enter valid numbers for all fields and select dates.";
return;
}
var initialInvestment = purchasePrice * shares;
var currentMarketValue = currentPrice * shares;
var totalGainLoss = currentMarketValue – initialInvestment;
var percentageReturn = (totalGainLoss / initialInvestment) * 100;
// Calculate holding period in years
var purchaseDate = new Date(purchaseDateInput);
var currentDate = new Date(currentDateInput);
// Ensure current date is not before purchase date
if (currentDate 0 && years > 0) {
annualizedReturn = (Math.pow((currentMarketValue / initialInvestment), (1 / years)) – 1) * 100;
annualizedReturnText = "Annualized Return (CAGR): " + annualizedReturn.toFixed(2) + "%";
} else if (years === 0 && initialInvestment > 0) {
// If holding period is 0 days, we can't calculate annualized return meaningfully
annualizedReturnText = "Annualized Return (CAGR): N/A (Holding period too short)";
} else if (initialInvestment === 0) {
annualizedReturnText = "Annualized Return (CAGR): N/A (Initial investment was $0)";
} else {
annualizedReturnText = "Annualized Return (CAGR): N/A (Invalid dates or investment)";
}
var resultHTML = "";
if (symbol) {
resultHTML += "" + symbol + " Investment Summary";
}
resultHTML += "Initial Investment: $" + initialInvestment.toFixed(2) + "";
resultHTML += "Current Market Value: $" + currentMarketValue.toFixed(2) + "";
resultHTML += "Total Profit/Loss: $" + totalGainLoss.toFixed(2) + "";
resultHTML += "Percentage Return: " + percentageReturn.toFixed(2) + "%";
resultHTML += "" + annualizedReturnText + "";
resultDiv.innerHTML = resultHTML;
}