Calculate the total value and gain/loss of your stock investments.
Understanding Your Stock Portfolio Performance
A stock portfolio calculator is a vital tool for any investor looking to understand the performance of their investments. It helps you track the total value of your holdings, calculate your unrealized gains or losses, and make informed decisions about your portfolio. This calculator focuses on a single stock holding for simplicity, but the principles can be extended to an entire portfolio.
How the Calculator Works:
The calculator uses basic arithmetic to determine the performance of your stock investment. It requires the following inputs:
Stock Symbol: The ticker symbol of the company whose stock you own (e.g., AAPL for Apple Inc., GOOG for Alphabet Inc.).
Purchase Price per Share: The price you paid for each share of the stock, excluding any brokerage fees.
Number of Shares: The total quantity of shares you own for this specific stock.
Current Price per Share: The current market price of one share of the stock.
The Calculations:
The calculator performs the following essential calculations:
Total Purchase Cost: This is the total amount of money you initially spent to acquire the shares.
Total Purchase Cost = Purchase Price per Share × Number of Shares
Current Portfolio Value: This represents the total market value of your shares at the current price.
Current Portfolio Value = Current Price per Share × Number of Shares
Unrealized Gain/Loss: This is the difference between your current portfolio value and your total purchase cost. A positive number indicates a gain, while a negative number indicates a loss.
Unrealized Gain/Loss = Current Portfolio Value - Total Purchase Cost
Percentage Gain/Loss: This expresses the gain or loss as a percentage of your initial investment.
Percentage Gain/Loss = (Unrealized Gain/Loss / Total Purchase Cost) × 100%
Use Cases:
Tracking Individual Stock Performance: Easily see how well a particular stock you own is performing.
Assessing Investment Decisions: Evaluate whether your initial decision to buy a stock was profitable.
Portfolio Diversification Analysis: While this calculator is for a single stock, you can use it repeatedly for each holding to understand the contribution of each to your overall portfolio's performance.
Quick Valuation: Get an immediate estimate of your investment's current worth.
By understanding these metrics, investors can make more informed decisions about when to buy, sell, or hold their stock investments. Remember that this calculator does not account for brokerage fees, dividends, taxes, or inflation, which can all impact your actual returns.
function calculatePortfolio() {
var purchasePrice = parseFloat(document.getElementById("purchasePrice").value);
var numberOfShares = parseInt(document.getElementById("numberOfShares").value);
var currentPrice = parseFloat(document.getElementById("currentPrice").value);
var stockSymbol = document.getElementById("stockSymbol").value.trim().toUpperCase();
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
// Input validation
if (isNaN(purchasePrice) || purchasePrice < 0) {
resultDiv.innerHTML = "Please enter a valid positive purchase price per share.";
return;
}
if (isNaN(numberOfShares) || numberOfShares <= 0) {
resultDiv.innerHTML = "Please enter a valid positive number of shares.";
return;
}
if (isNaN(currentPrice) || currentPrice < 0) {
resultDiv.innerHTML = "Please enter a valid positive current price per share.";
return;
}
if (stockSymbol === "") {
resultDiv.innerHTML = "Please enter a stock symbol.";
return;
}
var totalPurchaseCost = purchasePrice * numberOfShares;
var currentPortfolioValue = currentPrice * numberOfShares;
var unrealizedGainLoss = currentPortfolioValue – totalPurchaseCost;
var percentageGainLoss = (totalPurchaseCost === 0) ? 0 : (unrealizedGainLoss / totalPurchaseCost) * 100; // Avoid division by zero
var resultHtml = "