Stock Average Calculator
Free stock average calculator that supports unlimited purchase entries. Calculate your average cost per share, cost basis, break-even price, and unrealized gain or loss. Works for stocks, ETFs, crypto, and any asset.
Stock Average Calculator
Enter each purchase to calculate weighted average cost, total investment, and break-even price.
Enter a current price to see unrealized gain or loss.
Frequently Asked Questions
What is average cost basis?
Average cost basis is the weighted average price you paid per share across all your purchases of a particular stock. It is calculated by dividing your total investment amount by the total number of shares owned. For example, if you bought 50 shares at $100 and 50 shares at $120, your average cost basis is ($5,000 + $6,000) / 100 = $110 per share. This figure is essential for calculating capital gains or losses when you sell.
How do you calculate average stock price?
Average stock price is calculated using the weighted average formula: Total Amount Invested / Total Shares Purchased. Each purchase is weighted by the number of shares bought at that price. For example, buying 200 shares at $50 and 100 shares at $80 gives an average of ($10,000 + $8,000) / 300 = $60 per share. A simple arithmetic average of $50 and $80 would give $65, which would be incorrect because it ignores the different quantities purchased.
What is dollar cost averaging?
Dollar cost averaging (DCA) is an investment strategy where you invest a fixed dollar amount at regular intervals, regardless of the stock price. When prices are low, you buy more shares; when prices are high, you buy fewer shares. Over time, this strategy can result in a lower average cost per share compared to making a single lump-sum purchase. DCA reduces the risk of investing a large amount at a market peak and removes emotional decision-making from the process.
Does selling affect average cost?
Selling shares does not change your average cost per share for the remaining shares under the average cost method. If your average cost is $50 per share and you sell some shares, the remaining shares still have a $50 average cost basis. However, the IRS allows different cost basis methods including FIFO (first in, first out), LIFO (last in, first out), and specific identification, which can result in different tax outcomes when you sell.
How does average cost impact taxes?
Your average cost basis directly determines your capital gain or loss when you sell shares. Capital gain = Sale Price - Average Cost Basis. A higher average cost means lower taxable gains. For example, selling shares at $150 with a $110 average cost results in a $40 per share gain, while a $130 average cost would yield only a $20 gain. Choosing the right cost basis method (average cost, FIFO, or specific identification) can significantly affect your tax bill.
Is dollar cost averaging better than lump sum?
Studies show that lump sum investing outperforms dollar cost averaging about two-thirds of the time because markets tend to rise over time. However, DCA provides psychological benefits by reducing the risk of investing everything at a market peak. DCA is particularly useful when you receive income regularly and invest it as it comes in. The best approach depends on your risk tolerance, time horizon, and whether you have a large sum available to invest immediately.
How do I track cost basis for multiple purchases?
To track cost basis across multiple purchases, record the date, number of shares, price per share, and any commissions for each transaction. Your brokerage typically tracks this automatically and reports it on Form 1099-B. For the average cost method, sum all purchase amounts and divide by total shares. For FIFO or specific identification, you need to track each lot individually. Using a stock average cost calculator simplifies this process significantly.
What is the formula for averaging down?
The averaging down formula is: New Average Price = Total Amount Invested ÷ Total Shares Owned. For example, if you buy 100 shares at $50 ($5,000) and then 100 more at $40 ($4,000), your new average is $9,000 ÷ 200 = $45.00 per share, down from $50.
Can I use this calculator for crypto and ETFs?
Yes! This stock average calculator works for any asset with a price per unit — stocks, ETFs, mutual funds, cryptocurrency, and even commodities. Simply enter your purchase price and quantity for each buy, and the calculator will compute your average cost basis.
How do commissions affect my average price?
Commissions and fees increase your true cost basis. If you buy 100 shares at $50 with a $10 commission, your actual cost per share is $50.10 ($5,010 ÷ 100). Our calculator includes an optional fee field to account for this, giving you a more accurate average cost.
How to Calculate Average Stock Price
The stock average calculator shows your weighted cost basis across multiple purchases. Use it to plan dollar-cost averaging, averaging down, and break-even levels after fees.
Table of Contents
Stock Average Formula
The calculator uses a weighted average, not a simple average of prices.
Total Shares
Add the shares from every purchase.
Total Investment
Sum each purchase price multiplied by shares, then add fees.
Average Cost Per Share
Divide total investment by total shares.
Break-Even Price
The break-even price is the same as your average cost per share.
Step-by-Step Calculation Example
Two buys at different prices produce a single weighted cost basis.
Initial Purchase
- 100 shares at $50.00 per share
- Investment: 100 x $50 = $5,000
Second Purchase
- 50 shares at $45.00 per share
- Investment: 50 x $45 = $2,250
Result
- Total Shares: 100 + 50 = 150
- Total Investment: $5,000 + $2,250 = $7,250
- Average Cost: $7,250 / 150 = $48.33 per share
- Break-Even Price: $48.33
Average Down Calculator Example
Buying more after a decline can lower your average cost if the new purchase is below your existing basis.
- You buy 200 shares of XYZ at $75 for $15,000.
- The stock drops to $50 and you buy 100 more shares for $5,000.
- Total investment becomes $20,000 across 300 shares.
- New average cost: $66.67 per share.
- Break-even price falls from $75 to $66.67.
Averaging down only helps when the original investment thesis still makes sense.
What Is Averaging Down in Stocks?
Averaging down means buying additional shares after a price decline so your overall cost basis moves lower. The goal is to need a smaller recovery before the position turns profitable.
The strategy can work well when a temporary selloff hits a fundamentally sound business, but it can also magnify losses if the company is deteriorating.
When to Average Down
- Fundamentals remain strong despite the price decline.
- The move looks temporary, such as a broad market selloff or sector rotation.
- Your original thesis still holds.
- The added shares will not make the position too large.
- You have enough time to wait for a recovery.
Risks of Averaging Down
- Catching a falling knife and buying too early.
- Adding to a business with weakening fundamentals.
- Overconcentrating your portfolio in one name.
- Ignoring a broken thesis just because the price looks cheaper.
- Failing to separate temporary volatility from real decline.
Understanding Cost Basis
Cost basis is the total amount you paid for the position, including purchase price and fees.
- Commissions and fees increase your true cost basis.
- The calculator works for stocks, ETFs, mutual funds, crypto, and other unit-priced assets.
- Average cost is the simplest basis method and is common for mutual funds and ETFs.
- Accurate basis tracking matters when you later calculate capital gains or losses.
Keep your purchase history even if your broker also tracks it for you.
Stock Average Cost Examples
These examples show why weighting and fees matter more than a simple price average.
Example 1: Averaging Down a Tech Stock
A position that started at a higher price is averaged down with later buys.
- 100 shares at $150.00 per share for $15,000.
- 50 shares at $120.00 per share for $6,000.
- 50 shares at $100.00 per share for $5,000.
- Total Shares: 200.
- Total Investment: $26,000.
- Average Cost: $130.00 per share.
The break-even price drops by 13.3% compared with the original entry.
Example 2: Dollar Cost Averaging Over 6 Months
A fixed monthly investment buys more shares when prices are lower.
- Month 1: $50.00 price, 10.00 shares, $500 invested.
- Month 2: $45.00 price, 11.11 shares, $500 invested.
- Month 3: $40.00 price, 12.50 shares, $500 invested.
- Month 4: $42.00 price, 11.90 shares, $500 invested.
- Month 5: $48.00 price, 10.42 shares, $500 invested.
- Month 6: $52.00 price, 9.62 shares, $500 invested.
The lower-price months contribute more shares, which drags the average cost below a simple arithmetic mean.
Example 3: Impact of Fees on Average Price
Small fees can move the real cost basis, especially on smaller orders.
- Without fees: 100 shares at $50 = $5,000 total.
- With a $9.99 fee: 100 shares at $50 = $5,009.99 total.
- Across 10 trades: 1,000 shares at $50 plus $99.90 in fees = $50,099.90 total.
- Average cost stays around $50.10 per share once fees are included.
Always include fees if you want a cost basis that matches your broker statement.