Stock Average Calculator: Find Your Average Cost Per Share
This stock average calculator finds the average price you paid for a stock bought in several purchases. Enter the shares, price, and any fees for each buy, and it shows your average cost per share, total shares, total invested, and, if you add a current price, an estimate of your unrealized gain or loss.
Stock Average Cost Calculator
Average cost per share
Under these purchases, your 150 shares cost an estimated $7,000.00 in total, an average of $46.67 per share including fees. At $45.00 a share, the position could show an unrealized loss of $250.00 (-3.6%).
- Total shares
- Total invested (including fees)
- Total fees
- Average cost before fees
- Break-even price
- Current value
- Unrealized gain or loss
Purchase Prices Compared With Your Average
| Purchase | Shares | Price | Fees | Cost | Share of Position |
|---|---|---|---|---|---|
| 1 | 100 | $50.00 | $0.00 | $5,000.00 | 66.7% |
| 2 | 50 | $40.00 | $0.00 | $2,000.00 | 33.3% |
| Total | 150 | $46.67 avg | $0.00 | $7,000.00 | 100% |
Assumptions
- Average cost includes the fees you enter, so it equals the break-even price per share.
- All purchases are treated as one position in the same stock, with no sales in between.
- Stock splits, dividends, and reinvested dividends are not adjusted for.
- Taxes are not included, and tax lots may be tracked differently by your broker.
- The gain or loss is unrealized and changes with the market price.
Educational estimate only. This calculator uses the assumptions you enter to illustrate a possible financial outcome. It does not predict future investment performance, interest rates, inflation, taxes, market prices, or financial results. Actual outcomes may differ.
How the Stock Average Calculator Works
Each purchase adds its cost and its shares to the position. The average cost is the total cost divided by the total shares:
Total cost = Sum of (shares × price + fees)
Average cost per share = Total cost ÷ Total shares
For example, buying 100 shares at $50 and later 50 shares at $40 costs $5,000 plus $2,000, or $7,000 for 150 shares. The average cost is $7,000 ÷ 150, about $46.67 per share. The average sits closer to $50 than to $40 because more shares were bought at the higher price. These are Fin Loom calculations.
A simple average of the two prices would give $45, which is wrong whenever the purchases are different sizes. Weighting by shares is what makes the result match what you paid.
Why Fees Change the Result
Commissions and other purchase fees add to what you paid, so the calculator includes them in the total cost. With fees included, the average cost per share is also your break-even price: the share price at which selling every share would return exactly what you put in, before any selling costs or taxes.
The results also show the average cost before fees, so you can see how much the fees added. On small purchases, even a few dollars of fees can move the break-even price noticeably.
Averaging Down and Averaging Up
Buying more shares after a price drop lowers the average cost, which is often called averaging down. Buying after a price rise raises it, called averaging up. The calculator shows the effect of either before or after you trade, and the bar chart compares each purchase price with the resulting average.
A lower average cost does not by itself make a position safer or more likely to recover. It also increases the money committed to one company. Weighing the business itself, as covered in stock analysis fundamentals, and the size of the position, as covered in stock risk metrics, helps put a lower average in context. Fin Loom does not recommend buying, selling, or holding any security.
Limits of a Stock Average Calculator
The calculator treats every purchase as part of one position with no sales in between. It does not adjust for stock splits, reinvested dividends, or corporate actions, which brokers handle in their own records. For taxes, brokers and the IRS track cost basis by individual lot, so the tax result of a sale can differ from what one blended average suggests.
More Fin Loom Calculators
This tool is part of Fin Loom's set of financial calculators and reference tools, which covers inflation, compound interest, investment growth, dividends, withdrawals, capital gains tax, and stock trades.
Frequently Asked Questions
How Do You Calculate the Average Cost of a Stock?
Add the cost of every purchase, including fees, then divide by the total number of shares you bought. That gives a share-weighted average rather than a simple average of prices.
Does the Average Cost Include Fees?
Yes, if you enter them. Fees are added to total cost, so the average cost per share also equals your break-even price before selling costs and taxes.
What Is a Break-Even Price?
It is the share price at which the position's market value equals what you paid, including purchase fees. Selling costs and taxes would raise the true break-even point.