Stock Average Calculator
Your average cost per share is the total amount you paid divided by the total number of shares you own. Add each buy below to get your average share price, your total cost basis, and, if you enter the current price, your unrealized profit or loss.
Thinking about adding to a position? Upload the chart and Lynx AI gives you a structured read on the levels and a long or short bias before you average in.
Get ProHow to use this calculator
- Enter your first buy. Add the number of shares and the price you paid for your first purchase.
- Add every other lot. Use "Add a buy" for each additional purchase at a different price. Include fees in the price if you want them counted.
- Read your average cost. The tool returns your average cost per share, your total share count, and your total cost basis.
- Add the current price. Optional. Enter the current market price to see position value and unrealized profit or loss.
The average cost formula
Average cost per share = total amount paid ÷ total shares owned
Total amount paid is the sum of (shares × price) across every buy. Because it is share-weighted, a large purchase pulls the average toward its price far more than a small one. This is why a single big top-up changes your average more than three small ones at the same price.
Worked example with three lots
You build a position in three separate purchases:
- 10 shares at $100 = $1,000
- 15 shares at $90 = $1,350
- 25 shares at $80 = $2,000
- Total = 50 shares for $4,350
- Average cost per share = $4,350 ÷ 50 = $87.00
At a current price of $95, those 50 shares are worth $4,750, an unrealized gain of $400, about 9.2% on the amount invested. Note that the third lot, the largest one, is what pulled the average from $94 down to $87.
Where fees fit in
Commissions and transaction fees are part of what you actually paid, so strictly speaking they belong in your cost basis. This calculator does not have a separate fee field, so add the fee into the price of the lot it applies to. Buying 10 shares at $100 with a $5 commission means you paid $1,005 for 10 shares, so enter $100.50 as the price. On small positions with per-trade commissions this is not a rounding detail.
Averaging down vs dollar-cost averaging
These two get confused because both lower an average price, but the decision behind them is not the same.
- Averaging down is a discretionary decision to buy more of something after it has fallen. It lowers your break-even price, but it also concentrates more capital into a position that is currently going against you. If the reason you bought is no longer true, a lower average cost does not fix that: it just makes the mistake bigger.
- Dollar-cost averaging is a schedule, not a reaction. You invest a fixed amount at fixed intervals whatever the price does, which spreads your entries across time and removes the timing decision. It naturally buys more shares when prices are lower, but that is a by-product of the rule rather than a call on the chart. Read dollar-cost averaging explained for the full comparison.
What your average cost does and does not tell you
Your average cost is a cost basis, not a target. It tells you the price at which the position is flat and it is what a tax authority will compare your sale proceeds against. It says nothing about where the price should go next, and the market does not know or care what you paid. Deciding to hold a losing position purely because the price is below your average is the anchoring bias doing the work, not analysis. If you want to add to a position, size the new lot against your account risk first with the position size calculator, and check the setup is worth taking with the risk/reward calculator.
How an AI chart reader uses this
Knowing your average is arithmetic. Deciding whether to add is a chart question. If you upload a screenshot to Bullynx, Lynx reads the visible structure, the levels where price has previously reacted, and whether the current move is a pullback inside a trend or a broken structure, then says what would invalidate that read. It works from what is in the image, so it does not know your cost basis and it does not predict prices. Read the walkthrough in the stock average calculator guide.
Frequently asked questions
How do you calculate the average cost of a stock?
Multiply the shares by the price for each purchase, add those amounts together to get the total spent, then divide by the total number of shares you own. That figure is your average cost per share. It is a share-weighted average, so a large buy pulls it further than a small one.
How do you calculate the average cost per share across multiple buys?
Use the same formula and simply add one line per purchase. Buying 10 shares at 100 and 15 shares at 90 gives 1,000 plus 1,350, which is 2,350 spent for 25 shares, so the average price per share is 94. The calculator on this page does this for as many lots as you enter.
What is cost basis?
Cost basis is the total amount you paid for a holding across every purchase. Per-share cost basis is that total divided by your share count, which is the same number this calculator calls your average cost per share. It is the reference point for measuring gains or losses and is used for tax reporting in many jurisdictions.
What does averaging down mean?
Averaging down means buying more of a holding after the price has fallen, which lowers your average cost per share and lowers the price at which the position breaks even. It also increases your exposure to a position that is already losing, so the lower average price is bought with more risk, not less.
Is the average share price the same as VWAP?
No. Your average share price is weighted by the shares you personally bought. VWAP, the volume-weighted average price, is weighted by the whole market volume traded over a session and is a market indicator, not a record of your own entries. The two only match by coincidence.
Does this calculator account for fees or taxes?
Not directly. It uses the share counts and prices you enter. If you want commissions included, add the fee into the buy price for that lot, or add it to the total spent before dividing. The result is an estimate for your own planning and is not tax advice.
Is my average cost a price target?
No. Your average cost tells you where the position breaks even, nothing about where the price is likely to go. A holding does not become a better one because your average is lower, and the market has no memory of what you paid.
Related calculators
- Position size calculator: how many shares to buy so a loss costs a fixed percentage of your account.
- Risk/reward calculator: your R:R ratio and the win rate you need to break even.
- Pip value calculator: what one pip is worth on a forex position.
- VWAP explained: the market-wide volume-weighted average price, and why it is not your average.
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Educational only. Not financial advice. NFA. This tool does not account for fees or taxes and is not tax advice. Read the full risk disclosure.