Stock Average Calculator
Average down or up with confidence: combine every purchase lot into one average cost per share, then see your breakeven price, current value and profit or loss — fees included.
- Average cost = total amount invested ÷ total shares owned. Two lots of 10 shares at $100 and $50 average to $75 — not $75 by luck, by math.
- Fees raise your breakeven: $20 of commission on that example lifts it from $75.00 to $76.00 a share.
- Add a planned purchase in Advanced options to preview your new average before you place the order.
Average your stock
Enter each purchase lot, then the current price.
Advanced options — more lots, fees & targets
All trading commissions added together. Fees are included in your average cost and breakeven by default.
See what your position would be worth — and gain — at a price you choose.
Fees are already included in the average cost and breakeven with their default ($0) — open Advanced options to add lots 3–5, commissions, a planned purchase, or a target price.
Key takeaways
- Average cost = total invested ÷ total shares. 10 shares at $100 plus 10 at $50 = $1,500 ÷ 20 = $75 per share.
- Your breakeven is your average cost — including fees. With $20 of commission, the example breakeven rises to $76.
- Averaging down lowers your average but raises your exposure. Buying more of a falling stock only helps if the thesis is still intact.
- Profit / loss is measured against total cost, not the last price you paid. At $80, the $75-average position above is up $100 (+6.67%).
- Preview before you buy: enter a planned purchase in Advanced options to see your new average before committing money.
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The average-cost formula
For every lot you bought, multiply shares by price, add the results together, add any fees, and divide by the total number of shares:
Average cost = (Lot 1 shares × Lot 1 price + Lot 2 shares × Lot 2 price + … + fees) ÷ total shares.
That is the whole formula. There is no weighting trick beyond it — a lot of 100 shares at $10 counts ten times as much as a lot of 10 shares at $20, because it is ten times as much money.
Worked examples
Example 1 — simple average: 10 shares at $100 ($1,000) and 10 shares at $50 ($500). Total $1,500 over 20 shares = $75.00 average. At a current price of $80 the position is worth $1,600 — a $100 gain, or 6.67%.
Example 2 — with fees: add $20 of total commission and the cost becomes $1,520, so the average and breakeven both become $76.00. Ignore fees and you will think you are profitable $1 per share too early.
Example 3 — planned purchase: from the $75 average above, buying 20 more shares at $90 adds $1,800, giving $3,300 over 40 shares = $82.50 new average. The purchase pulls the average up toward $90, because it is the biggest lot so far.
Fees and breakeven
Your breakeven price is exactly your average cost including fees: sell above it and you profit, sell below it and you lose (before any selling fees and taxes). If your broker charges per trade, add every trade’s commission together in the fees field — five $5 trades are $25, not $5.
Some brokers advertise “free” trades but earn from payment for order flow or currency conversion. If you paid a spread or an FX fee, include a reasonable estimate so the breakeven stays honest.
Averaging down vs averaging up
Averaging down means buying more as the price falls, which lowers your average and lets a smaller recovery turn you profitable. Averaging up means adding as the price rises, which raises your average but follows strength. Neither is automatically smart: averaging down into a broken business is “catching a falling knife”, while averaging up into a bubble adds exposure at the top.
The useful question is never “does this lower my average?” — it is “would I buy this stock fresh today, at this price, with this money?” If the answer is no, averaging down is just defending an old decision.
Risks and mistakes
- Forgetting fees — the most common error; it understates breakeven on every trade.
- Counting only the last lot — your broker’s “average price” already weights all lots; a simple mean of prices ($100 + $50) ÷ 2 = $75 only matches by accident when lots are equal size.
- Ignoring splits and dividends — a 2-for-1 split halves your per-share average (and doubles share count); reinvested dividends add shares at their reinvestment price.
- Position size creep — repeated averaging down can quietly turn one stock into most of your portfolio. Check the total invested, not just the average.
A note on taxes
This calculator shows pre-tax profit and loss. In many countries, selling triggers capital gains tax, and the cost basis rules (FIFO, average cost, or specific lots) depend on your jurisdiction and broker settings. Keep your own lot records — this page stores nothing — and confirm the tax treatment with a qualified adviser before selling.
How it works
Three steps, no sign-up.
Shares and price for each purchase — two lots are shown, three more live in Advanced options.
Include commissions, a planned purchase, or a target sell price to see the full picture.
Your average cost, breakeven, current value and profit or loss update below.
Averaging down versus averaging up: the same maths, opposite bets
Averaging down buys more shares as the price falls, lowering the average cost per share. Averaging up buys more as the price rises, raising the average cost but adding to a position that is proving itself. The arithmetic is identical — total cost divided by total shares — and the difference is entirely in the investment judgement. Averaging down expresses the belief that the fall is temporary and the shares are cheap; averaging up expresses the belief that the rise will continue and the position deserves more capital. Both beliefs can be wrong, and the average cost figure does not distinguish between them.
The risk of averaging down is concentration: each purchase increases the exposure to a single company, and a fall that continues turns a small losing position into a large one. The discipline that governs it is position sizing — deciding in advance the maximum the position will ever be, and the price levels at which further purchases stop regardless of how cheap the shares look. Averaging up carries the opposite risk: buying at ever-higher prices into a rise that reverses, leaving a position bought near the top. Neither technique is inherently sound or unsound; both are ways of implementing a view about a company, and the view, not the averaging, is what should be examined.
Record-keeping: average cost, total cost, and the tax lots behind them
The average cost per share is a summary, and summaries discard information. Behind it sit the individual purchases — the tax lots — each with its own date, price, and quantity. Tax treatment depends on the lots, not the average: which lots are sold determines the gain or loss, the holding period, and the tax rate, and in several jurisdictions the default identification method and the methods available for choosing lots are regulated. Keep the lot-level record even when the average is the figure you watch day to day, because the average cannot reconstruct the lots, and the tax return needs the lots.
Two further records matter. First, corporate actions — splits, bonus issues, mergers, spin-offs — change the share count and the cost basis without any purchase, and the average must be recomputed after each one. A 2-for-1 split halves the average cost per share and doubles the share count; the total cost is unchanged. Second, dividends reinvested are purchases at the reinvestment price, and they raise both the share count and the total cost. A record that omits reinvested dividends understates the cost basis and overstates the gain when the position is sold. The calculator on this page computes the average from the purchases entered; the lot-level record is the investor’s responsibility, and it should be kept outside any single tool.
Frequently asked questions
Straight answers, with worked examples.
How do you calculate stock average price?
Add up the cost of every lot (shares × price), add any fees, and divide by total shares. Example: 10 shares at $100 plus 10 at $50 = $1,500 ÷ 20 = $75 per share.
What is the breakeven price of a stock?
Your average cost including fees. Sell above it and you profit; sell below it and you lose (before selling fees and taxes). In the example above with $20 of fees, breakeven is $76, not $75.
Does averaging down always help?
No. It lowers your average cost, but it also increases how much money you have in that stock. It only helps if the stock recovers — if the business is broken, you have simply bought more of a loser.
How do fees change my average?
They add to total cost. $20 of commission on a $1,500 position over 20 shares raises the average by $1.00, from $75 to $76.
What happens to my average after a stock split?
A 2-for-1 split doubles your shares and halves your per-share average, so total cost is unchanged: 20 shares at $75 become 40 shares at $37.50.
Is this calculator’s result my taxable gain?
No — it shows pre-tax profit and loss. Tax depends on your country’s rules and your broker’s cost-basis method, so check with a tax adviser before selling.
How do you calculate average stock price after buying more shares?
Total cost divided by total shares. Buy 100 shares at $50 ($5,000), then 100 more at $40 ($4,000): average cost = $9,000 ÷ 200 = $45 per share. The average sits between the two purchase prices, weighted by the number of shares bought at each.
Does averaging down always reduce risk?
No. It reduces the average cost per share but increases the total amount invested in one company, concentrating risk. If the price keeps falling, the loss grows with each purchase. Set a maximum position size in advance and stop averaging down at a predetermined level, regardless of how cheap the shares appear.