Stock Average Calculator
Average cost basis across up to five purchases, in shares or dollars, with the current gain or loss, the break-even price and what averaging down really does.
Stock Average Calculator: with the default inputs, average cost per share is $38.5714.
Dollars is the true dollar-cost-averaging case: a fixed amount each month buys more shares when the price is low.
- In words
- 350 shares at an average of $38.5714, $13,500.00 invested and now worth $15,750.00 — up $2,250.00 (16.67%).
- Total shares
- 350
- Total invested
- $13,500.00
- Current value
- $15,750.00
- Unrealized gain or loss
- $2,250.00
- Return on cost
- 16.67%
- Break-even price
- $38.5714The price at which the whole position is worth exactly what you paid, commissions included.
- Move needed to break even
- -14.29%
- Highest price paid
- $50.00
- Lowest price paid
- $30.00
- Simple average of the prices paid
- $40.0000The unweighted mean — shown only to make the point that it is not your cost basis.
Assumptions
- Average cost basis, not FIFO or specific-lot identification.
- Commissions are added to cost basis, once per purchase entered.
- No adjustment for stock splits, dividends, return of capital or wash sales.
- Return on cost is a simple percentage, not annualized.
| Purchase | Price paid | Shares | Cost | % of shares | Worth now |
|---|---|---|---|---|---|
| #1 | $50.0000 | 100 | $5,000.00 | 28.6% | $4,500.00 |
| #2 | $40.0000 | 100 | $4,000.00 | 28.6% | $4,500.00 |
| #3 | $30.0000 | 150 | $4,500.00 | 42.9% | $6,750.00 |
Cost basis is weighted by shares, not by the number of purchases. The lot that bought the most shares moves the average the most.
How this is worked out
The formula
Shares (dollars mode) = amount invested ÷ price paid Total cost = Σ (shares × price) + commissions Total shares = Σ shares Average cost per share = total cost ÷ total shares Break-even price = average cost per share Unrealized gain = total shares × current price − total cost Return on cost = gain ÷ total cost
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Each purchase entered as
- Dollars is the true dollar-cost-averaging case: a fixed amount each month buys more shares when the price is low.Number of shares · Dollars invested
- Purchase 1 — shares or $
- A number.0 or more · defaults to 100
- Purchase 1 — price per share
- A number.in dollars · 0 or more · defaults to 50
- Purchase 2 — shares or $
- A number.0 or more · defaults to 100
- Purchase 2 — price per share
- A number.in dollars · 0 or more · defaults to 40
- Purchase 3 — shares or $
- A number.0 or more · defaults to 150
- Purchase 3 — price per share
- A number.in dollars · 0 or more · defaults to 30
- Purchase 4 — shares or $(under More options)
- A number.0 or more · defaults to 0
- Purchase 4 — price per share(under More options)
- A number.in dollars · 0 or more · defaults to 0
- Purchase 5 — shares or $(under More options)
- A number.0 or more · defaults to 0
- Purchase 5 — price per share(under More options)
- A number.in dollars · 0 or more · defaults to 0
- Current price
- A number.in dollars · 0 or more · defaults to 45
- Commission per trade(under More options)
- Added to cost basis, which is where it belongs — it raises your break-even price.in dollars · 0 or more · defaults to 0
What you get back
- Average cost per sharemain answer
- In words
- Total shares
- Total invested
- Current value
- Unrealized gain or loss
- Return on cost
- Break-even price
- The price at which the whole position is worth exactly what you paid, commissions included.
- Move needed to break even
- Highest price paid
- Lowest price paid
- Simple average of the prices paid
- The unweighted mean — shown only to make the point that it is not your cost basis.
What this assumes
- Average cost basis, not FIFO or specific-lot identification.
- Commissions are added to cost basis, once per purchase entered.
- No adjustment for stock splits, dividends, return of capital or wash sales.
- Return on cost is a simple percentage, not annualized.
About this calculator
Your average cost per share is total dollars in divided by total shares held — not the average of the prices you paid. The distinction matters as soon as the purchases are different sizes. Buy 100 shares at $50, 100 at $40 and 150 at $30 and the simple average of the prices is $40.00, while your actual cost basis is $38.57, because the biggest purchase happened at the lowest price.
Two ways to enter it, and they behave differently
Shares mode is for recording what actually happened: you bought a specific number of shares at a specific price. Dollars mode is the true dollar-cost-averaging case — a fixed $500 a month, whatever the price. That fixed amount automatically buys more shares when the price is low and fewer when it's high, which is the entire mechanism behind DCA: it pulls your average cost below the simple average of the prices you paid, with no market timing required.
Break-even is further away than it looks
The break-even price is just your average cost, and getting back to it is always a bigger percentage than the fall that got you there. A stock that drops 33% has to rise 50% to recover; down 50% needs 100%. The move needed to break even output does that arithmetic, and it's a useful antidote to the feeling that a small bounce will make you whole.
What averaging down does — and what it doesn't
Buying more as a price falls lowers your average cost. That is arithmetic, and this calculator will confirm it every time. What it does not do is improve the investment. Lowering the average cost also increases the amount of money you have in a position that is currently going the wrong way, which is the same trade twice with more conviction and less diversification. The honest test is the one a fund manager applies: if I held no shares today, would I buy this at this price? If the answer is yes, buy — but buy because of that, not because it lowers a number on a screen. If the answer is no, the low average cost is a consolation, not a reason.
Reading the results
Total invested includes commissions, which belong in cost basis — they raise your break-even price and, in a taxable account, reduce your eventual gain. Return on cost is the simple percentage gain, not an annualized return: two positions both up 20% are not equivalent if one took nine months and the other took nine years. For a time-weighted figure, use the CAGR calculator.
Where it misleads
This computes a single average cost basis, which is how mutual funds are usually reported and how many brokers display an equity position. For US tax purposes on individual shares, the default is FIFO unless you specifically identify lots at the time of sale, and specific identification can be worth real money — selling your highest-cost lots first defers tax. The average shown here is the right number for "how am I doing"; it is not necessarily the number that goes on your tax return. It also ignores dividends received, stock splits (adjust both share counts and prices), and any wash-sale adjustments.
Frequently asked questions
▸How do I calculate my average cost per share?
Total dollars invested divided by total shares owned, including commissions. It is not the average of the prices you paid — that only matches when every purchase was the same number of shares.
▸Does averaging down reduce my risk?
No. It reduces your average cost and increases your position size in something that is falling. The test is whether you'd buy at today's price holding nothing; if you wouldn't, a lower average cost isn't a reason to.
▸Why does a stock that fell 50% need to rise 100% to break even?
Because the gain is measured against the smaller base. $100 falling to $50 is −50%; $50 back to $100 is +100%. This asymmetry is why avoiding large drawdowns matters more than capturing large gains.
▸Is average cost the same as my tax cost basis?
Not necessarily. Average cost is standard for mutual funds, but for individual shares the US default is FIFO unless you identify specific lots at the time of sale. Specific identification often produces a better tax result, so check with your broker before selling.
▸Should I include dividends in my cost basis?
Dividends received in cash don't change cost basis. Dividends reinvested do — each reinvestment is a new purchase at that day's price, so enter it as one of the purchase lines.
Put this calculator on your own site
A working stock average, free for any site, with no ads and no sign-up. It resizes to fit wherever you paste it and updates itself as this page improves.
Paste this anywhere. It works on any site, carries no ads, never expires, and always shows the current version.
Stock Average Calculator by CalculateItNow
The page's own title. The clearest description of what the link leads to.
The credit line sits outside the widget on purpose, so it is a real link on your page rather than one buried in a frame. Please keep it — it is what pays for CalculateItNow staying free and ad-free. The script only resizes the widget to fit its contents; drop it and the widget still works.
Browse every calculator widget·How to add it to WordPress, Squarespace or Wix
Related calculators
The questions people ask next to a stock average.
Dividend yield, yield on cost, payout ratio, dividend cover and free-cash-flow payout — the four numbers that say whether a yield is safe or a warning.
Convert a nominal interest rate into annual percentage yield and back, at any compounding frequency — plus the APY-vs-APR distinction people get wrong.
Project investment growth with monthly contributions, annual raises, fund expense ratios and inflation — with a yearly split of what you invested vs. earned.
Compound annual growth rate from a start value, end value and years — or the end value from a rate — with total growth and a year-by-year table.
Return on investment and annualized ROI from what you put in, what you got back and how long it took, with the work shown and ROI vs CAGR vs IRR explained.
See how a lump sum plus regular deposits grows with daily, monthly, quarterly or annual compounding — with a year-by-year table, chart and inflation adjustment.