Simple investing clarity

Know your true average stock cost.

Calculate your average stock cost, then compare what two possible buys would change.

Compare two scenarios
1. Add purchasesEnter each purchase price and shares bought.
2. See average costInstantly see your average cost per share.
3. Compare possibilitiesSee the cost and cash needed for two possible buys.
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Stock average calculator

Add purchases of one security to calculate its weighted average purchase cost.

Purchase price ($)
Shares bought
Average cost per share
$0.00
Total invested
$0.00
Total shares
0
Current value
$0.00
Profit / loss
$0.00
0.00%

Results update automatically. Use purchases of one security in one currency only. Fully blank rows are ignored; partially filled rows need completion.

Current position

Sell calculator (optional)

Uses your weighted average purchase cost, not FIFO or specific tax lots. It does not record a transaction. See a worked sale example.

One position. Two possibilities.

Compare two possible buys

Use the purchases above as your starting position. Compare the extra cash, shares and average cost for two separate scenarios.

Plan A

Plan B

Add your starting purchases above, or try the fictional comparison example.

No additional buy

Average cost per share

—
Additional cash
—
Total invested
—
Total shares
—
Shares added
—
Change in average
—
Value at entered current price
—
P/L at entered current price
—

Plan A

Average cost per share

—
Additional cash
—
Total invested
—
Total shares
—
Shares added
—
Change in average
—
Value at entered current price
—
P/L at entered current price
—

Plan B

Average cost per share

—
Additional cash
—
Total invested
—
Total shares
—
Shares added
—
Change in average
—
Value at entered current price
—
P/L at entered current price
—

Read the cash commitment alongside the average. A lower average alone does not mean a profit. In the comparison example, new shares are added at the entered current price: the average falls, while the dollar loss stays the same.

Both plans use the original purchases above. The optional simulated sale is separate. Enter a current share price to compare value and P/L at that same price.

Assumes fractional shares and no commissions, taxes, dividends or currency conversion. Values are rounded for display; calculations retain full precision. All prices are your assumptions, not forecasts.

Shares the purchases, current price, sale estimate and both comparison plans entered on this page.

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The simple guide

What is dollar cost averaging?

Dollar-cost averaging means investing equal amounts at regular intervals, regardless of market movements. This calculator does not create an investing schedule or forecast returns. It combines the actual purchase prices and share quantities you enter to show your weighted average purchase cost.

Knowing your average stock price helps you understand when your investment reaches breakeven and how strongly price changes affect your portfolio. It is especially useful for long-term investors who add to positions during market pullbacks, recurring investment plans, or periods of uncertainty.

Average cost = Total invested ÷ Total shares

To use the calculator, enter the price and number of shares for each purchase. Add as many rows as needed, then optionally enter the current share price to see your market value, dollar profit or loss, and percentage return. You can also enter a sale to estimate remaining shares and average-cost estimated gain or loss. Results are estimates and do not account for commissions, taxes, dividends, or currency conversion.

Check the calculation with a worked example

Buy 2.5 shares at $100, 5 at $80 and 1.25 at $120. Total purchase cost is $800 for 8.75 shares, giving a $91.43 weighted average. At an entered price of $100, market value is $875 and unrealized gain is $75 before costs.

Load these sample purchases · Follow every calculation step

Guides and explainers

Build a clearer understanding of cost basis, recurring investing, and risk.

Frequently asked questions

What is dollar cost averaging?

Dollar-cost averaging means investing equal amounts at regular intervals, regardless of market price. It does not guarantee a profit or protect against losses.

How do I calculate my average stock price?

Multiply each purchase price by its share quantity, add the purchase amounts together, and divide the total investment by the total number of shares.

What is the difference between average price and cost basis?

Average price is your cost per share. Here, total purchase cost is the sum of entered price × shares. Tax cost basis can require fees, adjustments and specific purchase lots; this tool does not calculate those.

Does this calculator include trading fees?

No. It does not automatically include commissions, taxes, dividends, or currency conversion costs. Include applicable fees in your own purchase records for a more complete estimate.

Can I use this calculator for fractional shares?

Yes. Enter fractional quantities such as 0.25, 1.5, or 3.75 in the shares field.

Is my investment data stored anywhere?

Calculations run locally without Google advertising. New share links encode inputs after # in the URL; this is not encryption. The page reads and removes that data from the address bar. Older ?data= links may expose values to hosting logs. Anyone with either kind of link can read the values, so only share with people you trust.

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