About the Stock Average Cost Calculator
When you buy the same stock or fund at different prices, your break-even point is the weighted average cost, not the simple average of prices. Enter each purchase's shares and price to see total shares, total cost and your average cost per share. Add the current price to see your unrealised gain or loss in money and percent — useful when dollar-cost averaging.
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The Curator field notes
A closer look at Stock Average Cost Calculator
FIELD NOTE 1
Include fees in the price per share for a truer cost basis.
FIELD NOTE 2
Fractional shares are supported — enter decimals.
FIELD NOTE 3
Your broker's tax cost basis may use FIFO or specific lots instead of averages.
FIELD NOTE 4
Averaging down lowers your cost but increases exposure to a single holding.
From input to result
- 1
Enter shares and price for each purchase.
- 2
Add more purchases as needed.
- 3
Optionally enter today's price to see gain or loss.
Category reference · illustrative chart
Compounding: time changes the comparison
Illustration only: 1,000 units growing at a fixed 5% per year, compounded annually, with no contributions, taxes, inflation or fees. Values use 1,000 × 1.05^years; this is not a forecast or an output of this calculator.
0 years · 1,000 currency units
5 years · 1,276.28 currency units
10 years · 1,628.89 currency units
20 years · 2,653.3 currency units
About money & business tools
Financial calculators are only useful if you understand the formula behind them. Each calculator on this page shows its working: the inputs it uses, the standard formula it applies, and what the result does and does not include. A mortgage figure that ignores property tax, or an ROI that ignores time, can be technically correct and still misleading.
These calculators are educational. They use widely published formulas — the same ones in finance textbooks and bank disclosures — but they cannot know your local taxes, fees or lender terms. Use them to understand the shape of a decision and to compare options, then confirm the final numbers with the institution or a qualified adviser. Nothing you enter is saved or sent anywhere.
Two habits make any calculator more useful. First, change one input at a time and watch how the result moves — that shows you which assumption actually drives the decision, whether it is the interest rate, the term or the price. Second, run a pessimistic and an optimistic scenario rather than a single 'expected' one; real rates, returns and costs rarely stay fixed for years. All figures are shown in whatever currency you are using, because the formulas are the same in dollars, euros or Icelandic krónur. Rounding is applied only for display, so the underlying maths stays precise.
Popular ways people use money & business tools
- Comparing a 15-year and a 30-year mortgage to see the real difference in total interest paid.
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Every tool in this collection is built and tested by The Curator team. Before a tool is published we check it against known reference results — textbook loan schedules, standard test vectors for hashes, sample files for conversions — and we re-check it whenever browsers change. Each page explains the method so you can verify the answer yourself rather than take it on trust.
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Frequently asked questions
- How is the average calculated?
- Total amount spent divided by total shares — a share-weighted average.
- Does it handle sales?
- No — enter only purchases still held.
- Is my input stored or sent anywhere?
- No. Everything runs inside your browser tab and disappears when you close it.
- Is the Stock Average Cost Calculator really free?
- Yes. There is no account, no trial and no watermark. The Curator is supported by advertising on its guide pages, never by charging for tools or selling your data.
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