Decision tool
DCA / average-cost calculator
Combine multiple entered purchases into one weighted average purchase price without treating the result as tax basis or strategy performance.
Calculator
Combine entered purchase lots
Enter every purchase in the same quantity unit and currency. No market data is fetched or transmitted.
Method
Formula and logic
Multiply each purchase quantity by its price, add those entered purchase amounts, then divide by total quantity. This is a weighted average, so larger purchase quantities affect the result more than smaller ones.
Verification
Worked example
Buying 10 units at 100 and 20 units at 70 produces total quantity 30 and entered purchase amount 2,400. The weighted average entered purchase price is 80 per unit before fees.
Boundaries
Limitations
- The result is an entered weighted average, not a tax calculation or performance measure.
- Every row must refer to the same asset, quantity unit, and currency.
- Fees, taxes, sales, transfers, dividends, splits, and other corporate actions are excluded.
Questions
Frequently asked questions
- Why is this not my tax cost basis?
- Tax basis can depend on fees, sales, lot selection, transfers, wash-sale rules, corporate actions, and jurisdiction-specific treatment that this calculator does not model.
- Does a lower average prove DCA worked?
- No. The average describes entered purchases only. It does not compare them with current value, alternatives, risk, or future performance.