Stock Average Purchase Price Calculator

Using the Stock Average Purchase Price Calculator

Enter one purchase per row as quantity,price,fees. Use the same security and currency for every row. Fractional quantities are accepted, so the tool also works for units acquired through fractional-share purchases when the underlying cost convention matches.

Worked example

Use the example inputs below to reproduce this result. These are the form's starting values, not recommended targets. Changing your inputs updates your result above; this worked example stays fixed for comparison. Results are rounded for display.

Method and assumptions

Purchase-only weighted average = sum(quantity × price + purchase fees) / total quantity. Fractional units are supported. Use one currency and the same security; do not mix sales, short positions, splits or currencies. Break-even excludes future selling fees and taxes. This is cost arithmetic, not an instruction to buy or sell.

Reference: investor.gov — method and further reading ↗

Separate contributions from growth

An ending balance can grow because you put more money in, because the assumed return is higher, or because the money has more time to compound. Those are different effects. Keep the contribution schedule consistent when comparing rates, and distinguish a mathematical projection from a return that is contractually guaranteed. Fees and taxes need their own assumptions.

Common question

Is average cost the sale price at which I make a profit?

It is the per-unit cost including entered purchase fees. Selling fees and taxes can raise the actual break-even sale price. The result is a purchase-cost summary and does not calculate realized gains or recommend a transaction.