Average Cost (Cost-Basis) Calculator

Working out your true cost basis

When you buy the same stock or coin more than once at different prices, your average cost — your cost basis — is what actually determines your profit or loss, not any single purchase price. This calculator blends every buy into one figure: total money spent divided by total units acquired.

Knowing your real average matters for clear thinking. It tells you the price at which you break even, and it stops you from anchoring to the price of your first or your most recent purchase. A word of caution on the name: "averaging down" — buying more as a price falls — lowers your average cost, but it also increases your exposure to an asset that is, by definition, losing value. A lower average is not the same as a good decision. Use the figure to understand your position, not to justify adding to a losing one.