Cost Basis Calculator: New Purchase

Your new average cost per share after buying more, plus total invested and gain or loss at the current price.

Shares held

Cost basis per share ($)

New shares to buy

Purchase price per share ($)

Current market price ($)

Calculating…

New blended cost basis vs. the number of new shares purchased. The dashed line is your current basis; the marker shows your purchase.

Assumption check

For averaging into a stock you already hold. Enter the shares you are buying, not the dollars.

The Investor Stats Cheat Sheet

A free two-page PDF: expected value, Kelly sizing, Sharpe, sample-size math, and how to read a p-value without fooling yourself. Plus new tools as they ship.