# Stock Average Cost Calculator

> Stock average cost calculator: compute weighted average share price, total shares, cost basis, and unrealized gain from your buys. Free, private, no signup.

- **Canonical URL:** https://boringtoolskit.com/stock-average-cost-calculator/
- **Category:** Finance & Investing
- **Evidence level:** authored-methodology
- **Reviewed:** July 26, 2026
- **Last verified:** 2026-10-12
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

## How it works

Average cost = (shares1 x price1 + shares2 x price2) / total shares.

## Common questions

### What is a stock average calculator and how does it work?

A stock average calculator helps you compute the average cost per share of a stock you have purchased multiple times at different prices. You simply enter each buy transaction's share count and price, and the tool instantly calculates your weighted average cost basis.

### Do I need to create an account or sign up to use this tool?

No. This is a fully no-signup, browser-based tool. All calculations are performed locally on your device, your data never leaves your browser and is never stored on any server.

### Is the stock average calculator free and accurate?

Yes, the tool is completely free to use and calculates your average cost using a precise weighted-average formula based on the number of shares and purchase prices you enter. It is designed to be a reliable reference for personal investment tracking.

## Sources

- [Calculation methodology](/methodology/)
- [Quality evidence and verification standard](/quality-evidence/)

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