How does the Cost Basis Calculator work?

Enter your values into the input fields, adjust any parameters, and click Calculate. The tool processes your input instantly and displays accurate results. All calculations happen locally in your browser for privacy and speed.

Is the Cost Basis Calculator free to use?

Yes, this tool is completely free with no signup required. Everything runs locally: Split Ratio and Current Price are processed on your device, never sent to a server — your data is never uploaded to any server, ensuring complete privacy and security.

Are the Cost Basis Calculator results accurate?

Yes, the calculator uses standard mathematical formulas and algorithms to ensure accurate results. Calculations are performed using JavaScript's built-in precision. For financial or medical decisions, always verify with a professional.

Free Online Cost Basis Calculator

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Free online Cost Basis Calculator for stock investments. Supports multiple purchases, dividend reinvestment, and stock split adjustments. Pure frontend computation. | No signup · Data never leaves your device

Zero dependencies · Works offline

Input Data

Purchase Lots (shares price per line)

Split Ratio

Current Price:

Results

Weighted Avg Cost

Adjusted Shares

Total Cost

Unrealized G/L

Formula Guide