How do I calculate average stock cost?

Average cost = Total amount invested ÷ Total shares purchased. Buying 100 shares at $50 and 50 shares at $60 = $8,000 total ÷ 150 shares = $53.33 average cost per share.

Average Cost Basis Calculator

Estimate average cost basis after buying shares at different prices.

This tool runs in your browser. None of your data is saved or sold.

Shares purchased (lot 1)

Price per share - lot 1 ($)

Shares purchased (lot 2)

Price per share - lot 2 ($)

Current share price ($)

Target sell price ($)

About This Calculator

When you buy shares of the same stock at different prices, your average cost basis determines your profit or loss for tax purposes. This calculator handles two purchase lots and a current price to show your blended cost, total position, and unrealized gain or loss.

Estimates only — not financial, tax, legal, or investment advice. Verify important results with a qualified professional before making decisions.

avg cost = (Shares₁×Price₁ + Shares₂×Price₂) ÷ (Shares₁+Shares₂); unrealized P&L = (current − avg cost) × total shares