Average Cost Basis Calculator
Average cost basis is the average price paid for each share you hold, when shares were bought at different prices. It is the starting point for working out a gain or loss.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
Add up everything paid for the shares, then divide by the total number of shares. That gives the average cost per share.
This calculator adds nothing else. If your records include commissions or fees as part of cost, add them to the total paid. Rules on how cost basis is figured can differ, so check your records or ask a tax professional.
Worked example
Having paid $12,000.00 for 300 shares, the average cost is $40.00 a share. At $48.00 a share, the holding is worth $14,400.00, a gain or loss of $2,400.00.
Questions
Do I include shares I have already sold?
No. Use only the shares still held. Sales are usually handled with a separate method, so keep this calculator to what you own.
What if I bought at different times?
That is the normal case. Add the total paid from every purchase and the shares from every purchase, then use those totals here.
Is a gain on paper the same as a tax bill?
No. It is the difference between cost and value. Any tax depends on how long the shares were held and on the rules where you live.
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