Stock Average Price Calculator
Last updated: July 2026
Calculate the weighted average share price after an additional stock purchase.
New average share price
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- Total shares: —
- Total cost basis: —
- Change from prior average: —
On this page
Quick summary: Calculate the weighted average share price after an additional stock purchase. Enter your own values, calculate, and compare scenarios in US dollars.
Read the complete guide
What this calculator estimates
Calculate the weighted average share price after an additional stock purchase. The calculation runs locally in your browser and is intended for planning and comparison.
How to use it
Enter the requested values, select Calculate, review the headline result and supporting figures, then change one input at a time to compare another scenario.
How the calculation works
The new average price is total existing and new cost, including fees, divided by total shares.
Input checklist
The Stock Average Price Calculator uses the values shown in its form. Before calculating, check each input independently so an incorrect unit or time period does not carry through to the final result.
- Existing shares: verify that this value uses the unit, period, and definition shown by the calculator.
- Existing average price per share ($): verify that this value uses the unit, period, and definition shown by the calculator.
- New shares purchased: verify that this value uses the unit, period, and definition shown by the calculator.
- New purchase price per share ($): verify that this value uses the unit, period, and definition shown by the calculator.
- Trading fees ($): verify that this value uses the unit, period, and definition shown by the calculator.
Practical interpretation
Use the Stock Average Price Calculator result as the answer to the specific inputs entered, not as a universal value. The calculation currently described on this page is: The new average price is total existing and new cost, including fees, divided by total shares. Change one important input at a time when comparing scenarios so you can see which assumption actually drives the difference.
Checks before relying on the result
The result depends on the values and units entered. Recheck the inputs and compare the estimate with the real-world source or rule that applies to your situation. Recalculate when a key value changes, and keep the original inputs with the result if you need to reproduce or compare the calculation later.
Important limitations
Tax-lot identification, wash-sale adjustments, return of capital and corporate actions can affect tax basis.
Frequently asked questions
Is this result exact?
No. It is a planning estimate based on the values entered and the method described on the page.
Can I enter Arabic or Persian digits?
Yes. Arabic and Persian digits are normalized to English digits inside numeric fields.
Does the calculator store my inputs?
No. The calculation runs locally in your browser and does not require an account.