How to use the Stock Average Down Calculator
Estimate the weighted average stock purchase price after an additional share purchase.
Calculation formula
New average price = (existing shares × existing price + new shares × new price + new fees) ÷ combined shares.
Recommended steps
- Enter values using the units shown beside each field.
- Review whether the example assumptions match your situation.
- Run the calculator and compare the key metrics.
- Use the source data or official rates when precision matters.
Known limitations
This is a purchase cost-basis estimate, not a recommendation to buy more of a falling stock. Previous transaction fees should be included in the initial average if applicable.
Open the calculator →