How Averaging Down Changes Your Cost Basis
Calculate a new weighted cost basis after an additional stock or crypto purchase and understand the concentration risk.
The concept in plain English
An average-down calculator combines an existing position with a proposed new purchase to show the resulting weighted average price. It also reveals the additional capital and total exposure required to lower the cost basis.
Open Stock/Crypto Average-Down CalculatorA lower average is not a smaller exposure
Averaging down can improve the price needed to break even while increasing the money exposed to the same asset. Evaluate the proposed purchase on its own merits: would you buy it without the existing holding? Review the position's share of the portfolio and the downside if the original thesis is wrong. Keep this decision separate from scheduled dollar-cost averaging, which does not depend on a prior loss.
A lower average with more capital at risk
An existing 10 units at $100 and a proposed purchase of 10 more at $80. Fees are excluded.
Total cost = 10 × $100 + 10 × $80 = $1,800. Total units = 20. Average = $1,800 ÷ 20 = $90.
The average falls from $100 to $90, while invested capital rises from $1,000 to $1,800.
At an $80 market price, the combined holding is worth $1,600 and still has a $200 unrealized loss.
Calculation method
New average price equals existing cost plus new purchase cost, divided by total existing and added units. The calculation weights each price by the units purchased.
| Input | Purpose |
|---|---|
| Existing units | Current position quantity. |
| Existing average | Current weighted cost per unit. |
| New purchase price | Expected price of the added lot. |
| Cash or units added | Defines the size of the proposed purchase. |
Step-by-step workflow
- Enter current units and their average cost.
- Add the proposed purchase price and either cash amount or units.
- Review the new average, total exposure and added concentration before deciding.
Practical benefits
- Calculates a true weighted cost basis.
- Shows how much capital a target average requires.
- Makes total position growth visible.
Questions about Stock/Crypto Average-Down Calculator
Does averaging down reduce my loss?
It lowers the average entry but increases capital exposed. The position can still lose more money if price continues to fall.
Why is a simple average of prices wrong?
A simple average ignores purchase size. Weighted cost basis gives larger lots proportionally more influence.
Can I enter cash instead of units?
Yes. The calculator can convert a proposed cash amount into units at the new purchase price before combining the lots.
Examples are hypothetical and exclude costs unless stated. This is educational material, not individualized investment or tax advice. Read our methodology and risk disclosure.