Stock Average Down Calculator
Averaging down is the most common trade in investing and the least often computed: you own 100 shares at $50, the stock drops to $35, and buying another 100 lands your break-even at $42.50 - not $35, and not the midpoint either. This calculator does that blend instantly, plus the totals that decide whether the add is wise: combined shares, combined capital in the position, and how much the average actually moved.
The honest number here is break-even. Averaging down does not un-buy your expensive shares - it re-weights them - so the note under the result states the new bar plainly and what it does and does not fix. Your inputs are remembered for scenario testing, results land in the tab title, and one tap shares the full position via a link that carries the numbers.
How to use
- Enter the shares you own and the average price you paid.
- Enter the size and price of the new buy.
- Read the blended average, total invested and the new break-even - tweak numbers to compare scenarios.
Frequently asked questions
How is the new average cost calculated?
Total dollars invested divided by total shares owned: (old shares × old price + new shares × new price) ÷ total shares. On 100 @ $50 plus 100 @ $35 that is $8,500 ÷ 200 = $42.50. The weighted blend is always between the two prices, closer to whichever buy was bigger.
Does averaging down lower my break-even?
It lowers it toward the new price, never to it. Each add pulls the average closer to that add's price in proportion to its size - which is why the calculator shows 'average lowered by' as a percentage: the move from $50 to $42.50 is real relief, but the shares bought at $50 are still underwater until the stock passes $42.50.
Is averaging down a good idea?
It is a bet that the thesis is intact and the drop is noise - the math is neutral, the judgment is yours. What the numbers do show is position sizing: the second buy raises your capital at risk to $8,500 in the example. Decide the total you are willing to own before the first buy, not after the drop.
Does it work for averaging up or crypto/forex?
Yes - the formula only cares about shares and prices, so averaging up into strength works identically, and units of any asset (coins, lots, ETFs) calculate the same. Fees are not modeled; add them mentally to the new buy's price if they are material.