Stock Average Calculator
Combine two stock purchases into one average cost per share. See your total shares, total invested and the new breakeven price after averaging down or up.
Reviewed by the CalcCafe editorial team · Last updated 18 July 2026 · How we test our tools
Example
You buy 100 shares at $50, the stock falls, and you buy another 150 shares at $30. Your total investment is 100 × $50 + 150 × $30 = $9,500 across 250 shares, so your new average price is 9,500 ÷ 250 = $38 per share. The stock now only has to climb back to $38 — not $50 — for you to break even.
How it works
Average price = (q₁ × p₁ + q₂ × p₂) ÷ (q₁ + q₂), where q is the number of shares and p the price paid in each buy. Total shares is simply q₁ + q₂, and total invested is the sum of both purchase amounts. The same weighted-average formula extends to any number of lots — run the tool again using your current average as the first buy to add a third purchase.
Good to know
Averaging down means buying more of a stock after its price falls, which lowers your average cost per share and your breakeven point. It only helps if the stock eventually recovers: adding money to a falling position increases both your share count and your exposure, so a further decline loses you more than the original stake would have. Traders call buying into a steep, ongoing decline catching a falling knife — before averaging down, ask whether you would buy this stock today if you owned none, at this price, on its current fundamentals.
Averaging up — adding shares after the price has risen — raises your average cost but can be rational when a company keeps confirming your thesis with growing earnings or market share. Many systematic investors prefer it because it concentrates money in positions that are working rather than ones that are failing. The trade-off is a higher breakeven: after averaging up, a smaller pullback puts the whole position underwater, so many investors add in progressively smaller lots as the price climbs.
Your average cost also matters at tax time. In the United States, brokers report cost basis to the IRS, and when you sell part of a position you can generally choose a lot-selection method: FIFO (first in, first out) is the default for stocks, while specific-share identification lets you sell the exact lot that produces the smallest gain or a useful loss. Mutual funds may also use the average-cost method. The blended figure this calculator produces is your economic breakeven; the lots themselves remain separate for tax purposes unless you elect averaging.
Position sizing is the discipline that makes averaging survivable. A common approach is to cap any single stock at a fixed percentage of your portfolio and to plan the full position before the first buy — for example, three tranches of one-third each at pre-set prices — rather than improvising after a drop. That converts averaging down from an emotional rescue into a planned accumulation, and it stops one losing name from swallowing money that was meant for diversification.
Frequently asked questions
How do I calculate my average stock price after buying twice?
Multiply the shares by the price for each purchase, add the two amounts together, then divide by the total number of shares. This calculator does it instantly: enter the quantity and price for each buy and it returns the weighted average cost per share.
Does averaging down always lower my breakeven price?
Yes — any purchase below your current average pulls the average down, and the more shares you add relative to your existing position, the closer the new average moves to the latest price. Your breakeven falls, but your total money at risk rises.
Is my portfolio data uploaded anywhere?
No — this calculator runs entirely in your browser. The share counts and prices you enter never leave your device, and the tool works offline once the page has loaded.
Is this stock average calculator free?
Yes, completely free with no sign-up, no limits and no ads blocking the result. Use it as often as you like for any number of scenarios.
People also ask
What is the formula for average stock price?
Average price = (shares₁ × price₁ + shares₂ × price₂) ÷ (shares₁ + shares₂). It is a weighted average, so a larger second purchase pulls the average further toward the second price than a small one would.
Should I average down on a losing stock?
Only if you would still buy the stock today on its fundamentals. Averaging down lowers your breakeven but increases your total exposure, so it magnifies losses if the decline continues. Never average down just to repair a losing trade emotionally.
How does average cost affect taxes when I sell?
For US stocks each lot keeps its own cost basis; FIFO is the default sale order, but specific-share identification lets you pick which lot to sell and control the taxable gain. The blended average is your economic breakeven, not automatically your tax basis per share.
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Sources & references
These tools follow our methodology and provide educational estimates only — verify important figures with a qualified professional.