Calculate your average cost per share across multiple buy transactions, see live P&L, and plan averaging-down purchases. Supports USD, INR & AED.
A free Stock Average Calculator that handles unlimited buy transactions, computes your weighted average cost per share, current market value, and total profit/loss in real time. The unique averaging-down planner tells you exactly how many shares you need to buy at the current price to bring your average down to a target level — no spreadsheets, no formulas. A bar-and-line chart visualizes how each buy moves your running average so you can see the dollar-cost averaging effect at a glance. Works for stocks, ETFs, crypto, and any unit-priced asset across USD, INR, and AED.
The weighted average cost per share is the total amount invested divided by the total shares held. If you buy 50 shares at $180, 30 at $150, and 40 at $120, your total invested is $9,000 + $4,500 + $4,800 = $18,300 across 120 shares — an average of $152.50 per share. Each new purchase shifts this average toward the new buy price, weighted by how many shares you bought relative to your existing position. This single number is the most important figure for any stock position because it represents your breakeven point.
To compute how many additional shares you need to buy at the current price to reach a target average, the calculator solves a single equation: (existing invested + x × current price) / (existing shares + x) = target average. Rearranging gives x = (target × existing shares − existing invested) / (current price − target). The tool also detects unsolvable cases — for example, you cannot lower your average by buying at a price higher than your target.
The chart layers three pieces of information per buy: a bar showing how many shares you purchased, a green dot marking the price you paid, and an amber line tracing your running average across all buys to date. When the green dot is below the amber line, that buy pulled your average down; when it is above, the buy pushed your average up. Watching the amber line bend toward each new green dot teaches you exactly how DCA works in practice.
Dollar-cost averaging means investing fixed amounts at regular intervals regardless of price, smoothing your entry across market cycles. A lump-sum investment puts all capital in at once. Historically lump-sum beats DCA roughly two-thirds of the time because markets trend upward, but DCA reduces emotional risk and is the only practical approach when you earn money over time.
Averaging down makes sense when the price drop is driven by market-wide volatility rather than a deterioration in the underlying business — your original investment thesis must still be valid. It is a bad idea when you are throwing good money after bad in a stock that is structurally broken (falling earnings, accounting issues, sector decline) or when adding shares would over-concentrate your portfolio.
Your breakeven price is identical to your average cost per share — once the stock trades above that level you are in profit (before taxes and fees). This calculator shows breakeven as the headline "Average Cost / Share" figure. Add brokerage commissions and any applicable taxes by treating them as additional cost when entering each buy.
Most tax authorities (US IRS, Indian Income Tax, UK HMRC) let you choose between FIFO, LIFO, or specific-lot identification when computing capital gains. Your average cost basis is useful for ETFs and mutual funds, but for individual stocks specific-lot ID usually saves the most tax — sell the highest-cost lots first to minimize gains. Consult a tax professional for your jurisdiction.
The core average is based on shares × price per buy. To include brokerage fees, add them to the price per share for each transaction. Dividends received are not factored in here — they reduce your effective cost basis but are typically tracked separately. For dividend reinvestment modeling, use our Dividend Yield Calculator. Capital gains tax is computed at sale, not on the average.
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