Stock Average Calculator

How to read the two numbers

The first is what the position cost you per share. Not the average of the prices you typed — the total money that left your account, commission on every buy included, divided by the shares you hold. On this page's defaults — 100 shares at 50.00, then 150 at 40.00, then 100 at 32.00, with 4.95 charged on each order — the market got 14,200.00, the broker took 14.85, and 350 shares cost 14,214.85, which is 40.6139 a share. The plain average of the three prices, weighted by shares, is 40.5714; the 0.0425 gap is the commission.

The second is the price you have to sell at to be square. Selling triggers the commission again, so the break-even has to sit above the average by that charge spread over your shares: 40.6280 here, which is 0.0141 above the 40.6139 average. That gap is small on 350 shares and it is not zero — and it is the whole reason the average on its own is not the number you want.

Everything on this page is arithmetic from the numbers you typed. No quote is fetched, no ticker is looked up, nothing is uploaded or saved — which is also its limit: it cannot tell you whether the prices you entered were ever available to you.

The arithmetic behind it

Every buy contributes its shares and its price, plus the commission that buy triggered. The average is then the money over the shares, not the mean of the prices — those are two different numbers whenever the buys are of different sizes:

Two things fall out of it. The average moves toward whichever price carried the most shares, so 150 shares at 40.00 pulls it further than 100 shares at 32.00 does, even though 32.00 is the lower price. And the reverse solve only has an answer when the buy price sits below the target — buying at 34.00 cannot land your average on 34.00, let alone below it. Where the arithmetic has no answer the page says so instead of printing a number.

Worked example you can check by hand

Three buys of the same stock, 4.95 charged on each order:

The bottom three rows are the point of putting the commission in at all: 14.85 on the way in and 4.95 on the way out is 19.80 the price difference alone would not have told you about.

What each buy did to the average

The same three buys, read one at a time — this is the part a single box with two prices cannot show you:

The second buy pulled the average down 6.01 and the third pulled it a further 3.43, less than the second did despite being the lower price, because it was the smaller number of shares. Every later buy moves the average and the break-even together, which is exactly what the adding to a position page is about from the risk side rather than the cost side.

Averaging down: what the next buy has to be

This is the question the name actually asks. You hold 350 shares at 40.6139 and the price is below you: how much do you have to buy, and at what price, to land the average where you want it? The box above solves it in one direction — give it the average you want and the price you would buy at, and it gives you back the share count. At a target of 38.00 and a buy price of 30.00 it answers 114.9750 shares for 3,454.20, which takes you to 464.975 shares at 38.0000 and drops the price you need from 40.6280 to 38.0106.

Pulling the average from 40.6139 to 40.00 costs 664.35. Pulling it to 34.00 costs 17,403.45 — twenty-six times as much for a further six dollars. The last row also doubles your position, which is the part the arithmetic cannot decide for you: averaging down buys a lower break-even by putting more money into the thing that has been falling.

The average falls by the same 2.6139 in every row, because that is what the target says. What changes is what you pay for it: the same two-dollar-sixty move costs 7,823.25 if you buy at 34.00 and 1,026.95 if you buy at 20.00. Waiting is cheaper per dollar of average; it is also a bet on getting filled.

Commission moves the price you need

The three buys stay the same. Only the charge changes, and it lands on the average and again on the break-even:

At zero commission the average and the break-even are the same number — which is why so many average calculators stop at the average. At 19.95 an order they are 0.0570 apart, and every one of those cents is money the price has to travel before you are square. On 350 shares that is 19.95; on 50 shares it would be the same 19.95 spread over a seventh of the position, which is where flat charges bite hardest.

How much price sits between you and square

The break-even is one number for the whole position. The distance to it is what is worth watching, and the last two columns are the ones that catch people out:

At 40.00 the position is 0.61 under the average and 219.80 short of square — close enough to feel fine, and still a loss once both commissions are paid. That band, roughly a dollar and a half wide here, is the only reason to work the break-even out instead of stopping at the average.

Average down calculator — the same page under the other name

Averaging down is buying more of something you already own after the price has fallen, to pull the average cost down with it. That is not a different calculation, it is this one: every row you add above is another buy, and the average moves toward whichever price carried the most shares. The word comes in three shapes — stock average down calculator, share average down calculator and plain average down calculator — and all three are answered here, by the same tool.

What the name asks for, though, is not the average you already have. It is the average you want and what it takes to get there, which is the Plan the next buy box: put in the average you are aiming at and the price you would buy at, and it hands back the share count and the money. Adding below your average pulls it down; adding above pushes it up; adding at the average leaves it where it was. Nothing on this page decides whether you should — it only prices the decision once you have made it.

Where this one stops

• One stock, up to ten buys. It is one ticker bought several times, not a portfolio. Different tickers want one run each.
• One commission rule. The same charge is applied to every buy and once more on the sale. Brokers that charge differently on the way out are approximated, not modelled — the box is a placeholder, put your own number in.
• No tax, no dividends, no splits, no currency. A split changes both the share count and the price and has to be entered by hand; whatever your jurisdiction takes on the disposal is not in the figure.
• No prices, no broker, no history. Nothing is fetched and nothing imported. Every number came from you.
• Fractional shares. The reverse solve prints 114.9750 shares because that is the arithmetic; whole shares only, 115 puts you at 37.9996 rather than 38.0000.
• No signal, and no view on averaging down itself. Adding to a loser lowers your break-even and raises your exposure by the same trade. This page prices that; it does not tell you to do it.

On the five web calculators we read for this word on 21 October 2026 — praveenmp.github.io, stock-screener.org, sharepredictions.com, tradingcalculator.app and stockaveragecalculator.com — every one worked the average out as the money divided by the shares with no commission anywhere in it, and none of the five had a way to ask what the next buy has to be. Two of them said your break-even is that average, which holds only when the round trip is free; one of those two tells you to add your broker's fees for a true net figure and then offers no box to put them in. Three of the five take more than two buys, so being able to enter several is the ticket to this word, not the reason to be here. The claim stops there: those five pages, that day.

The round trip from this average is the stock profit calculator, which charges both tickets and the tax on the gain. The same arithmetic on coins is the crypto profit calculator, and buying on a schedule rather than after a fall is the DCA calculator. What none of them decide is how much to put in — that is the stock position size calculator.

Questions people ask

It works out what one stock cost you per share when you bought it several times at different prices. On this page's defaults - 100 shares at 50.00, 150 at 40.00, 100 at 32.00, 4.95 commission on each order - that is 14,214.85 across 350 shares, or 40.6139 a share, with the commission in.

Multiply each buy's shares by the price it was bought at, add those up, add the commission each buy triggered, then divide by the total shares. Here: 14,200.00 to the market plus 14.85 of commission, over 350 shares, gives 40.6139. Dividing 14,200.00 by 350 gives 40.5714 instead, which is the average price rather than the average cost.

Yes, the same page under the other name. Averaging down is buying more after the price has fallen, which is what every extra row above is. The Plan the next buy box answers the question the name actually asks: give it the average you want and the price you would buy at, and on the defaults it answers 114.9750 shares at 30.00 for 3,454.20, landing the average on 38.0000.

No. Share and stock are the same instrument here, and the arithmetic does not care which word you searched. Whether you call it a stock average calculator, a share average down calculator or an average down calculator, it is the money divided by the shares, with the commission in, and the price that clears it on the way out.

Because the average covers what you paid to buy the shares, and selling triggers the commission again. On the defaults the average is 40.6139 and the break-even is 40.6280 - 0.0141 apart, which is the 4.95 charge on the sale spread over 350 shares. Set the commission to zero and the two numbers become the same.

Put the target and the price you would buy at into the Plan the next buy box. It solves for the share count, and it only has an answer when the buy price sits below the target - buying at 38.00 cannot land your average on 38.00. On the defaults, aiming at 38.00 and buying at 30.00 needs 114.9750 shares; aiming at 34.00 needs 579.95, more than doubling the position.

Yes, and by more as the position gets smaller. On the defaults 14.85 of commission across three buys moves the average from 40.5714 to 40.6139. That is 0.0425 a share on 350 shares; the same 14.85 on 35 shares would move it ten times as far.

No, and there is nothing to connect to. No quote is fetched, no API is called, nothing is uploaded or saved. Every figure is arithmetic from the rows you typed, in your browser.

For crypto, yes - pick percent of the value, since venues quote a rate on what you trade, and the arithmetic goes through unchanged. For forex it is the wrong shape: that market is priced in lots and spread rather than in shares and a per-order charge, so use the forex pages instead.

Related guides

• Adding to a position — several entries against one risk budget, which is the decision before the averaging.
• Stock profit calculator — the round trip from this average, both tickets and the tax on the gain.
• Crypto profit calculator — the same averaging with a fee on the value instead of a per-order charge.
• DCA calculator — buying on a schedule rather than after a fall.
• Stock position size calculator — how many shares a risk budget buys, before any of this.
• Profit factor calculator — what a journal of these trades adds up to.
• Forex, stock and crypto position size calculator