Stock Average Calculator

1. Enter your buy prices, one per purchase, separated by commas.
2. Enter the shares bought in each purchase, in the same order.
3. Read your average price, total shares and total invested.
4. Add another buy to see how it moves your average.

Here is what each result means:

Stock averaging means buying the same stock at different prices and working out a single average cost per share. Your average price is the total money invested divided by the total shares, and it is the price the stock must pass for your whole position to break even, before fees and taxes.

It matters because it is easy to lose track after several buys. Knowing your true average, rather than the price of your first or last purchase, tells you where you actually stand and what a sale would realise.

It is a weighted average: each buy price is weighted by how many shares you bought at it, so a large purchase counts for more than a small one.

1. Multiply each buy price by the shares bought at it.
2. Add those amounts for your total cost.
3. Divide the total cost by the total shares for the average price.

Suppose you buy 10 shares at 100, 10 at 90 and 20 at 80.

Calculation: total cost = (10x100) + (10x90) + (20x80) = 1,000 + 900 + 1,600 = 3,500. Total shares = 40. Average = 3,500 / 40 = 87.50.

Even though your first buy was at 100, your average is 87.50 because the larger, cheaper purchase pulls it down. The stock only needs to reach 87.50 for the position to break even.

Buying more shares after the price moves changes your average in a predictable direction.

Averaging down lowers your break-even but increases your exposure to a stock that is already falling, which can be risky if the decline reflects a real problem. Averaging up is common when adding to a winner. Neither is automatically good; both depend on your view of the stock.

The Size of Each Buy

Bigger purchases pull the average toward their price. A large cheap buy can move your average far more than a small expensive one.

How Far the Price Has Moved

Buying well below or above your current average shifts it more than buying near it.

Fees and Taxes

Brokerage fees and taxes raise your real cost per share. This calculator shows the pre-fee average, so add costs for your true break-even.

After Multiple Buys

Find your true average once you have bought a stock several times at different prices.

Planning a Break-even

See the price the stock must reach for your whole position to break even before you decide to hold or sell.

Weighing Another Purchase

Test how a new buy would change your average before you place it. Compare the potential gain with the ROI calculator.

1. Using a Simple Average of Prices

Averaging the prices alone ignores how many shares you bought at each. The correct method weights by shares.

2. Forgetting Fees

Brokerage and taxes raise your real cost. The break-even price is a little above the pre-fee average.

3. Misaligning Prices and Quantities

The first price must match the first quantity, and so on. A mismatched order gives a wrong average.

4. Confusing Average with Your First Buy

Your break-even is the average, not the price you first paid.

5. Averaging Down Blindly

A lower average does not fix a bad investment. Consider why the price fell before buying more.

The math is exact for the buys you enter, but it is a cost calculation, not investment advice.

Multiply each buy price by the shares bought at it, add those amounts for your total cost, then divide by your total shares. Buying 10 at 100, 10 at 90 and 20 at 80 gives 3,500 / 40 = 87.50 per share.

Averaging down means buying more shares below your current average, which lowers your average cost. It reduces your break-even price but increases your position in a stock that has already fallen.

No, this tool shows the average cost before fees. Brokerage commissions and taxes raise your real cost per share, so add them to find your true break-even.

Before fees, yes. The average price is the level the stock must reach for your whole position to be worth what you paid. Add fees and any taxes for the exact break-even.

A buy below your current average lowers it, and a buy above raises it, with larger purchases having a bigger effect. Enter the new buy above to see the exact new average.

A simple average of prices ignores how many shares you bought at each price. The weighted average counts a large purchase more than a small one, which is the correct method.

Yes. Enter every buy, including those above your average. Buying at a higher price raises your average, which the calculator shows automatically.

No. It calculates your average from the buys you enter. Splits, bonus shares and reinvested dividends change your share count and cost basis and would need to be entered as adjusted figures.

No. The calculation runs entirely in your browser and nothing you enter is stored or sent anywhere unless you choose to Save a result, which stays only in this browser.

• Cost basis and average cost (US SEC Investor.gov).
• Weighted average explained (Corporate Finance Institute).
• Dollar-cost averaging basics (US SEC Investor.gov).