BYTETOOLS

Stock Average Calculator

Calculate your weighted average cost per share across multiple buy lots, the break-even price after brokerage, and profit or loss at any price you enter.

Your buy lots

150
Total shares
$2,710.00
Total invested
$18.0667
Average cost / share
$18.0848
Break-even price

Position at a price you choose

$2,550.00
Position value
-$160.00
Unrealised loss
-5.90%
Return on cost

Averaging-down planner

A target of $17.00 is not reachable by buying at $17.00. To lower your average of $18.07, the target has to sit between the price you can buy at and your current average.

Average cost is total money invested (including buying fees) divided by total shares, so bigger lots carry more weight. No prices are fetched — every figure is one you typed, and nothing is uploaded. For your own records, not investment advice.

What is the Stock Average Calculator?

The ByteTools Stock Average Calculator works out the true average price you paid for a holding built up over several purchases.

  • Unlimited buy lots with per-lot quantity, price and fees
  • Weighted average cost, not a misleading simple average
  • Break-even price including buying and estimated selling costs
  • Unrealised profit or loss in currency and percent at any price
  • Averaging-down planner: shares needed to reach a target average
  • No live quotes or network calls; everything stays in your browser

How to use the Stock Average Calculator

  1. 1

    Add a row for each purchase with the number of shares and the price paid.

  2. 2

    Enter any brokerage or fees for each lot.

  3. 3

    Read the total shares, total invested and weighted average cost per share.

  4. 4

    Check the break-even price that covers your fees.

  5. 5

    Type a current price to see unrealised profit or loss, or a target average to plan a top-up.

About the Stock Average Calculator

The ByteTools Stock Average Calculator works out the true average price you paid for a holding built up over several purchases. Add one row per buy lot with the quantity and price, and the weighted average is the total money invested divided by the total shares — not the simple average of the prices, which is only correct when every lot is the same size.

Brokerage and fees are handled per lot and folded into the break-even price, so you can see the price the stock has to reach before you are genuinely square rather than just back to your entry. Type a current or target price and the tool shows unrealised profit or loss in both currency and percent terms.

There is a averaging-down planner too: tell it a price and it shows how many extra shares you would need to pull your average down to a target. Every price is typed in by you — the tool never quotes a market or connects to the internet, and all figures stay in your browser. Estimates for your own records, not investment advice.

Frequently asked questions

How do you calculate the average cost per share?

Divide the total amount invested by the total number of shares. If you bought 100 shares at $20 and 50 at $14, that is $2,000 + $700 = $2,700 across 150 shares, giving a weighted average of $18.00 — not $17, which is what averaging the two prices would wrongly give.

Why is my average different from the simple average of prices?

Because bigger lots carry more weight. A simple average treats a 10-share purchase and a 1,000-share purchase as equally important, which they clearly are not. Weighting by quantity is the only method that matches the money you actually spent.

What is the break-even price for a stock?

The price at which selling would return exactly what you put in, including buying fees and the fees you will pay on the way out. It is always slightly above your average cost, and this calculator shows the gap so it does not catch you out.

Should I average down on a falling stock?

Averaging down lowers your average cost but also increases your exposure to a position that is already losing money, so it only makes sense if your original reason for buying still holds. This tool shows the arithmetic of how many shares it would take; the judgement is yours.

Does this calculator fetch live share prices?

No. Every price is one you type in, and the tool makes no network requests at all. Copy the current price from your broker if you want a live profit or loss figure.

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