Stock Average Calculator

Work out your new average share price after buying more (average down or up), including brokerage and fees — instantly and privately in your browser.

Your current position

New here? Leave both at 0 — this just becomes a fresh-buy average.

Buys

Currency

Fees

New average cost per share —
New total shares
—
Simple average (excl. fees)
—
Invested this session
—
Total cost (incl. existing)
—
Fees this session
—
Break-even price
—

Estimate only — fees vary by broker and change over time. Edit the fields to match your contract note. This is not financial or tax advice.

How to use

  1. Enter the shares you already hold and your current average price (leave both at 0 if this is a brand-new position).
  2. Add each buy as a row — quantity and price per share. Pick a market preset to fill in typical brokerage and fees, then tweak any field to match your contract note.
  3. Press Calculate to see your new average cost per share, total shares, fees and break-even. Set a “home currency” to also see the result converted.

FAQ

How is the new average price calculated?

It is a weighted average of everything you own. The calculator adds the cost of your existing shares (shares held × current average) to the cost of every new buy, then divides that total cost by the new total number of shares. Buying more below your current average pulls the average down (averaging down); buying above it pulls the average up.

Do brokerage and fees change my average?

Yes. Your real cost per share is what you actually paid, fees included, so this tool adds brokerage, exchange and clearing fees, stamp duty and any tax on fees to each buy. The headline “new average cost per share” includes those costs; the “simple average” line shows the price-only figure so you can compare the two. Your break-even price equals your average cost.

Is anything I type sent to a server?

No. All the maths happens in your browser, so your share quantities, prices and fees are never uploaded. The only optional network request fetches public exchange rates for the home-currency conversion, and it sends none of your numbers. Figures are estimates and this is not financial or tax advice.