What is the Cost Basis Calculator?
The Cost Basis Calculator is a free online tool that helps you adjusted cost basis across lots and splits It runs entirely in your browser, gives an instant result, and needs no sign-up, download or spreadsheet.
Your average cost is simply total money in divided by total shares held; it moves toward whatever price you trade most volume at, which is why adding at lower prices pulls it down.
Whether you trade stocks, forex, options, crypto or futures, the cost basis is the same calculation — so this tool works for any market. Use it before you place a trade to base your decision on real numbers instead of a guess.
How to use the Cost Basis Calculator
Using the cost basis calculator takes only a few seconds:
- Enter your figures in the cost basis calculator above — the fields are filled with an example you can replace.
- Read the highlighted result; it updates instantly as you type.
- Add your broker’s fees or commissions where relevant for a true net figure.
- Change any input to compare scenarios before you commit to the trade.
Cost Basis formula & example
The cost basis formula is: Cost basis = (shares × price) + fees.
When to use the Cost Basis Calculator
Reach for the cost basis calculator whenever you’re planning a trade and need to know your cost basis in advance. Running the number first keeps your decisions consistent and stops a single trade from doing outsized damage to your account. Traders who make this a habit — checking before every entry — are the ones who protect their capital over the long run.
Why use a cost basis calculator?
Doing cost basis by hand is slow and error-prone — a misplaced decimal or a forgotten fee can turn a winning plan into a losing one. The cost basis calculator removes that risk: it applies the correct formula every time, updates the moment you change an input, and lets you test several scenarios in seconds.
That speed matters in live markets. When a setup appears you can size it, check the reward against the risk, and act before the opportunity passes — without second-guessing your arithmetic.
- Instant, accurate cost basis with no spreadsheet
- Free, with no account, login or download
- Works on mobile and desktop, right in your browser
- Useful for stocks, forex, options, crypto and futures
Tips for accurate cost basis
- Use your real entry, exit and size — not round-number guesses.
- Include fees and spread; small costs add up across many trades.
- Recalculate whenever your price, size or stop changes.
- Round against yourself to leave a margin for slippage.