Online Tool Store
Position Size Calculator
Calculate shares, risk dollars, risk per share, and position value from account balance, risk percentage, entry price, and stop-loss distance.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
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Example shown — enter your own numbers.
- $ at risk
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- Risk per share
- Position value
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How it works
- Enter your account balance and how much of it you're willing to risk on this trade, as a percentage.
- Enter your planned entry price and stop-loss price.
- See exactly how many shares/units to buy to keep your risk at that percentage.
The formula
$ at risk = Account balance × (Risk % ÷ 100)
Risk per share = |Entry price − Stop-loss price|
Position size = $ at risk ÷ Risk per share
Example: a $10,000 account risking 1% ($100) on a $50 entry with a $48 stop gives a $2 risk per share, so 100 ÷ 2 = 50 shares.
FAQ
What risk percentage should I use per trade?
Many traders use 1-2% of account balance per trade as a common risk-management guideline, so a string of losses doesn't wipe out the account — but the right number depends on your own strategy and risk tolerance, not a fixed rule.
Why does the position size depend on my stop-loss, not just my entry price?
The dollar amount you're willing to lose (your risk) is fixed by your account and risk %; how many shares that buys you depends on how far your stop is from your entry — a tighter stop lets you size a larger position for the same dollar risk, and vice versa.
Does this work for shorting as well as buying?
Yes — the math only cares about the distance between entry and stop-loss, not which direction the stop is on. Enter your stop-loss price above or below your entry to match your position's direction, and the risk-per-share calculation works either way.
Is my trading data sent anywhere?
No — every figure stays in your browser. The calculation is plain arithmetic run locally.
How we compare
| Feature | Online Tool Store | Broker's built-in calculator | Spreadsheet formula |
|---|---|---|---|
| No login or brokerage account needed | ✓ | Account required | ✓ |
| Works for any market, not just one broker's | ✓ | Tied to that broker's assets | ✓ |
| No ads | ✓ | ✓ | ✓ |
A quick, broker-agnostic sizing check before placing a trade, without opening a spreadsheet or being locked into one platform's tool.