Position Size Calculator
Free position size calculator: risk a set % of your account with a stop-loss and get an exact share count. Built for the 1% rule and risk management.
Turn account size, risk %, entry, and stop-loss into an exact share count. Built around the 1% rule so one bad trade can’t wipe out months of progress. Essential risk math before you click buy.
What is a position size calculator?
A position size calculator answers one question before every trade: how many shares can I buy without risking more than I planned? You input account size, risk percentage, entry, and stop-loss. The tool outputs a share count so a normal stop-out costs a fixed, small slice of capital — not an emotional “I’ll give it more room” loss.
The position size formula (1% rule)
Position size = (Account × Risk %) ÷ (Entry − Stop)
Example: $10,000 account, 1% risk = $100. Entry $50, stop $48 → $2 risk per share → 50 shares. If price hits the stop, you lose about $100. That’s the point — the loss is known before you click buy.
Pros often risk 0.5–2% per trade. Higher risk compounds drawdowns fast; lower risk keeps you in the game while you learn. Read our full guide: How to calculate position size.
How to use this free position size calculator
- Enter account equity (cash + positions you treat as trading capital).
- Set risk % — start at 1% if you’re unsure.
- Enter entry price and stop-loss (where your thesis is clearly wrong).
- Buy only the suggested share count (or fewer).
- Practice the habit in our stock market simulator before using real money.
Why position sizing beats “hot tips”
You can be right on direction and still blow up if size is wrong. Oversizing turns a normal pullback into a panic exit. Undersizing wastes edge. A free position size calculator makes risk a process: same rules every trade, easier journaling, and fewer “all-in” mistakes. Pair it with our investment return calculator to review whether your risked dollars are producing acceptable returns.
Common position sizing mistakes
- No stop defined: Without a stop, “risk %” is fiction — you’re gambling with undefined downside.
- Moving the stop farther: That silently increases risk after entry. Recalculate size instead.
- Risking % of buying power only: Size off total equity you’re willing to treat as the account, not leftover cash.
- Same share count every trade: Volatile stocks need fewer shares for the same dollar risk.
Frequently asked questions
Related free trading tools
Explore more free calculators and simulators on Swift Penguin: stock market simulator, live stock lookup, compound growth projector, dividend & DRIP calculator, options profit calculator, portfolio tracker, dollar cost averaging calculator, stock profit calculator, and investment return calculator. Browse all free stock trading tools.
Educational use only — not financial advice. Markets involve risk of loss. Always do your own research.
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