Position Size Calculator
Free position size calculator: risk a set % of your account with a stop-loss, get share count and reward:risk. 1% rule presets. No signup.
Turn account size, risk %, entry, and stop into an exact share count — with 1% rule presets, optional target for R:R, and a live formula walkthrough. Size the loss before you click buy.
Size the risk first — then place the trade.
Formula: shares = (account × risk%) ÷ |entry − stop|. Inputs save in your browser.
Suggested size
50
shares
Bar scaled so 10% account risk = full width (1% ≈ a tenth of the bar).
- Dollar risk (planned)
- $100.00
- Loss if stopped
- −$100.00
- Risk / share
- $2.00
- Stop distance
- 4%
- Position value
- $2,500.00
- % of account
- 25%
- Reward if target hit
- +$300.00
- Reward : risk
- 3 : 1
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. Add an optional target and you’ll also see reward:risk (R:R) before you click buy.
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 enter.
Pros often risk 0.5–2% per trade. Higher risk compounds drawdowns fast; lower risk keeps you in the game while you learn. Use the on-page presets or read the 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 % — tap 1% if you’re unsure, or try 0.5% while learning.
- Enter entry price and stop-loss (where your thesis is clearly wrong).
- Optional: add a target to check R:R before you size up.
- Buy only the suggested share count (or fewer). Copy the trade card into a journal.
- Practice the habit in our stock market simulator before using real money.
Pair sizing with stops and R:R
Position size assumes you already know the stop. Pick or sanity-check that level with the stop-loss calculator, then confirm whether the setup’s upside is worth the risk with the risk reward calculator. Same risk dollars on a 2:1 idea beats the same dollars on a coin-flip target.
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. Review whether risked dollars are producing acceptable returns with the investment return calculator.
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.
- Ignoring R:R: A perfect 1% risk on a 0.5:1 target can still be a poor bet if wins don’t outpay losses.
Frequently asked questions
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Educational use only — not financial advice. Markets involve risk of loss. Always do your own research.
