Position Size Calculator
How many shares should you buy? Enter your account size, risk percentage, entry, and stop — we'll tell you the exact share count that keeps your loss within your plan.
Inputs
Total capital you're trading with.
Add a target to see your reward-to-risk ratio.
Result
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Enter your account size, risk %, entry, and stop above —
the result appears instantly.
How position sizing works
The math is simple, the discipline is hard. Most retail traders blow up not because their entries are wrong but because they size positions on conviction, not on risk.
The formula
Risk Dollars = Account Size × Risk % Stop Distance = | Entry − Stop | Shares = Risk Dollars ÷ Stop Distance Position Size $ = Shares × Entry
The 1%, 2%, 2.5% rule
Professional traders cap the risk on any single trade at a small fraction of their account. The most common values are 1% (conservative), 2% (the textbook standard), and 2.5% (aggressive but still survivable). At 2% per trade, even ten consecutive losing trades only draws down ~18% — survivable. At 5% per trade, ten losses takes you down ~40% — career-ending.
Example
$25,000 account, 2% risk = $500 max loss per trade. You want to buy AAPL at $185 with a stop at $180 — that's a $5 stop distance. $500 ÷ $5 = 100 shares. Position size: $18,500 (74% of your account, which is fine because risk is still capped at $500). If AAPL hits your stop, you lose exactly $500 — no more.
What this calculator doesn't cover
- · Slippage — your stop won't fill exactly at the published price during fast moves
- · Commissions — most US brokers are now $0/trade, but options and international are not
- · Overnight gap risk — earnings or news can blow through your stop
- · Margin / leverage — if you're trading on margin, real risk is amplified
Ready to trade with an edge?
Halal-compliant signals.
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Mezan Research delivers AI-powered analysis on US stocks filtered for halal compliance. Position sizing is just the discipline. We bring the signals.