Position Size Calculator
Risk a fixed, chosen amount on every trade — enter your account size, the percent you're willing to lose, your entry, and your stop. Get the exact share count. The formula is shown in full because you should never trust a sizing tool you can't audit.
Check your inputs — stop must be below entry, and all values positive.
Why size before you buy
Most retail losses come not from bad entries but from oversized ones — a position so large that one normal stop-out wrecks the month. Risk-based sizing flips that: you choose the loss you can tolerate first, and the market's distance to your stop tells you how many shares that loss buys. It is the single most transferable risk control in trading — same math in every market.
This calculator is the last step of our research workflow: business quality → valuation ceiling → thesis breaks → then size the position and check the timing signal. A well-sized position in a business you don't understand is still a bad trade — size the research first.
FAQ
What is the formula?
Shares = (Account size × Risk %) ÷ (Entry − Stop). Example: $10,000 at 1% risk ($100), entry $50, stop $45 → $100 ÷ $5 = 20 shares — a $1,000 position risking exactly $100.
How much should I risk per trade?
Systematic traders commonly use 0.5–2%. The honest answer: whatever keeps your worst realistic losing streak survivable. Ten losses in a row at 2% is an 18% drawdown — survivable. At 10%, it's 65% — not.
Does it work for any market?
Yes — the math is price-based: US, Hong Kong, China A-share, Korea, India, ETFs, crypto (adjust for lot/contract sizes where applicable).
Is this financial advice?
No — it is arithmetic. The tool shows the math so you can check it; the decisions, and the responsibility, stay yours.
Pair sizing with research
Balance Labs scores business quality and valuation before the timing signal — so you size positions in businesses worth sizing. Free plan, no card.