Most beginners obsess over which trade to take and ignore the question that actually determines whether they survive: how big should the trade be? Position sizing is the unglamorous skill that separates traders who last from traders who get liquidated. The good news: it’s just one formula.
Why position size matters more than the entry
You can take a perfect setup and still blow up if your position is too big. You can take a mediocre setup and be fine if it’s sized correctly. Position sizing is what converts “risk 1% per trade” from a slogan into an actual number of dollars and coins.
The formula
Position Size = (Account × Risk%) ÷ (Entry Price − Stop Loss Price)
Three inputs, all of which you control:
- Account balance — your total trading capital.
- Risk % — how much of the account you’ll lose if the stop hits (keep it to 1-2%; see our risk management guide).
- Stop distance — how far your stop loss sits from your entry.
A worked example
Say you have a $10,000 account and you’ll risk 1% — that’s $100 you’re willing to lose on this trade. Your analysis puts the stop loss 2% away from your entry price.
Position size = $100 ÷ 0.02 = $5,000 of notional exposure.
If the trade hits your stop, you lose exactly $100 — your predefined 1%. No surprises. That’s the entire point: the stop distance and risk percentage decide the size, not your gut feeling or how confident you are.
The insight most people miss
Notice what doesn’t appear in that formula: your leverage setting. Your actual dollar risk depends on stop distance and position size — not on whether you set 10x or 50x. You can use high leverage and still risk only 1%, as long as the position is sized correctly. (More on this in our leverage guide.)
This is liberating once it clicks: leverage isn’t the enemy, oversizing is.
Build the habit
Before every trade, calculate your size from the stop, not the other way around. Plenty of traders keep a simple calculator or spreadsheet open to do this in seconds. Over hundreds of trades, consistent sizing is what keeps a losing streak from becoming a catastrophe.
Nothing here is financial advice — please read our disclaimer.
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