Survivors decide size from how much they can lose, not how much they want to win. The formula: units = (account × risk%) ÷ (entry − stop). Risk 1% per trade and a losing streak barely dents you; risk 20% and two bad trades end the account. Pair this with the liquidation calculator so your stop sits well before liquidation, and the PnL calculator to check the reward is worth the risk. Not sure where to put the stop? Let the market decide with the volatility (ATR) position size calculator.
Position sizing is the only thing that separates accounts that survive from ones that don't
The formula itself takes five seconds. Risk amount ÷ (entry − stop) = units to buy. What takes longer is actually following it when you're convinced the trade is a sure thing.
Standard practice is 1–2% of account per trade. At 1% on a $1,000 account you're risking $10. With a stop 2% below entry on 10x leverage, safe collateral is $10 ÷ (0.02 × 10) = $50. Most beginners would put in $200–300 because "it looks good." That's the difference.
Leverage changes notional, not risk — if you use 10x on $50 collateral your position is $500 notional. The stop needs to sit where it's technically valid, not where it keeps your loss small. Set the stop first, then calculate size.
The leverage figure above is just what your risk-sized notional implies — flexible per-position leverage tiers make it easier to hit that exact number instead of rounding up:
Enter your total account balance — the full capital you trade with, not just this trade.
Set your risk per trade as a percentage (1–2% is the standard survival range).
Enter your intended entry price and your stop-loss price.
Read the position size — that's the notional you should open. Your leverage is whatever this size implies, not a number you pick for excitement.
The theory behind it
Position sizing is the single most important risk skill. Your size should be derived from your stop distance, never from the maximum margin the exchange offers. The formula is: Position size = (Account × Risk%) ÷ stop-loss distance. Risk a fixed small fraction (1%) and it takes roughly 100 losses in a row to blow up — practically impossible with any real edge. Risk 10% and ten losses halve your account. This calculator turns your stop into the exact size that keeps each loss survivable.
Frequently asked questions
How much should I risk per trade?
Most professional traders risk 1–2% of their account per trade. At 1%, a full wipeout requires about 100 consecutive losses, which is statistically negligible with a genuine edge. Higher risk percentages dramatically raise your risk of ruin during a normal losing streak.
Is position size the same as leverage?
No. Position size is the notional value you open; leverage is just position size divided by the margin you post. Size the position by risk first, then leverage is simply whatever that implies — often much lower than beginners expect.
What if I don't use a stop-loss?
Then you can't size properly, because size is derived from your stop distance. Trading without a defined stop means your maximum loss is undefined, which is how accounts get wiped out on a single move.
What risk-reward ratio should I target once size is set?
Size caps what you lose, not what you should expect to win. If you're risking $10 to enter, a 1:1 target only breaks even at a 50% win rate after fees. Most traders aim for at least 2:1 so a sub-50% win rate can still be profitable. Check a specific trade with the risk/reward ratio calculator before sizing it.
Does leverage change the position size this calculator gives me?
No — size comes only from account, risk%, entry and stop. Leverage just determines how much margin you post for that same notional: a $500 position is $500 whether you post $500 at 1x or $50 at 10x, so the dollar risk is identical either way. What leverage changes is your liquidation distance, not your risk — check that separately with the liquidation calculator so a normal stop doesn't sit past your liquidation price.
New to this? Start with our free trading academy — every lesson links to a calculator.