Position Size Calculator
Size every trade from your risk budget, not from a gut feeling
Your inputs
How position size is calculated
Position sizing is the only input in a trade you fully control. You cannot make a setup win, but you can decide exactly how much it costs you when it loses. The formula works backwards from that loss:
risk amount = account balance × risk %
stop distance = |entry − stop| ÷ entry
notional = risk amount ÷ stop distance
position size = notional ÷ entry price
margin needed = notional ÷ leverageWorked example
You have a $10,000 account and risk 1% per trade, so $100 is on the line. You want to long at $100 with a stop at $95 — a 5% stop distance. Your notional is $100 ÷ 0.05 = $2,000, which is 20 units. At 10x leverage that position needs $200 of margin.
Notice what leverage did and did not change. It did not change the $2,000 position or the $100 you stand to lose. It only changed the margin from $2,000 down to $200 — and it moved your liquidation price to roughly $90, comfortably beyond the $95 stop. Push to 25x and liquidation climbs to about $96, inside your stop. The trade would be closed by the exchange before your own risk management ever triggered.
The mistake almost everyone makes
Picking the position size first and discovering the stop afterwards. Done that way, risk is whatever happens to be left over, and it varies wildly from trade to trade — which makes your results impossible to read. Two hundred trades at a consistent 1% tell you whether you have an edge. Two hundred trades at somewhere between 0.4% and 9% tell you nothing except how lucky you got on the big ones.
If the size this calculator returns looks uncomfortably large, that is useful information: your stop is too tight for the asset's volatility. Widen the stop and the size drops automatically, with your dollar risk unchanged. Read how liquidation works for the mechanics behind the liquidation estimate above.
Frequently asked questions
How do I calculate position size?
Divide the cash you are willing to lose by the distance to your stop loss. If you have a $10,000 account, risk 1% ($100), and your stop is 5% away from entry, your position is $100 / 0.05 = $2,000 notional. Leverage does not change this number — it only changes how much margin you post to hold it.
What percentage should I risk per trade?
Most professional risk frameworks land between 0.5% and 2% of account equity per trade. At 1% you can lose 20 trades in a row and still have 82% of your account. At 10% the same streak leaves you with 12%. The lower number is not timidity, it is what keeps you solvent long enough for an edge to show up.
Does leverage change my position size?
No. Position size is set by your stop distance and risk budget. Leverage only determines the margin required to hold that position. Using 20x instead of 5x on the same $2,000 notional frees up margin but does not change your loss if the stop is hit — it does move your liquidation price much closer, which can take you out before the stop does.
What if my stop is very tight?
A tighter stop means a larger position for the same dollar risk, which means a higher liquidation risk and more fee drag. Very tight stops also get hit by ordinary noise. If the size the calculator returns feels alarming, that is the calculator telling you the stop is too tight for the volatility of the asset, not that you should override it.