Position size calculator
How big to enter so that a stop-out costs exactly what you're willing to lose. Enter deposit, risk, entry and stop — the calculator returns position size, margin, safe leverage and liquidation price for longs and shorts.
Liquidation is approximate: isolated margin, maintenance margin ≈ 0.5%. The exact price depends on the exchange and position size.
How to calculate position size
Position size isn't "whatever feels OK" — it's derived from the stop. First decide how much money you're willing to lose on this trade, then divide that amount by the distance to the stop in percent:
This way the loss at the stop is always the same — exactly the chosen share of your deposit — whether the stop is tight or wide. A tight stop gives a bigger position, a wide one gives a smaller position.
Worked example
Deposit $1,000, risk 1% → you're willing to lose $10.
Entry $100, stop $97 → 3% to the stop.
Position size = $10 ÷ 0.03 = $333 (≈ 3.33 coins).
At 5× leverage your own money in the trade is $333 ÷ 5 = $67. At the stop you lose $10 — not $67 and not $333.
Leverage doesn't change risk
A common mistake is to think 20× is four times more dangerous than 5×. The loss at the stop depends only on position size and stop distance. Leverage decides something else: how much of your money the exchange locks as margin. Leverage becomes dangerous when liquidation sits closer than your stop — then the exchange closes the position before your stop triggers, and you lose more than planned.
How to pick leverage so liquidation stays beyond the stop
With isolated margin, liquidation happens roughly 1 ÷ leverage − 0.5% away from entry. To keep it beyond the stop with a buffer, the calculator uses this maximum:
The lower bound is the leverage below which your deposit can't cover the position: size ÷ deposit. Any leverage in between gives the same risk at the stop; lower leverage means more money in margin but liquidation further away.
How much to risk per trade
Even a good strategy has losing streaks. Here's what 10 stop-outs in a row do to a deposit at different risk levels:
- 1% risk — minus 9.6% of the deposit;
- 2% risk — minus 18.3%;
- 5% risk — minus 40%;
- 10% risk — minus 65%, and to get back to break-even you'd need to almost triple what's left.
That's why most professional traders keep risk at 1–2% per trade: a losing streak becomes an annoyance, not a blow-up. We tested this on 1,245 real backtest trades in the guide «How much to risk per trade», and how to place the stop itself is covered in «ATR stop loss».
Don't forget fees
Fees are charged on the position size, not on margin. At a 0.055% taker fee, entering and exiting a $333 position costs about $0.37 — trivial for one trade, but noticeable over hundreds of trades with tight stops.
FAQ
What is position size?
The full value of the position in dollars: number of coins × entry price. Profit, loss and fees are all calculated from it. Margin is just the part of the position the exchange locks from your deposit: size ÷ leverage.
Does the calculator work for shorts?
Yes. If the stop is above entry it's a short, if below — a long. The calculator detects the direction and computes liquidation and take profit accordingly.
Which leverage should I choose?
Any leverage within the "safe" range gives the same risk at the stop. Lower leverage means liquidation further away and more money in margin. Above the maximum, liquidation may trigger before your stop.
Why can the loss at the stop be bigger than calculated?
Because of slippage on sharp moves, fees and funding, or if liquidation was closer than the stop. That's why stops are placed by structure and volatility, and leverage is kept in the safe range.
Can I skip the manual math?
Yes. AI Trading Room calculates the position size for your deposit and risk automatically in every coin breakdown and every scan signal — with a leverage hint.
Position size in every signal — automatically
AI Trading Room is an AI analyst in Telegram: a breakdown of any coin with entry, stop, take profits and size for your deposit. Market news every morning — in the @the_crypticle channel (in Russian).