How position sizing actually works on Bybit
Position sizing is the single most important risk control a trader has, and most retail traders on Bybit get it wrong because they think about it the wrong way around. They open the position picker, type a notional value or a number of contracts that "feels right", set a stop loss somewhere on the chart, and discover the size of the loss only after price hits the stop. That is sizing by feeling. The correct way is the opposite: decide how much you are willing to lose first, then let the math choose the position size that produces exactly that loss when your stop is hit.
The math is mechanical. You start with three inputs: your account balance, the percentage of that balance you are willing to risk on a single trade (almost always between 0.25% and 2% for swing traders), and the distance between your entry and your stop. Multiply balance by risk percent and you get a dollar number — call it your "risk amount". Divide that risk amount by the absolute price difference between entry and stop, and you get the position size in contracts. That is it. Leverage is a separate concern: it controls margin requirement, not loss size, because your loss is bounded by where your stop sits, not by how much margin Bybit asks you to post. A 10x leverage and a 25x leverage on the same trade with the same stop loss have the same dollar loss when the stop hits — they only differ in how much of your wallet sits parked as initial margin.
Why traders blow up despite using stops
The trap is liquidation. Bybit calculates a liquidation price that depends on your leverage and your initial margin, and that price is independent of where you placed your stop loss order. If your stop sits past your liquidation price, you do not actually have a stop — Bybit closes you first, at the liquidation price, and charges you a liquidation fee on top of the loss. This happens far more often than retail traders realize, especially on tight stops with high leverage. A 1% stop on 100x leverage will get liquidated long before the stop fires, because the entire margin is consumed by a 1% adverse move.
The calculator above flags this with a red liquidation warning. The rule of thumb: keep your liquidation distance at least twice your stop distance. If you are stopping out at 1.5% adverse and your liquidation sits at 2% adverse, you have no safety buffer — a wick or a brief slippage event during a CME-gap candle can take you out at liquidation prices instead of stop prices, with the difference in basis-points often exceeding your entire planned loss.
Risk percent — what the numbers actually mean
A 1% risk per trade is not a magic number. It is a function of how confident you are in your edge and how many trades per month you take. A scalper running 30 trades per week with a 55% hit rate cannot afford 1% per trade, because a normal 5-loss losing streak (which happens 4-5 times per year on a 55% strategy) would drop the account 5% in a week, and four of those a year would be 20% just from variance. A swing trader taking 2-3 trades per week can run 1-2% per trade comfortably. The math underneath this is the Risk-of-Ruin calculation — a different page on this site is dedicated entirely to that question.
Common Bybit-specific footguns
Three things bite USDT-perpetual traders that the calculator above does not catch automatically. First: if you trade in cross-margin mode, your liquidation distance is computed against your entire wallet, not the isolated position margin — meaning the calculator overstates your liquidation risk for cross-mode positions. The result is conservative, which is the safe direction to err. Second: Bybit's mark price (used for liquidation triggers) can deviate from the index price by up to ~1% during stressed conditions, so on illiquid altcoin perpetuals you can get liquidated when the market price has not yet hit your liquidation level. Third: funding payments accrue every 8 hours on every open position. The calculator gives you the loss size if your stop hits — it does not subtract the funding cost of holding the position, which over multi-day swings can equal half your stop distance. We have a separate article on funding-fee impact linked below.
Used right, position sizing is the boring discipline that turns mediocre traders into long-term profitable traders, and turns reckless traders with edge into blown-up accounts. The math is on this page; the discipline is not. The discipline comes from journaling — recording every trade, comparing planned-loss to actual-loss, and noticing when you scale up "just this one time" because the setup feels different. That feel-different scaling is what kills accounts.
Related
- → Liquidation Price Calculator (Isolated + Cross) — exact liquidation price with maintenance-margin tier.
- → Risk of Ruin Calculator (Kelly-light) — find the right risk percent for your edge.
- → Funding Cost Calculator (over time) — the holding-cost the position-size calc does NOT include.
- → How Funding Fees Destroy Your Crypto Edge — long-form essay on the same dynamic.
Want to track the size and outcome of every Bybit trade automatically?
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