The order panel gives you three ways to set size: type it directly, use the percentage slider, or work backwards from risk with the position size calculator. This article covers each - and the two ceilings every order has to fit under.
Entering a size
- Type it - enter the amount in the size field. The unit selector switches between the pair's base asset (for example BTC) and USDT, and the panel converts between them live.
- Slider - drag to use a percentage of your maximum available margin, from 0 to 100%.
- Calculator - the calculator icon next to the TP/SL row opens the position size calculator, where you can size a trade from the risk you want to take rather than the other way round.
Above the field, Avbl shows the margin currently available to trade with. Below the buttons, Cost shows the margin this order will reserve and Max the largest size you could open right now.
Ceiling one: your margin
Your maximum position is margin × leverage, less fees and slippage - the estimated costs of the fill are reserved up front, which is why the max is slightly below the simple multiplication. Raising leverage raises the max; see the Adjusting Leverage article.
Ceiling two: the exchange order cap
Each pair also has a hard cap sourced live from Bybit - the largest market order the real exchange accepts for that pair. The panel shows your usage against it, for example 0 / 150 BTC on BTCUSDT, and will tell you when a size is limited by the exchange order cap rather than by your margin.
This cap exists because CPX simulates real trading conditions: a position that could not actually be filled on the live order book is not allowed in the simulation either.
FAQ
Why is my max size smaller than margin times leverage? The estimated trading fee and slippage for the fill are set aside before the position opens, so the usable maximum is slightly lower.
Why can I not open the size I typed? One of the two ceilings is binding - either the order needs more margin than you have available, or it exceeds the pair's exchange order cap. The panel shows which.
Does the cap change? Yes, it is streamed live from Bybit per pair and can move with market conditions.
Does the unit I type in matter? No - base asset and USDT entry are equivalent; the panel converts at the live price either way.
