Profit and loss (PnL) is the raw dollar result of the trade: quantity held times the price move, in your favour or against you. It does not care how much margin you posted.

Return on equity (ROE) divides that PnL by the margin you actually put up. Post $1,000 at 10x and you control a $10,000 position, so a $300 gain on the position is a 30% return on your $1,000. Same trade, same PnL, but ROE is the number that tells you what happened to your account.

At 10x, your $1,000 controls $10,000 of coin. A 1% move in the coin is a $100 swing on the position, which is 10% of your margin. The price moved 1%; your equity moved 10%.

This is symmetric. The same 10x that turns a 2% rise into a 20% gain turns a 2% drop into a 20% loss, and a 10% drop wipes the margin out entirely. Leverage does not change the odds of the trade, it changes how much of your account rides on each percent.

A taker fee around 0.05% per side sounds trivial until leverage scales it. On a $10,000 position that is about $5 in and $5 out, $10 against a $1,000 margin, so you start the trade down 1% ROE before the price does anything.

Funding is the other slow leak. On a perpetual you pay or receive funding every few hours depending on which side is crowded. Hold a leveraged position for days on the wrong side of funding and it compounds into a real drag that a single PnL snapshot never shows.

Decide the loss you can accept in dollars first, then work backwards to a position size and leverage that puts your liquidation price outside the range the coin normally moves in. The PnL calculator on this site does the forward math; the liquidation calculator does the backward check.

If a plan only works at 25x or higher, the plan is that the coin does not have an ordinary bad day before your target. That is a bet on variance, not on direction.