Isolated vs cross margin on Hyperliquid: which to use

The difference in one line each

Cross margin uses your whole account as collateral for every cross position. Maximum efficiency, and every position is connected to every other one.

Isolated margin allocates a specific amount of collateral to one position. That position can lose at most what you gave it, and nothing else in the account is exposed to it.

Strict isolated is isolated with margin removal disabled, so collateral cannot be pulled back out of the position.

What it changes in the liquidation formula

From the liquidation documentation, the term that differs between modes is the margin available:

margin_available (cross)    = account_value - maintenance_margin_required
margin_available (isolated) = isolated_margin - maintenance_margin_required

That single substitution is the whole distinction, and it has a consequence people miss.

In cross margin, your liquidation price on one position moves when unrelated positions move. A winner elsewhere pushes it away; a loser pulls it closer. A trade you were not thinking about can liquidate the one you were.

In isolated margin, the liquidation price is fixed by the collateral you allocated. It does not move because of anything else you do.

When each is the right choice

Use isolated when you are learning, when you are trading something illiquid or unusually volatile, when you want the risk on a specific idea capped precisely, or when you are running several unrelated strategies and want them not to interfere.

Use cross when you are managing a book of positions deliberately, when you are running a hedge whose two legs should support each other, or when capital efficiency genuinely matters because your collateral is working hard.

Use strict isolated when you want to remove your own ability to rescue a losing position by starving another one. It is a commitment device, and for some people that is exactly the right tool.

The practical recommendation

Start isolated. Not because cross is bad, but because isolated makes the arithmetic legible: you allocated this much, the liquidation price is here, the worst case is that number and no more.

Move to cross when you can state, without looking, what your other open positions do to the liquidation price of the one you are about to open. Until then, cross margin is offering you efficiency in exchange for a risk you have not yet learned to see.