Position modes in X-Perps, and why is my maximum position size capped?

What is One-way position mode?

Applies to: X-Perps contracts while your position mode is set to One-way.

In One-way mode you hold one direction on a contract at a time — either long or short, not both. Your exposure on that contract is a single net position: however many orders you place, the contract shows one position, with one size and one entry price.

Position mode is a separate setting from margin mode and from leverage. Margin modes are explained in What are the margin modes in X-Perps: selected margin and isolated margin? and leverage is explained in How does leverage work in X-Perps trading?.

What happens if I place an order in the opposite direction in One-way mode?

Applies to: X-Perps contracts in One-way mode.An order in the opposite direction reduces the position you already hold, before it does anything else. If you hold a long and you sell, the sell reduces the long. If you hold a short and you buy, the buy reduces the short. The rule works the same way whichever direction you opened first.

So size the order against what you actually hold. Check the remaining size in Positions, and check your order history, before you place it — an order sized against the wrong number is the most common reason a position ends up smaller than intended, or closed when you meant to keep it.

What happens if I add to a position in the same direction in One-way mode?

Applies to: X-Perps contracts in One-way mode.

Adding in the same direction doesn't create a second position. The new order is merged into your existing net position: the size increases, and the entry price is recalculated as the average across your fills. That average is what your unrealised PnL and your liquidation price are then measured against, so adding at a worse price moves your average entry towards that price.

If you're looking for the second position and can't find it, check the size and entry price on the existing one — the add is visible there rather than as a separate line.

What is Hedge position mode, and how do I close one side?

Applies to: X-Perps contracts while your position mode is set to Hedge.

In Hedge mode you can hold a long and a short on the same contract at the same time.

Closing therefore works differently from One-way mode. To close one side, use the close action on that specific position. An order placed in the opposite direction is a new order on the other side — it isn't a close, and it leaves the first position open. See the OKX X-Perps Guide for how the two modes work.

When can I switch between One-way and Hedge position mode?

Applies to: changing position mode on X-Perps contracts.

You can change position mode only when you have no open positions and no pending orders on the affected contracts. Close the positions, cancel the open orders, then change the position mode in the trading page settings.

Changing your account mode is a different setting with its own requirements. See Who can access X-Perps? guide.

Why is my maximum position size smaller than my balance and leverage suggest?

Applies to: X-Perps contracts, per contract.

Leverage isn't the only thing that limits your position size. X-Perps use position tiers: as a position gets larger it moves into a higher risk tier, and each higher tier requires more maintenance margin and allows a lower maximum leverage. The largest position you can open is therefore normally smaller than "balance × maximum leverage" suggests, and the gap widens the larger the position gets.

Your account's current maximum for a contract is shown in the order panel when you set your size. If the maximum you're offered is lower than you expected, that's the tier that applies to that contract at that size, rather than an error on your account.

Why can I open a larger position on one contract than on another with the same balance?

Applies to: X-Perps contracts, per contract.

Tiers are set per contract, so the same balance can support very different position sizes on two different contracts. A contract with less depth carries tighter tiers than a heavily traded one, which is why its cap can be much lower at the same balance and the same leverage.

Per-contract specifications are published in the X-Perps contract specifications. Check the specification for the contract you're trading rather than assuming the limits carry across from another contract.

What unit is my order size, and the limit in an error message, expressed in?

Applies to: order size and size-limit messages on the X-Perps order panel.

A size limit is expressed in the same unit as the size field it applies to. If a message quotes a number that looks far larger or far smaller than the amount you meant to trade, check which unit the size field is currently using before you compare that number with your balance — a figure in the base asset and a figure in the quote currency aren't comparable, even when both describe the same order.