Cross margin lets eligible collateral in a shared margin pool support several crypto futures positions; isolated margin assigns collateral to a specific position. The choice changes which funds can support losses, not the price exposure of an unchanged trade. Before choosing, identify the pool's exact scope and whether automatic or manual margin additions can expand an isolated allocation.
A margin-mode label answers a funding question: where may support for this position come from? It does not tell you whether the trade is sensible, how much the price can move, or whether an exit will execute. This guide focuses on that collateral boundary for futures and perpetual contracts. Borrowed spot-margin products can use similar labels with different account and repayment rules.
Start with the boundary, then compare the modes
Under cross margin, losses on one position can consume resources that also support other positions in the same eligible pool. Profits elsewhere may provide support too. Under isolated margin, each position has its own allocated support. OKX's futures-mode documentation describes sharing among products settled in the same cryptocurrency and separating position risk in isolated mode. That settlement-currency scope matters: “cross” does not universally mean every asset held anywhere at an exchange. OKX futures-mode cross-margin rules.
| Question | Cross margin | Isolated margin |
|---|---|---|
| What supports the position? | Eligible collateral in the relevant shared pool | Collateral allocated to the position |
| Can another position change its support? | Yes, through the shared pool's gains, losses and obligations | Its allocated support is separate, subject to the venue's rules |
| What needs monitoring? | Shared equity, requirements and all participating exposure | Position margin, requirements and any margin additions |
| What is easy to misunderstand? | Initial margin is mistaken for the total collateral exposed | The initial allocation is mistaken for a permanent boundary |
The boundary can also depend on account mode. Bybit's Unified Trading Account comparison says its margin-mode choice applies to the whole account; its cross mode can value multiple collateral assets in USD. Do not assume every venue offers a per-pair switch or the same collateral pool. Bybit Unified Trading Account margin-mode comparison.
The same trade has the same price loss
Consider a deliberately simplified, hypothetical USDT-linear BTC long. The position is 0.05 BTC at an entry of 60,000 USDT per BTC. Entry notional is 0.05 × 60,000 = 3,000 USDT. At a nominal 10× leverage setting, notional divided by leverage is 300 USDT. Treat that as the example's initial allocation; actual opening requirements can include fees and venue buffers.
The account starts with 1,000 USDT and no other positions or obligations. In the isolated setup, allocate 300 to the position and leave 700 outside it. In the cross setup, assume all 1,000 is eligible shared collateral. The quantity, contract and entry are identical.
The leverage-versus-position-size comparison develops why changing support for an unchanged quantity does not multiply its dollar price PnL. The collateral ledger here keeps that quantity fixed too.
At a hypothetical mark of 57,000, gross unrealized price PnL is:
0.05 × (57,000 − 60,000) = −150 USDT
That loss is the same in either mode. The following is a collateral ledger at that observation, assuming the position remains open and satisfies its applicable maintenance requirements. It is not a liquidation simulation. Fees, funding, collateral discounts and all other activity are excluded.
| Setup after the price move | Position quantity | Gross price PnL | Collateral accounting at this snapshot | Total modeled equity |
|---|---|---|---|---|
| Isolated, no added margin | 0.05 BTC | −150 USDT | 150 position equity; 700 outside its allocation | 850 USDT |
| Isolated, owner adds 200 USDT | 0.05 BTC | −150 USDT | 350 position equity; 500 outside its allocation | 850 USDT |
| Cross, full 1,000 eligible initially | 0.05 BTC | −150 USDT | 850 shared equity before any applicable reservations | 850 USDT |
Adding margin changes the source of support. It does not reverse the 150-USDT price loss or buy more BTC in this construction. The isolated contribution rises from 300 to 500, while total equity stays 850. Calling the transfer a recovery would confuse funding with performance.
Likewise, switching the same position into cross mode does not improve its gross price PnL. It can give the position access to more collateral, changing the account's exposure to continued losses. The extra room is a commitment of resources, not a free reduction in risk.
An isolated allocation can grow without another trade
A realistic failure is enabling automatic replenishment and then treating the original isolated margin as a fixed budget. Bybit documents Auto-Margin Replenishment for supported isolated USDT perpetual, USDT expiry and USDC perpetual contracts. When enabled, it can move available account funds into a position as its margin approaches the liquidation threshold. The venue also says it cannot guarantee avoidance of liquidation. Bybit Auto-Margin Replenishment rules and product scope.
In the fictional ledger, a 200-USDT addition leaves 500 outside the position instead of 700. An automatic mechanism would require the same accounting discipline: record every contribution and the authority that allowed it. Do not assume a particular replenishment amount or trigger from this example.
Manual rescue transfers create the same budgeting issue. A trader may repeatedly add small amounts and remember only the starting allocation. Record cumulative contributions alongside current position equity. If a separate account boundary is needed, use the exchange subaccount worksheet to examine balances, collateral and transfer authority.
Cross margin needs an account-wide failure scenario
A shared pool must be reviewed as a group. If two participating positions lose value together, each reduces the resources available to support the other. A profitable position does not establish that the combined account remains adequately margined.
Extend the cross ledger with a separate, hypothetical 200-USDT loss from another participating position. Shared equity falls from 850 to 650 USDT before costs. That arithmetic alone cannot establish whether liquidation occurs: the second position also has its own maintenance requirements, and the venue's account calculation must include them.
For Bybit UTA cross margin, the documented trigger is Account Maintenance Margin Rate reaching 100%; its displayed liquidation price is an estimate. In isolated mode, the documented trigger uses mark price reaching the position's liquidation price. The mark-price and liquidation guide explains why an ordinary trade-price chart can miss that distinction. Bybit margin-mode trigger comparison.
Complete this worksheet before enabling automation
| Record | Write down | Recheck when |
|---|---|---|
| Exact scope | Venue, account type, contract and margin mode | Account or product mode changes |
| Collateral boundary | Eligible assets and whether the pool is position, settlement-currency or account based | An asset is enabled as collateral |
| Addition authority | Automatic replenishment setting, manual-transfer owner and contribution budget | Margin is added or settings change |
| Shared obligations | Other positions, open orders and relevant charges | Another process changes exposure |
| Risk observation | Venue-defined metric, its timestamp and any position threshold | Equity or requirements change |
| Exit evidence | Stop source, order type and how fills are verified | Exit orders are amended or interrupted |
Keep the stop plan separate from the collateral plan. Use the stop-distance sizing worksheet to translate a chosen loss budget into quantity; margin allocation alone does not supply that budget. Isolated margin does not promise a stop fill, and cross margin does not ensure enough time to react. The stop-market versus stop-limit guide covers activation and execution limits. Recurring charges also deserve their own record; use the perpetual funding-cost ledger to distinguish them from price PnL.
Choose a mode only after the completed worksheet matches the intended funding boundary. If the pool scope, replenishment setting or monitoring metric is unknown, the risk plan is incomplete. A mode selection should be a recorded account decision, with a fresh review whenever its supporting resources change.
Editorial method: Prepared with AI assistance on 23 October 2026 from the official exchange documentation linked above. The collateral ledger and second-position extension are original hypothetical teaching examples. They omit real liquidation calculations and do not establish KLINEO support for a venue setting.