Exchanges do not charge one margin rate across an entire position. They split notional into tiers, and the rate climbs as size grows. That single design choice means a large position can be liquidated while a small one at identical leverage survives the same price move. This guide explains the tier table, the boundary trap, and how exchanges partially liquidate across tiers. This is educational content about how margin mechanics work, never a trade recommendation.
What position tiers actually are
The truth is that leverage is not a single setting. Every major derivatives venue publishes a tier table, and it works like a staircase: the larger your position's notional value, the higher the maintenance margin rate (MMR) the exchange applies — and the lower the maximum leverage allowed.
The logic is risk management, not punishment. A $5,000 position can be closed by the exchange in seconds without moving the market. A $5,000,000 position cannot — dumping it creates its own price impact, which makes the exchange's liquidation risk worse, not better. So venues demand more collateral cushion as size grows.
Here is an illustrative tier table for a major BTC perpetual. Real numbers vary by venue and are updated regularly — for example, Bitget re-tiered nine perpetual contracts on 14 October 2026 and applied the new tiers to already-open positions, and BingX adjusted maintenance margin rules for several pairs on 12 October 2026.
| Tier | Position notional (illustrative) | Max leverage | Maintenance margin rate |
|---|---|---|---|
| 1 | up to $100,000 | 100x | 0.5% |
| 2 | $100,000 – $500,000 | 50x | 1.0% |
| 3 | $500,000 – $1,000,000 | 20x | 1.5% |
| 4 | $1,000,000 – $2,500,000 | 10x | 2.5% |
Two facts follow from that table, and they are the whole point of this article. First, your maximum leverage is capped by the tier your position lands in. Second, your liquidation price is a function of the MMR of that tier — so size itself changes how far price can move against you.
The arithmetic: same leverage, different risk
For an isolated long position, the liquidation price is approximately:
Liquidation price ≈ Entry price × (1 − 1 / Leverage + MMR)
Notice what is missing: notional size. It only enters through MMR, which the tier table sets. That is why two positions at "the same 20x" can have different liquidation distances.
| Scenario | Notional at $80,000 BTC | Tier / MMR | Approx. liquidation price | Distance from entry |
|---|---|---|---|---|
| Small account, 20x | $80,000 (1 BTC) | Tier 1 / 0.5% | $76,400 | 4.5% |
| Large account, 20x | $800,000 (10 BTC) | Tier 3 / 1.5% | $77,200 | 3.5% |
Same entry, same leverage, same asset — but the large position is liquidated $800 closer to the entry price. On 10 BTC that is $8,000 of extra risk that has nothing to do with the market and everything to do with the tier table.
Most guides get this wrong by quoting a single MMR. If you have ever wondered why your calculated liquidation price did not match the exchange's, the tier rate is usually the reason — plus the maintenance amount, a small constant that venues subtract from the requirement to smooth the steps.
The tier-boundary trap
Here's the thing that catches people: the tier boundaries are cliffs, not ramps. A position sitting just under a boundary is charged the lower rate on its entire notional. Push it just over, and the higher rate applies — often to the whole position, not only the slice above the line.
That produces two counter-intuitive outcomes:
- Adding margin can make things worse. If you top up a position right below a tier line and that pushes the notional over the boundary, the MMR jumps and part of your fresh collateral is immediately consumed by the higher requirement. You added safety and reduced your own buffer.
- Rounding up size can be more dangerous than it looks. Going from $99,000 to $101,000 of notional is a 2% size increase but can mean a 100% increase in MMR — from 0.5% to 1.0% in our illustrative table. The marginal risk is wildly disproportionate to the marginal size.
The practical takeaway: before adding to a position, check which tier it is in and how close it sits to the next boundary. On most venues the tier table is one click from the contract page. If a top-up would cross a boundary, consider whether the extra size is worth the jump in required margin. You can read the tier table alongside how liquidation price is calculated.
How exchanges partially liquidate across tiers
Because large positions span tiers, exchanges rarely liquidate them all at once. Most venues use a stepped process to avoid dumping a huge order into a thin book.
Here is how the sequence typically runs on a tiered-margin venue:
- Cancel open orders. The engine first cancels any resting orders that would add to the position, freeing their reserved margin.
- Reduce by one tier. If the position is above tier 1, the engine calculates the size needed to bring the position back down one tier and closes only that portion — a partial liquidation rather than a full one.
- Re-check. After the partial close, the engine recalculates the maintenance margin ratio. If it is back above 100%, the process stops. If not, it steps down another tier.
- Full liquidation at tier 1. If the position is already in tier 1 and still fails the maintenance test, the whole position is closed at the mark price.
This is why "partial liquidation" exists as a distinct event. If you ever see a chunk of your position closed without a full wipeout, you hit a tier step — the exchange trimmed you back into a lower tier and gave the position another chance. It is not a bug and it is not a rescue; the remaining position is still on the clock.
Ready to start trading?
Open a free account on OKX →