Initial margin is what you must post to open. Maintenance margin is the minimum equity the position must retain to stay open. Fall below maintenance and the position is closed for you.
The distance between them is the room you have. Two positions at the same nominal leverage can have quite different survival characteristics if their maintenance requirements differ, which is why the advertised multiple is an incomplete description of risk.
The tier that surprises people
Maintenance requirements are usually tiered by position size. A larger position faces a higher maintenance percentage, because the venue would have more trouble unwinding it.
So scaling into a winner can quietly move you into a tier with a tighter requirement, which brings your liquidation price closer even though the position is profitable and you added nothing to your risk in the usual sense. This is one of the few places in trading where being right and adding is itself a mechanism that increases fragility.
Why the buffer matters more than the multiple
Two traders both say “10x”. One is using isolated margin with exactly the initial requirement posted, and a small adverse move ends the position. The other posts substantially more than required, so the same move is uncomfortable rather than terminal.
Identical leverage in the marketing sense, completely different survival. This is why the useful question is never the multiple but how far price must travel before the engine acts — the arithmetic in liquidation price and leverage.
And it is judged on the mark
Worth restating because it changes the calculation: the equity being tested against maintenance is computed from the mark price, not the last trade. Your buffer is measured against a number that is not the one on your chart.
Where that margin sits — behind one position or behind all of them — is the separate decision covered in isolated versus cross margin.