Maintenance margin is the liquidation line
You don't lose the trade at zero equity — you lose it when equity hits the maintenance floor. Know that buffer. See exactly where it triggers on the liquidation calculator.
The margin that actually triggers liquidation
Initial margin gets you into the trade; maintenance margin is what gets you out of it. When your equity falls to the maintenance level — typically 0.5% of position value on major pairs — the exchange force-closes you. Not at zero. At 0.5%.
This is why liquidation comes earlier than naive math suggests. At 20x you might think you have a 5% cushion. Subtract the 0.5% maintenance requirement and it's 4.5%. On a volatile alt, tiered maintenance margin can be 1% or more, cutting your cushion further.
The tier detail matters for size: bigger positions face higher maintenance rates. A $50k position on some alts sits in a higher tier than a $5k one — same leverage, same coin, but liquidation lands measurably closer. If you trade size, look up your exchange's tier table rather than assuming the base rate.