Perp Position Calculator

How to use this tool

The mistake most new traders make is equating "leverage" with "risk multiplier". 10x leverage does not mean your PnL multiplies by ten — it sets the ratio between notional value and posted margin. What actually decides how fast you blow up is the percentage distance from entry to liq price. The calculator lays that out: instead of showing "10x", it shows "BTC drops 9.6% and your collateral is gone".

Worked example: 1,000 USDT margin, 10x, BTC long at 60,000. Notional is 10,000 USDT, quantity around 0.1667 BTC. With MMR at 0.4%, liq price lands near 54,240 — 9.6% from entry. A single 9% pullback in BTC erases the principal. Stated like that, the trade feels far less abstract than "10x".

Now bump leverage to 25x with the same margin: liq price moves up to about 57,600, leaving only 4% of headroom. That's why we keep this number printed in the most visible spot on the trade plan.

The math behind it

Notional N = Margin M × Leverage L
Quantity Q = N / Entry price P

Long liq price  = P × (1 - 1/L + MMR)
Short liq price = P × (1 + 1/L - MMR)

Long distance to liq = (P - liq) / P
1% reverse PnL = ±0.01 × N
Isolated max loss = M (Cross max loss = full account equity)

MMR on OKX varies by position tier. Majors like BTC and ETH carry roughly 0.4% MMR on small positions; obscure coins or large positions are materially higher. The formula above ignores funding accumulation, the OKX liquidation fee (~0.05%), and slippage, so real liquidations typically fire a touch earlier than the theoretical price.

Common mistakes

"Isolated caps my loss at margin, so it's effectively risk-free." Not quite. When liquidation fires in a thin book or during a flash crash, the actual fill can be worse than the theoretical liq price. Your margin is gone, and in extreme cases the position enters clawback (the insurance fund covers the gap, but your collateral is already at zero).

"Cross is safer because there's more equity backing the trade." Cross does push the liq price further away, but when it does trigger, you lose the entire account equity, not just this trade's collateral. It's a trade between probability and magnitude — neither mode is universally better.

"OKX offers 125x, so the platform thinks it's reasonable." Offering 125x is providing a tool, not a recommendation. Hourly realised volatility on BTC routinely exceeds 0.5%, so 125x liquidates on a 0.8% adverse move. The mathematical expectation of trading that size is negative unless your holding time is measured in minutes.