For the calculation of Unrealized Profit/Loss, Mark Price is used instead of Average Exit Price. Traders can always check the Unrealized Profit/Loss at "Assets" page as well as on the "Positions" tab in real time.
For long position:
A trader buys 4,000 BTCUSD contracts at 5,000 USD, with the Mark Price at 5,500 USD.
Unrealized Profit = 4,000 x (1/5,000 – 1/5,500)
= 0.07272727 BTC
At the 'Positions' tab, the unrealized P&L percentage indicates the percentage of your current unrealized profit/loss with respect to your position margin.