**What is Perpetuals mark price**

BIT uses make price as the fair price for perpetuals market, for calculating realized P&L and unrealized P&L of positions and generating real-time funding rates.

**Calculation of mark price**

The mark price of BIT is derived using both the BIT index and the fair price of USD margined perpetual swap market as follows:

Mark Price = Index Price + 30 seconds EMA* of (Average of Fair Bid & Ask - Index Price)

*EMA: An exponential moving average (EMA) is a type of moving average (MA) that places a greater weight on the most recent data points. The exponential moving average is also referred to as the exponentially weighted moving average.

Mark Price is limited within 1% from BIT Index against manipulative trading, where 1% is determined by BIT risk team. The price limit will be adjusted according to the market condition, please refer to the BIT announcement on the website.

**How to check the mark price**

Mark price is slightly different from index price, you could track the real-time mark price on the top of the contract trading page.