The funding fee mechanism anchors the trading price of perpetual contracts to the spot price of the underlying asset.

**Funding Fee = Positional Value * Funding Rate**

Assuming funding payments occur every 8 hours:

- The funding fee is directly exchanged between the buyers and sellers every 8 hours. When the funding rate is positive, long position holders pay the short position holders. When the funding rate is negative, short position holders pay the long position holders.
- If a trader holds a position during the funding fee settlement time, they will either pay or receive funding fee. You can check the funding rate and the next funding fee settlement time on the trading interface:

Due to the complexity of funding fee settlement, the actual settlement time may have a deviation of 1 minute. Please refer to the actual settlement time. Users only need to pay or receive funding fee if they hold the position during the settlement time. If the position is closed before the fee is charged, no funding fee need to be paid.

For example, if the trading interface shows that funding fee will be settled at 08:00:00 UTC, if you close the position at 08:00:03 UTC, the funding fee may not have been settled yet, so you do not need to pay or receive funding fee. Or if you open a position at 08:00:59 UTC, due to the deviation in settlement time, you may still need to pay or receive funding fee.

## How to Calculate Funding Fee

**Funding Fee = Positional Value * Funding Rate**

The funding rate consists of two parts: interest rate differential and premium index.

Pionex calculates the premium index every 5 seconds and then calculates its mean (P) every N* hours.

N* = Funding Interval. If funding fee settlement occurs every 8 hours, then N = 8. If funding fee occurs every 1 hour, then N = 1.

**Funding Rate (F) = Average Premium Index (P) + clamp(Interest Rate Differential (I) – Average Premium Index (P), 0.05%, -0.05%)**

Where: clamp(value, max, min) means to truncate the value to the lower limit min and the upper limit max, i.e.,

- If value < min, return min.
- If value > max, return max.
- Otherwise, return value.

So, if (I-P) is between +/-0.05%, then F = P + (I-P) = I. In other words, the funding rate will be equal to the interest rate differential.

The calculated funding rate will be applied to the trader’s Positional Value, and the corresponding funding fee to be paid or received will be calculated at the respective funding fee settlement time.

**Interest Rate Differential (I) = (Quoted Currency Daily Interest Rate – Base Currency Daily Interest Rate) / Funding Rate Frequency**

- Funding Rate Frequency = 24 / Funding Interval