> For the complete documentation index, see [llms.txt](https://docs.satori.finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.satori.finance/perpetual-trading/funding-costs.md).

# Funding Costs

The price of perpetual contracts is anchored to the spot index price through a funding fee mechanism. Long positions pay short positions when the future is trading at a premium, while short positions pay long positions when the future is trading below the spot price. The platform does not retain any of these fees. 

#### Funding Fee Rate Calculation <a href="#funding-fee-rate-calculation" id="funding-fee-rate-calculation"></a>

The funding fee is charged every hour and consists of two components: the interest rate and the premium index.&#x20;

* Interest Rate: Currently set at 0.03%(need double check) per day.&#x20;
* Premium Index: Calculated for each market at random intervals within each minute using the following formula:&#x20;

&#x20;  B: *Impact bid price (average execution price to close a long position through a market sell).*&#x20;

&#x20;  A: *Impact ask price (average execution price to close a short position through a market buy).*&#x20;

&#x20;  I: *Spot index price.*&#x20;

&#x20;  Impact Notional Value: Set to 800 USDT divided by the Initial Margin Ratio of the market.&#x20;

The total premium index for an hour is the average of all premium indices calculated during that hour. The funding fee rate will equal the hourly interest rate if the premium index is within 0.05% of the hourly interest rate.&#x20;

#### Funding Fee Rate Cap <a href="#funding-fee-rate-cap" id="funding-fee-rate-cap"></a>

The absolute value of the funding fee rate is capped at 0.75%.


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