XBTXBJZECETHETCXMRXRPREPLTCFCTRecentAllXBTUSD764.98+0.33%XBTZ16783.64+0.66%ETH7D0.00969-4.81%XMR7D0.010619-0.05%XBJZ1691665+0.47%XBJ7D91666+0.63%XBJ24H91520-0.13%ZECZ160.076760-3.45%REP7D0.004318-1.03%ETC7D0.000995-3.02%FCT7D0.002752+1.07%XRP7D0.00000849-0.70%LTC7D0.00504+0.00%XBT/USD Spot763.25+0.01%XBT/JPY Spot91697.46+0.52%ETH/XBT Spot0.00978-5.42%ZEC/XBT Spot0.0753110-2.42%24H XBT Volatility1.38-29.23%Funding:  @ 0.0785%Time:
Swaps Guide


A Swap Contract is a derivative product that is similar to a traditional Futures Contract in how it trades, but has a few differing specifications:

  1. There is no expiry on the contract and thus no settlement.
  2. Perpetual Swaps mimic a margin-based spot market and hence trade close to the underlying reference Index Price.
  • This is in contrast to a Futures Contract which may trade at significantly different prices due to basis.

The price of Perpetual Swaps are anchored to spot through various mechanisms. The primary mechanism is Funding.

The Funding is similar to the basis applied to a Futures Contract except in a Swap Contract, buyers and sellers exchange interest payments periodically. This rate is based on a combination of the interest rate differential between the base and quote currencies, and a premium / discount between the swap and Mark Price.

Mechanics of a Swap Market

When trading perpetual swap contracts, a trader needs to be aware of several mechanics of the swap market. The key components a trader needs to be aware of are:

  1. Multiplier: How much is one contract worth? You can see this information under the Contract Specifications for each instrument.
  2. Position Marking: Swap contracts are marked according to the Fair Price Marking method. The Mark Price determines Unrealised PNL and liquidation prices.
  3. Initial and Maintenance Margin: These key margin levels determine how much leverage one can trade with and at what point liquidation occurs.
  4. Funding Timestamps: 04:00 UTC, 12:00 UTC and 20:00 UTC.
  5. Funding: Periodic payments exchanged between the buyer and seller every 8 hours. If the rate is positive, then longs will pay and shorts will receive the rate, and vice versa if the rate is negative. Note that you will only pay or receive funding if you hold a position at the Funding Timestamp.

Traders can observe the current funding rate for a contract on the bottom left hand side of the Trade tab under “Contract Details”. Similarly one can view this rate in the individual “Contract Specifications”. You can also observe the Funding History of all swap contracts here.

The calculation and process for the Funding Rate is described further below.


Funding occurs every 8 hours at 04:00 UTC, 12:00 UTC and 20:00 UTC and these are the times at which payments are exchanged between the buyer and seller of the contract. You will only pay or receive funding if you hold a position at one of these times. If you close your position prior to the funding occurring then you will not pay or receive funding.

The Funding Rate is comprised of two main parts: the Interest Rate and the Premium / Discount. This rate aims to keep the traded price of the swap contract in line with the underlying reference price. In this way, the contract mimics how margin-trading markets work as buyers and sellers of the contract exchange interest payments periodically.

Interest Rate Component

Every contract traded on BitMEX consists of two instruments: a Base currency and a Quote currency. For example: XBTUSD, the Base currency is XBT while the quote currency is USD. The Interest Rate is a function of interest rates between these two currencies:

Interest Rate (I) = (Interest Quote Index - Interest Base Index) / Funding Interval
  Interest Base Index = The Interest Rate for borrowing the Base currency
  Interest Quote Index = The Interest Rate for borrowing the Quote currency
  Funding Interval = 3 (Since funding occurs every 8 hours)

Note: Under each Contract Specification page, the source borrow market is stated for each Interest Index.

Premium / Discount Component

Sometimes the swap contract may trade at a significant premium or discount to the Mark Price. In those situations, a Premium Index will be used to raise or lower the next Funding Rate to levels consistent with where the swap is trading. Each swap’s Premium Index is available on the specific instrument’s Contract Specifications page and is calculated as follows:

Premium Index (P) = (Max(0, Impact Bid Price - Mark Price) - Max(0, Mark Price - Impact Ask Price)) / Spot Price + Fair Basis used in Mark Price

To learn more about the Impact Bid Price and Impact Ask Price, please read Fair Price Marking.

Final Funding Rate Calculation

The Funding Rate is next calculated with the Interest Rate Component and the Premium / Discount Component. A +/-0.05% dampener is added.

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

Hence, if (I - P) is within +/-0.05% then F = P + (I - P) = I. In other words, the Funding Rate will equal the Interest Rate.

BitMEX calculates the Funding Rate (F) every minute and then performs a 8-Hour Time-Weighted-Average-Price (TWAP) over the series of minute Funding Rates. This 8 hour TWAP is then the final Funding Rate that will be paid or received at the Funding Interval.

This calculated Funding Rate is then applied to a trader’s XBT Position Value to determine the Funding Amount to be paid or received at the Funding Timestamp.

Funding Rate Caps

BitMEX imposes caps on the Funding Rate to ensure the maximum leverage can still be utilisted. To do this, two caps are imposed:

  1. The absolute Funding Rate is capped at 75% of the Initial Margin - Maintenance Margin. If the Initial Margin is 2% and the Maintenance Margin is 0.5%, the maximum Funding Rate will be 75% * (2% - 0.5%)= 1.125%.
  2. The Funding Rate may not change by more than 75% of the Maintenance Margin between Funding Intervals.

Funding Fees

BitMEX does not charge any fees on funding.

More Information

Further information and examples of Funding Calculations are available.