Lot size is the minimum quantity increment for orders and positions on a contract. Every order must be an exact multiple of the lot size. For example, if a contract has a lot size of 100, you can trade 100, 200, or 300 contracts – but not 150 or 250. The lot size for each contract is listed on the BitMEX Contract Specification page.
How Does Lot Size Affect Order Placement on BitMEX?
Lot size defines the smallest unit in which a contract can be traded or held. It is the minimum increment for both order quantity and position size.
On BitMEX, every order you submit must be an exact multiple of the contract’s lot size. If the lot size is 100 contracts, valid order quantities include 100, 200, 1,000, or any other multiple of 100. An order for 150 contracts would be rejected because it is not evenly divisible by the lot size.
This rule applies to all order types: market orders, limit orders, stop orders, and any other supported order type. It also applies when partially closing a position. The remaining position size must still be a valid multiple of the lot size.
Lot sizes exist to standardise trading and ensure orderly markets. They prevent fragmented order books and ensure every trade settles cleanly.
Where Do I Find the Lot Size for Each BitMEX Contract?
The lot size for every active BitMEX contract is listed on the Contract Specification page. Navigate to the contract you want to trade and look for the “Lot Size” field.
You can also find the lot size in the contract details panel within the BitMEX trading interface. Select a contract from the instrument selector, and the specification panel displays the lot size alongside other parameters such as tick size, maximum leverage, and settlement currency.
Key fields to check alongside lot size
- Tick Size: The minimum price increment for the contract.
- Max Leverage: The highest leverage available for the contract.
- Settlement Currency: The currency used for margin and settlement (e.g. XBT, USDT).
- Contract Value: The notional value each contract represents.
Together, lot size and tick size define the precision of your orders. Lot size controls quantity precision. Tick size controls price precision. Both must be respected for an order to be accepted.