In unified margin (UM) mode, you can trade spot, margin, perpetual, and options at the same time by transferring assets into your unified account. Besides, your assets in different currencies (e.g. BTC, ETH and USDT, etc.) are calculated in USD value and used as margin for placing orders and holding positions for all trading products. The unified account system is divided into a currency dimension and an account dimension, please refer to the following explanation of terms and formulas for more details.
Currency Dimension
Name  Explanation  Formula 
Equity  Equity in a currency in the account  Equity = cash balance + unsettled PNL  accrued interest + options value 
Margin balance  The balance of a currency available as margin  Margin balance = cash balance +unsettled PNL  accrued interest 
Available balance  The amount available for selling, position opening and options trading in a currency  Regular: available balance = max (0, margin balance  initial margin  frozen) Portfolio margin: available balance = max (0, equity  initial margin  frozen) 
Frozen  Amount frozen in a currency due to spot open orders  Frozen = Σ (spot order amount in short leg for each currency) 
Initial margin  The minimum margin amount required for users to open a position. The initial margin is inversely proportional to the leverage used by the user  The calculation of initial margin in a currency is the same as the classic mode.
Portfolio margin: please see here for details 
Maintenance margin  The minimum margin amount required by the user to maintain the position. Maintenance margin is calculated based on the tier corresponding to the notional value of the user's position  The calculation of maintenance margin in a currency is the same as the classic mode.
Portfolio margin: please see here for details 
Unsettled PNL  The sum of profit and loss on all futures and perpetual positions settled in a particular currency in the current session.  Unsettled PNL= realised profit & loss (perpetual and futures) + unrealised profit & loss (perpetual and futures) 
Liability  The liability amount in a currency, interest will be calculated once an hour.  Liability = min (0, equity) 
RealTime Settlement  For all perpetual contracts and options, BIT adopts a realtime settlement system. The realized profits and losses generated from user trading of contracts or options will be immediately transferred to the account balance. On the other hand, the unrealized profits and losses will not be settled daily; users need to close positions to realize and settle profits and losses.  Please read here 
Potential liability  When the equity of a currency is less than the sum of the current initial margin and frozen amount, the difference amount is potential liability, which will take up a certain amount of total USD initial margin.  Potential liability = min (0,equity  initial margin  frozen)  
Short spot initial margin rate  The initial margin rate that potential liabilities take up with in the account dimension  Please read here for short spot initial margin rate 
Short spot maintenance margin rate  The maintenance margin rate that potential liabilities take up with in the account dimension  Please read here for short spot maintenance margin rate 
Delta  The delta of a position in a currency represents the change of position value due to the change in the underlying asset’s price. In other words, delta is how many dollars a position value moves when the price of the underlying asset moves by $1.  Currency delta = sum of positions delta in the currency (derivatives positions)  option value in the currency

Account Dimension
Name  Explanation  Formula 
Total collateral  The USD value of total collateral which is the sum of all collateral currencies calculated with haircut ratio in the unified account.  Total collateral =Σ [max (0,equity) * (100%  haircut ratio) * currency index Σ(liability * currency index)] 
Total margin balance  Sum of USD value of margin balance in all currencies calculated with haircut ratio in the unified account.  Total margin balance = Σ [max (0, margin balance) * currency index * (100%  haircut ratio) + min (0, margin balance) *currency index)] 
Total available balance  Available margin balance for opening margin, futures, perpetual and options positions in the unified account.  Regular: total available balance = max (0, total margin balance  total initial margin  total frozen) Portfolio margin: total available balance = max (0, USD total collateral  USD total initial margin  total frozen) 
Spot order haircut loss  When a spot order is placed or filled, if the long currency haircut ratio is greater than the short currency haircut ratio, there will be a decrease in the total collateral, and the decreased amount is spot order haircut loss.   
Total frozen  Sum of USD value of haircut losses in all spot trading pairs in the unified account.  Total frozen = sum of all haircut losses 
Total liability  The sum of each currency's liability amount converted to USD.  Total liability = Σ(currency liability * USD Index) 
Total unsettled PNL  The sum of each currency's unsettled profit and loss converted to USD.  Total unsettled PNL = currency unsettled PNL * USD Index 
Total initial margin  USD value of initial margin required by all positions, pending orders and potential liabilities in the unified account.  Total initial margin= Σ(initial margin * currency index) + Σ(potential liability * short spot IM rate * currency index) 
Total maintenance margin  USD value of maintenance margin required by all positions, pending orders and potential liabilities in the unified account.  Total maintenance margin= Σ (maintenance margin * currency index) + Σ(potential liability * short spot MM rate * currency index) 
Total IM% (total initial margin rate)  Account risk indicator  Regular: total IM% = [total initial margin + total frozen] / total margin balance Portfolio margin: total IM% = [total initial margin + total frozen] / total collateral 
Total MM% (total maintenance margin rate)  Account risk indicator  Regular: Total MM%= total maintenance margin/ total margin balance Portfolio margin: Total MM%= total maintenance margin/ total collateral 