In unified margin (UM) mode, you can trade spot, margin, futures, 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.
Level 
Name 
Explanation 
Formula 
Currency 
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 amount  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 
Initial margin for all derivatives settled in a currency 
The calculation of initial margin in a currency is the same as the classic mode.
Portfolio margin: please see here for details 

Maintenance margin 
Maintenance margin for all derivatives settled in a currency 
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 amount= 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) 

Accrued interest 
BIT calculates the hourly accrued interest based on the borrow rate and the user’s liabilities every hour on the hour. Accrued interest is the accumulated undeducted interest from the last settlement time(8:00 UTC) to the latest interest calculation time. 
Accrued interest =Σ(hourly borrow rate * liability) (The accrued interest in the current session) 

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

Level 
Name 
Explanation 
Formula 
Account 
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 