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BloFin Coin-Margined and USDT-Margined Contracts Calculation

November 18, 2025 at 04:16 PM

Overview

BloFin provides two types of perpetual contract pricing modes:
  • Coin-Margined Contracts: Margin and settlement are in cryptocurrency (e.g., BTC, ETH).
  • USDT-Margined Contracts: Margin and settlement are in USDT.
The two modes have significant differences in PnL calculation, margin characteristics, and forced liquidation mechanics. This document provides a standardized reference for contract calculations.

 

Profit and Loss Calculation

1. Coin-Margined Contracts

Unrealized PnL
  • Long Position: Unrealized PnL = Contract Size × (1 / Entry Price − 1 / Mark Price)
  • Short Position: Unrealized PnL = Contract Size × (1 / Mark Price − 1 / Entry Price)
PnL is denominated in the base coin (e.g., BTC), and price fluctuations affect overall account value.

Realized PnL
  • Long Position: Realized PnL = Contract Size × (1 / Entry Price − 1 / Exit Price)
  • Short Position: Realized PnL = Contract Size × (1 / Exit Price − 1 / Entry Price)
After closing the position, PnL is settled in the base coin.
Example: BTC coin-margined long position, Entry Price 60,000, Exit Price 62,000, Contract Size 0.1 BTC:
Contract value 6,000 USD(equivalent to 0.1 BTC at entry price)
 
Realized PnL = 6000 × (1 / 60000 − 1 / 62000) 
= 6000 x 0.0000005376344
= 0.0032258 BTC
Converted to USDT at exit price:
0.0032258×62,000≈200 USDT
 

2. USDT-Margined Contracts

Unrealized PnL
  • Long Position: Unrealized PnL = Position Size × (Mark Price − Entry Price)
  • Short Position: Unrealized PnL = Position Size × (Entry Price − Mark Price)
PnL is denominated in USDT and is not affected by base coin price fluctuation.
 
Realized PnL
  • Long Position: Realized PnL = Position Size × (Exit Price − Entry Price)
  • Short Position: Realized PnL = Position Size × (Entry Price − Exit Price)
Example: USDT-margined short position, Entry Price 60,000, Exit Price 58,000, Position Size 0.1 BTC: Realized PnL = 0.1 × (60000 − 58000) = +200 USDT
 

Margin Differences

Comparison Item Coin-Margined Contracts USDT-Margined Contracts

Margin Currency

Base Coin (BTC/ETH)

USDT

Margin Value Fluctuation

Yes, fluctuates with coin price

No, stable

Risk Characteristics

Margin shrinks if coin price drops

Stable, controllable risk

Settlement Unit

Base Coin

USDT

PnL Source

Coin price movement + contract price change

Contract price change only

Funding Fee

  • Coin-Margined Contracts Funding Fee = Contract Size × Settlement Price × Funding Rate Unit: Base Coin (e.g., BTC)
  • USDT-Margined Contracts Funding Fee = Position Notional × Funding Rate Unit: USDT
     

Trading Fee

1. Coin-Margined Contracts

Fee = Contract Size × Trade Price × Fee Rate
  • Maker = 0.02%
  • Taker = 0.06%
Example: BTC coin-margined, Size 0.1 BTC, Trade Price 60,000 USDT, Taker 0.06%: Fee = 0.1 × 60000 × 0.0006 / 60000 = 0.00006 BTC
 

2. USDT-Margined Contracts

Fee = Position Notional × Fee Rate
  • Position Notional = Position Size × Trade Price
  • Fee denominated in USDT
Example: USDT-margined, Position Size 0.1 BTC, Trade Price 60,000 USDT, Taker 0.06%: Fee = (0.1 × 60000) × 0.0006 = 3.6 USDT
 

Forced Liquidation

Margin Ratio = Account Equity / (Maintenance Margin + Transaction Fee)
  • Forced liquidation triggers when Margin Ratio ≤ 100%
  • Maintenance Margin = Position Notional × Maintenance Margin Rate
The system will attempt partial liquidation first; if insufficient, a full liquidation occurs. Remaining balance is returned to the account, and negative balances are covered by the insurance fund. Auto-Deleveraging (ADL) may apply in extreme cases.
 

FAQ

Q1: Will Coin-Margined PnL be affected by coin price? What about USDT-Margined PnL? 
A: Yes, PnL in Coin-Margined contracts is denominated in the base coin, so coin price changes affect both PnL and account equity. For USDT-Margined contracts, PnL is denominated in USDT, and once positions are closed, the realized PnL is fixed and no longer affected by market fluctuations.
 
Q2: Does USDT-Margined margin fluctuate with coin price? What about Coin-Margined margin
A: No, USDT-Margined margin is in USDT, so coin price changes only affect PnL, not margin value. Coin-Margined margin is affected by coin price: as the coin price rises, the required margin decreases; when the coin price falls, the required margin increases.
 
Q3: How is trading fee calculated? 
A: First, calculate the position notional (position value), then apply the fee rate. Coin-Margined fees are denominated in the base coin, while USDT-Margined fees are in USDT. Rates differ for Maker and Taker orders.
 
Q4: Are there any other significant differences between Coin-Margined and USDT-Margined contracts? 
A: The most notable difference is the unit of calculation: Coin-Margined uses the base coin, while USDT-Margined uses USDT. This affects calculation of trading fees, PnL, and funding fees, so careful attention is required when calculating.
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