Recently, a friend asked me about margin in contract trading, so I organized my understanding and, at the same time, explained the differences between full position and isolated margin modes.

First of all, it’s important to clarify that in contract trading, margin consists of two concepts. The amount required to open a position is called initial margin, and the minimum amount needed to maintain the position afterward is called maintenance margin. These two concepts are important because they directly affect your risk management.

When it comes to risk management, you have to talk about the two modes: full position and isolated margin. I’ll start with full position. In the full position mode, all available balances in your contract account can be used as margin. Suppose your position incurs a loss; the system will automatically add margin from your available balance until it reaches the level of the initial margin. But if, after all available balances have been topped up, you still can’t meet the maintenance margin requirement, the system will stop adding margin and execute a forced liquidation. In this mode, the risk and profit/loss of multiple positions are calculated together—that is, as long as the contract account still has remaining balance, the positions have a chance to survive.

Isolated margin is completely different. In this mode, the margin for each position is independent, and the system will not automatically add margin. If you want to add margin, you must do it manually yourself. When a position can’t reach the maintenance margin level, the system will liquidate it directly; however, your loss is limited to this position’s margin and will not affect the other funds in your account.

Let me use a practical example to make it easier to understand. Suppose users A and B both have 2000U in their contract accounts, and each uses 1000U to open a 10x leveraged long position on BTC/USDT. A chooses the isolated margin mode, while B chooses the full position mode. If the BTC price drops to the liquidation price, A will lose the 1000U margin and be liquidated, leaving 1000U in the account. But B, using full position mode, will have margin added automatically, and the position remains open. At that point, if BTC rebounds, B has a chance to turn losses into profits; but if BTC continues to fall, B’s entire 2000U could be wiped out.

From the perspective of advantages, full position mode has stronger loss-absorption capability, and it’s also less likely to lead to liquidation in low-leverage and choppy market conditions. The downside is that once you encounter a major market move or a sudden event, it can easily cause the entire account to go to zero. Isolated margin provides you with more risk isolation, but you need to actively manage your margin, and you must strictly control the distance between the liquidation price and the mark price—otherwise, a single position can easily get liquidated.

As for calculations, the formula for position margin is as follows: position margin equals opening value divided by leverage plus manually added margin minus reduced margin plus unrealized profit and loss. The liquidation risk is calculated based on the ratio between position margin and maintenance margin. For isolated margin, liquidation risk equals (maintenance margin divided by position margin) times 100%. For full position, liquidation risk equals (maintenance margin divided by available balance plus position margin) times 100%. When risk reaches 70%, the platform usually issues a warning; when it exceeds 100%, liquidation is triggered.

Most mainstream contract trading platforms default to full position mode for users, and both modes support adjusting leverage. The maximum leverage is typically up to 100x. However, one detail to pay attention to is that when you have open orders, you cannot switch between full position and isolated margin modes, and you also can’t change your leverage—so the order of your operations is important.

In summary, full position is suitable for experienced traders who want to make better use of capital efficiency; isolated margin is more suitable for risk-averse traders because it can effectively isolate risk. The key is still to choose based on your trading style and risk tolerance.