# Size | Quantity | Value

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Note: Coin-margined futures contract is a reverse contract, and it is difficult to understand the parameters. Please refer to [USDⓈ-Margined Futures | Coin-Margined Futures](https://futuresdoc.gitbook.io/perp-doc/english-1/parameters/usds-margined-or-coin-margined-futures-contracts).
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## Contract Size | Order Quantity

The contract size is also called Lot Size, which is the smallest unit of the contract transaction quantity, that is, the quantity of a contract.

The relationship between contract size and quantity is as follows:

<table><thead><tr><th width="142"> </th><th width="106">Order Cont.</th><th width="143">Contract Size</th><th width="138">Order Quantity</th><th>Quantity, Size Unit</th></tr></thead><tbody><tr><td>USDⓈ-Margined Futures</td><td>2</td><td>1 Cont. = 0.0001 BTC</td><td>0.0002 BTC</td><td>Always match the underlying currency</td></tr><tr><td>Coin-Margined Futures</td><td>2</td><td>1 Cont. = 1 USD</td><td>2 USD</td><td>Always match the quote currency</td></tr></tbody></table>

### Why is the quantity of coin-margined futures in USD?

This is related to the mechanism of the reverse contract, please see [How to understand the reverse contract](https://futuresdoc.gitbook.io/perp-doc/english-1/usds-margined-or-coin-margined-futures-contracts#a-way-of-understanding-reverse-contracts).

#### Is this different from what I've seen on other exchanges?

You can use BTC as a unit to open positions on exchanges such as Binance, okx, etc., but you will find that as the price of BTC changes, the amount of BTC in your position is also changing. But you will find that as the price of BTC changes, the amount of BTC in your position is also changing. This is because coin-margined futures are all measured by 1 cont. = 1 USD and only the price conversion is performed when placing an order or displaying a position. You can switch the unit to ‘Cont.' and you will find that the number of positions will not change, that is to say, the real number of positions in USD.

## Order value | Position value

### Calculation of values

<table><thead><tr><th width="148"> </th><th>Order Value</th><th>Position Value</th><th>Unit</th></tr></thead><tbody><tr><td>Coin-Margined Futures</td><td>= Cont. * size * order value</td><td>= Cont. * size * mark price</td><td>Quote currency （USDT）</td></tr><tr><td>USDⓈ-Margined Futures</td><td>= Cont. * size / order value</td><td>= Cont. * size / mark price</td><td>Underlying currency （BTC）</td></tr></tbody></table>

### Unit of values

The value unit of USDⓈ-margined futures is the quote currency, which is easy to understand. The most difficult thing to understand about a coin-margined futures contract is the value because its underlying currency and pricing currency are reversed. You can refer to [how to understand the reverse contract](https://futuresdoc.gitbook.io/perp-doc/english-1/usds-margined-or-coin-margined-futures-contracts#a-way-of-understanding-reverse-contracts).

<table><thead><tr><th width="203"> </th><th width="221">Quantity Unit</th><th>Value Unit</th></tr></thead><tbody><tr><td>USDⓈ-Margined Futures</td><td>Underlying currency (BTC)</td><td>Quote currency (USDT)</td></tr><tr><td>Coin-Margined Futures</td><td>Quote currency (USDT)</td><td>Underlying currency (BTC)</td></tr></tbody></table>

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The quantity and value of USDⓈ-margined and coin-margined futures are reversed.
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