To calculate the required margin, use the following formula:
Volume in lots × Contract size × Market price × Margin ratio
For example, when selling 1 lot of the S&P 500 index with a contract size of 1, a price of 5671.0, and a margin ratio of 1%, the margin is calculated as follows:
1 lot × 1 × 5671.0 × 1% = 56.71 USD