ES margin at IB

I want to add more leverage to my positions, but I want to be precise about it.

How is margin for ES calculated at IB?

Can someone post the formula?

Thanks

 

http://www.interactivebrokers.com/index.html?html/tws/demo2.html~top.body

should have the precise info you need

 

http://www.interactivebrokers.com/html/marginRequirements/index.html might be a better link

 

Thanks much.

 

Another useful feature is the "check margin" function.

Enter the order in TWS and click "Accept" - NOT TRANSMIT.

Once the order appears in the window, right click on it, then select "check margin" and your effective new margin will be displayed as if the order were executed.

This is very helpful when deciding to turn naked writes into spreads...to see how far out you should buy (and how many) in order to free up more margin.