Any reasonably priced "must-have" option software?

What option software do you find indispensable? I'm looking for something user-friendly that can help me to figure out P/L, position sizing, pricing and such on the fly. Thanks!

 

Think or Swim has good software and its FREE.

 

But I don't want to move my account just for that.

 

This should keep most option traders very busy

http://hoadley.net/options/options.htm

 

Some help much appreciated.

I have an a/c with IB and mostly I trade credit spreads on index futures.

I would like to know margin used up for my different trades. IB only gives margin realtime in total but not by individual trades. If I knew margin details I would close some positions to relese margin to maximise use of my capital.

Thanks

 

What about making an excel sheet connected to IB TWS that calculates the margin.