Does anybody know where to get something what could calculate forward volatility? With forward volatility i mean what should become the implied volatility over a period of time in the future, knowing volatility from now to TIME1, and knowing volatility from now to TIME2. Then what should be the volatility from TIME1 to TIME2? or in other words: Imagine jan04 trading at 60% and apr04 at 50%, what should apr04 be trading when reaching jan04, (imagining jan04 will stay on vol 60% until expiration) Then what should now be the volatility of april04? it should be lower then 50%, but how much? This is an important instrument for evaluation optionprices, specially when there are differences in volatility over different periods.