Q. How long is a Semi-Annual Channel of Windows 10 supported for?
A. 18 months from the time the channel is released, i.e. Semi-Annual Channel (Pilot) is available. Previously support cycles were based on the two most recent branches plus a 60 day grace period which was required because of the irregular release cadence. With the new semi-annual regular release cadence this is no longer necessary and a set 18 months is easier to understand (and includes the previous 60 day grace period).