A billion minutes of TV are viewed on PCs, mobiles and tablets each week according to new figures from BARB.
This equates to between 1-1.5 per cent of additional TV viewing on top of traditional consolidated seven day TV viewing.
Based on data from September 2017, BARB's report states 16-34 year olds account for 22 per cent of all TV viewing from computer devices, but only 15 per cent of TV set viewing.
Age profiles also change when viewing is divided by on-demand or live streaming. Viewers aged under 35 accounted for just under 40 per cent of all on-demand viewing activity in September, compared to 14 per cent of live streaming across the month.
The report also shows younger viewers will catch up on their favourite programmes at a later time while older viewers prefer to watch live.
It also found women account for 60 per cent of all viewing via broadcaster player apps in September, although Sky Go had a predominantly more male audience at 58 per cent.