What do you mean by that?
Are you asking from the organisation’s point of view or the individual’s?
Do you mean how many hours are you at your desk actively being productive, or how many hours of your life are dedicated to work meaning you can’t do anything else (including travelling, emailing and thinking)?
I bet the answers are very different.
I wonder which answer organisations want to hear. And I wonder how can organisations talk about employee health and work/life balance until they recognise the difference between the two answers?