Opinions vary according to different experts. Jack Callagha, professor in Waterloo’s Department of Kinesiology, has found that the ideal sit-stand ratio lies between 1:1 and 1:3.  Kevin Weaver, clinical assistant professor at New York University, suggests you should aim to stand for about 4 hours a day, sit for another 4 and switch every hour.  Chris Kolba, sports medicine physical therapist at Ohio State University, says you should aim to stand for as long as you can until you get tired.