What size sticky note is most useful?

The 3x3 inch square is the default workhorse cited most often by teachers, planners, and office reviewers. Multi-size packs (with 4x6 lined pads added) get praised by reviewers who take longer notes, while 1.5x2 mini pads are popular for tabs and flags. Specialist subreddit threads suggest buying a 3x3 multi-pack first and adding sizes only as you learn your habits.