How long is a game of Wavelength? For most groups, the safest answer is 30 minutes. The official CMYK product page describes Wavelength as a social guessing game where two teams compete to read each other's minds, while major board-game listings commonly show a 30 to 45 minute play time. In real play, that range is accurate for a standard two-team game with several rounds, a little table talk, and a group that understands the Psychic role.
If you are hosting Wavelength online, the game can be shorter because setup is instant and the board is already on screen. If everyone is new, add five minutes for the first rules explanation. If your group loves debating, add ten minutes. If this is a classroom, work icebreaker, or party warmup, use a fixed round count instead of playing until a score target.