Mild cases take months; complex cases take 18 to 24 months, about the same as braces.
The AAO describes the mechanics: each aligner is worn about a week, at least 22 hours a day, moving teeth a fraction of a millimeter at a time, so your tray count is your timeline. NHS inform says orthodontic treatment usually delivers good results within 18 to 24 months when appliances are worn as instructed. Setup adds weeks before you start: scanning, planning, manufacturing, and fitting attachments. Compliance is the swing factor, since trays out of your mouth move nothing. Retainers after treatment are not optional if you want the result to stay.
What to do
Common questions
How long does Invisalign take?
Anywhere from a few months for small corrections to around 18 to 24 months for complex cases, and the honest answer is that aligners are not automatically faster than braces. The American Association of Orthodontists explains how the system works: each custom tray is typically worn for about a week, at least 22 hours a day, moving teeth a fraction of a millimeter at a time, and the total number of trays sets the total time. NHS inform puts typical orthodontic treatment at 18 to 24 months for good results, and that range applies to aligners doing serious work too. The biggest controllable factor is wear time: trays only move teeth while they are in, so patients who take them out for long meals and forget them stretch the timeline. Add front-loading time as well: scans, attachments, and manufacturing add several weeks before tray one. After the last tray, a retainer keeps the result, because teeth drift back without one. The realistic move: ask your provider for the projected tray count, since that converts directly into weeks.