Every Harry Potter movie in order
To watch the Harry Potter movies in order, start with Harry Potter and the Philosopher's Stone, then Harry Potter and the Chamber of Secrets and Harry Potter and the Prisoner of Azkaban. That's 8 out so far, about 20 hours, ending with Harry Potter and the Deathly Hallows: Part 2.
Eight films, one for each year at Hogwarts, with the last book split into two. They follow straight on from each other, so watch them in order.
Updated
The Harry Potter movies in order
Harry Potter and the Philosopher's Stone
Harry Potter and the Chamber of Secrets
Harry Potter and the Prisoner of Azkaban
Harry Potter and the Goblet of Fire
Harry Potter and the Order of the Phoenix
Harry Potter and the Half-Blood Prince
Harry Potter and the Deathly Hallows: Part 1
Harry Potter and the Deathly Hallows: Part 2
Also worth watching
Harry Potter (HBO)
HBO retells the story from the start, one book per season.
Questions
What order should I watch the Harry Potter movies in?
Start with Harry Potter and the Philosopher's Stone, then Harry Potter and the Chamber of Secrets and Harry Potter and the Prisoner of Azkaban, and follow the list above: 8 in all, ending with Harry Potter and the Deathly Hallows: Part 2.
How long does it take to watch all of the Harry Potter movies?
About 20 hours for the 8 out so far.
Is it the Philosopher's Stone or the Sorcerer's Stone?
The same film. It's called the Philosopher's Stone in the UK and most of the world, and the Sorcerer's Stone in the US.
Do I need to watch the Fantastic Beasts films?
No. They're set about 70 years earlier and follow Newt Scamander and a young Dumbledore. Watch them before or after Harry Potter.
Watch the Harry Potter movies with Chronologica
Make a plan of just the Harry Potter movies, mark them off as you go and always know what's next. No account needed.