Phrasal verbs can be difficult to understand at the best of times. In most cases there is no logic to them, or they cannot be taken literally. But for these phrasal verbs with fall, there is some logic you can apply to help you understand when and how to use them. While it may not apply to all situations, in many it can help to think of the following:
Fall off
If you are going to fall OFF something, you must first be ON something so you can fall off and drop vertically on to the floor. In the photo above, the cyclist has fallen off his bike.
For example:- I was sitting on the chair, and I fell off.
- You can fall off a bike, a ladder, a surfboard or skateboard etc
Fall down
If you are going to fall DOWN something, you must first be UP it and then fall down. This usually involves falling down something at an angle, such as stairs.
For example:- I was walking up the stairs, and I fell down them.
- You can fall down a hill
Fall over
If you are going to fall over something, it usually involves tripping over something that is below you, like a bag on the floor.
For example:- Someone left a bag on the floor and I fell over it.
- You can fall over a piece of wood, a low fence etc.
Or you can simply trip over your own feet and fall over.

Falling down the stairs
Photo: Image by Vitabelo at Pixabay:
Watch my video:
In this video I give you some visual examples to help you try to understand when and how to use these phrasal verbs with fall.
In the comments, tell me about a time you have: fallen off, down or over something.