A standard dressage arena is 20 metres by 40 metres and 8 letters are used around the edge of the arena. A long dressage arena is 20 metres by 60 metres and 12 letters are used around the edge of the arena.
The images below show the location of letters placed around 20m x 40m dressage arena and 20m x 60m dressage arena. These images show both the physical dressage markers around the edge of the arena, and the internal letters down the centre line that need to be memorised.
20m x 40m Dressage Arena Letters
20m x 60m Dressage Arena Letters