The size of a cat enclosure will depend on the available space of your outdoor area.
If you are installing a portable cat enclosure, a single size enclosure 1.2m or 1.8m in size is ideal for one cat. If you have 2 or more cats, a double enclosure or triple size enclosure is best.
When considering the size of your cat enclosure, you must also importantly take into account how this space is utilised. No matter the size of the cat enclosure, remember that all cats need vertical climbing space and places to hide. Sunny areas where they can rest should also be incorporated.