A wide variety of different sized MATs exist around the country from 2 up to over 50 constituent academies. Either extreme of size can be made to work with the right leadership, ethos and approach. However there is growing evidence that there is a minimum viable size for a MAT of 1200 pupils (regardless of number of schools) in order to keep overheads at a manageable rate. Larger sizes of 10,000 students are increasingly beiing encouraged by school comissioners - particularly for secondary school MATs.
The majority of MATs are currently made up of less than 5 academies but the trend is towards somewhat larger sizes. If MATs are too small they fail to offer the cost saving benefits that come with scale. However, maintaining good oversight, governance and leadership of all schools within a very large MAT can be a considerable challenge.
Another factor to consider along with ultimate size is the rate of growth – rapid growth is very hard to manage successfully and some of the best regarded MATs have grown steadily over time.