Minimum size for Batch Apex in Salesforce is 1.

Maximum size for Batch Apex in Salesforce is 2000.

To know more about Batch Apex in Salesforce, check the below link

https://www.infallibletechie.com/2012/05/batch-apex.html

Note:


1. Default is 200.

2. If you specify the batch size more than 2000, it will consider as 2000.

Cheers!!!