This is a daily metric for the bucket.
The amount of data in bytes stored in a bucket in the STANDARD storage class, INTELLIGENT_TIERING storage class, Standard-Infrequent Access (STANDARD_IA) storage class, OneZone-Infrequent Access (ONEZONE_IA), Reduced Redundancy Storage (RRS) class, S3 Glacier Instant Retrieval storage class, Deep Archive Storage (S3 Glacier Deep Archive) class, or S3 Glacier Flexible Retrieval (GLACIER) storage class.
This value is calculated by summing the size of all objects and metadata in the bucket (both current and noncurrent objects), including the size of all parts for all incomplete multipart uploads to the bucket.