- 1 GiB = 1073 MB (1024 bytes ^ 3)
The docs don't seem to explicitly mention it. They just say GB.
But AWS has been known to use GB for simplicity in docs - as in https://aws.amazon.com/s3/pricing/.
I have been tearing my hair out trying to get to the bottom of this. It starts to matter when making cost calculations are large scale.
Just scroll down a bit. It's in the "S3 Pricing Details" section of that page you linked to: (https://aws.amazon.com/s3/pricing/#:~:text=Amazon%20S3%20sto....)