How to get the correct folder size in my MacBook pro

I am a bit unclear about how to get the correct folder size in my MacBook pro.

.when I open the folder info, I get this. The title says 9.09 GB, but under general, it reads 9,088,493,473 bytes and 9.13 GB, which is actually a wrong conversion of bytes because the actual should be

#9088493473/(1024**3)
8.464319140650332 GB

Now, from the terminal when i run

** -hs my_path
8.6G	my_path

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