Jiggunjer está correto
Resposta curta:
914,3 MB == 871,9 MiB
O mebibyte (MiB) foi projetado como um substituto para o Megabyte (MB) e o armazenamento em nuvem empresarial você está fazendo o upload para provavelmente o usa. Sua estação de trabalho provavelmente não, daí a conversão.
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Detalhes adicionais:
Qual é a diferença entre 1 MiB e 1 MB?
The difference between 1 KiB and 1 KB is 1024−1000 bytes. The difference between 1 GiB and 1 GB is 10243−10003 bytes.
The "ibi" (or binary prefix) units (kibi, mebi, gibi) are based on 210 (1024), where the standard decimal units (kilo, mega, giga) are based on 103 (1000). Before the MiB was in use (I remember learning about it in school, circa 2002), MB often was ambiguous - was it binary or decimal? Often storage manufacturers would advertise using decimal, since 100GB is smaller than 100GiB (100GB is actually 93GiB and some change), while internally operating systems worked in binary units (the disk size and file size was always reported in GiB). Memory (RAM) manufacturers have always been using MiB/GiB, even though labeled "MB/GB". Source