You could use GNU units. It appears to treat SI prefixes as strictly base 10,
so use the KiB/MiB etc. variants where applicable:
> $ units 8112116KiB MiB
> * 7921.9883
> / 0.00012623094
Something like
> …2>&1| awk '/transferred/' {print $1}'|while read i; do units "${i}bytes" "GiB"; done
That will need playing around with.