1 Gb = 1,000 Mb = 1,000,000 kb = 1,000,000,000 b = 8,000,000,000 bit
Since Giga- stands for 10^9, Mega- for 10^6 and kilo- for 10^3
1 Gib = 1,024 Mib = 1,048,576 kib = 1,073,741,824 b = 8,589,934,592 bit
Since Gibi- stands for 2^30, Mebi- for 2^20 and kibi- for 2^10
So we should tecnically be calling them Gibibyte, Mebibyte and kibibyte. And remember: the unit B stands for Bel, like deciBels (dB)
So Gmail are technically using 1Gb (1,000 Mb), but they probably (rather technically) mean 1,000 Mib and thus it's "more than 1,000 Mb".
ok? good