I believe you meant that you have an internet speed of 81 MegaBytes vs 81 Megabits.

OP is confused but I’m pretty sure he’s right about that part. Most (all?) ISPs advertise service in Megabit / Gigabit speeds. Definitely here in the U.S. not sure if other countries do that differently.

Also most speedtest sites measure in Megabit / Gigabit. e.g. www.speedtest.net is a popular one and by default it measures bandwidth speeds in Megabit / Gigabit.