ucUnitCloudInternational unit matrix

Mistake guide

Confusing Mbit/s with MB/s

A 100 Mbit/s line downloads at 100 MB/s.

01Assumption

A 100 Mbit/s line downloads at 100 MB/s.

02Actually

A 100 Mbit/s line transfers 12.5 MB/s. A byte consists of eight bits, so MB/s is always a factor of eight below Mbit/s.

03Why

Providers advertise bandwidth in Mbit/s because the number looks larger there, while download tools and file managers display MB/s. Both figures are correct; they just describe different units — and both letter sequences look almost identical.

04Check

Watch the capitalisation: lower-case b means bit, upper-case B means byte. To estimate download time, divide the Mbit/s figure by eight to get MB/s. For a 1 GB file on a 100 Mbit/s line that gives 1000 MB ÷ 12.5 MB/s = 80 seconds as a theoretical lower bound.

Matching conversions

Megabit per second to Megabyte per secondMbit/s → MB/sData rateMegabyte per second to Megabit per secondMB/s → Mbit/sData rateGigabit per second to Gigabyte per secondGbit/s → GB/sData rateMegabit per second to Kilobit per secondMbit/s → kbit/sData rate

Matching tables

TableBandwidth: Mbit/s in MB/s

Unit family: Data rate

Sources

BIPM SI BrochureSI base units, prefixes and official SI context.IEC 80000-13Binary prefixes KiB, MiB, GiB, TiB against the decimal SI prefixes.
When not to use

Do not use as the sole basis for official, medical, safety-critical or contractual decisions.

Citation

Citation note: UnitCloud, mistake guide, sources reviewed: September 2026. Source basis: BIPM SI Brochure · IEC 80000-13.