Clear Calculators

Internet guide

Mbps vs MB/s explained

Broadband speeds, file sizes and app download rates often use similar-looking labels. The important difference is bits versus bytes.

Short version: Mbps means megabits per second. MB/s means megabytes per second. There are 8 bits in 1 byte, so 100 Mbps is about 12.5 MB/s before real-world slowdowns.

Why broadband speed is usually shown in Mbps

Internet providers usually advertise speeds in bits per second. A lowercase b means bits, so Mbps means megabits per second. File managers and browsers often show bytes instead. An uppercase B means bytes, so MB/s means megabytes per second.

That one letter matters. If a game is 75 GB and your line is 100 Mbps, the simple estimate is not 75 divided by 100. The file size is in bytes, while the line speed is in bits.

The simple conversion

Bits to bytes

Divide by 8. A 100 Mbps line is about 12.5 MB/s before overhead.

Bytes to bits

Multiply by 8. A 5 GB file is about 40 gigabits in decimal units.

Real-world speed

Wi-Fi, server limits, VPNs, other devices and protocol overhead can reduce the usable rate.

GB and GiB can also differ

GB usually means decimal gigabytes: 1 GB is 1,000,000,000 bytes. GiB means binary gibibytes: 1 GiB is 1,073,741,824 bytes. Storage devices, operating systems and apps do not always use the same display style, so the same drive or file can look slightly different in different places.

How this affects download and usage estimates

  • Download time depends on file size, usable speed and whether the server can keep up.
  • Monthly broadband use depends more on what you do than on headline speed.
  • Streaming video usually uses much more data than web browsing or online gaming sessions.
  • Large game downloads, system updates and cloud backups can create one-off spikes.

Useful tools

Estimate download time Estimate monthly usage Check storage space Convert data rates

This guide is general information only. Internet speed, storage display and data usage can vary by provider, device, app settings, file compression and network conditions.

Why the difference matters

Broadband speeds are normally sold in Mbps, meaning megabits per second. File sizes are normally shown in MB or GB, meaning megabytes or gigabytes. Because there are 8 bits in a byte, a 100 Mbps line has a theoretical maximum of about 12.5 MB/s before real-world overheads.

This distinction affects download estimates, cloud backups, game updates and broadband usage planning. If a download calculator result looks eight times larger or smaller than expected, Mbps and MB/s are the first units to check.