Data transfer rate converter

Internet providers advertise speeds in bits per second (Mbps), but browsers and download managers show progress in bytes per second (MB/s). The factor of 8 between them, plus decimal and binary prefixes, makes comparisons confusing. This converter translates between all common data rate units.

How to use it

1. Enter a rate and choose its unit.
2. Read the equivalent rates in bits and bytes per second.

Key relationships

• 1 byte = 8 bits, so MB/s = Mbps / 8.
• 1 Mbps = 1,000,000 bits per second (networking uses decimal prefixes).
• 1 Gbps = 1,000 Mbps = 125 MB/s.

Real-world examples

• A 100 Mbps broadband line gives at most 12.5 MB/s. In practice, protocol overhead and Wi-Fi reduce that to roughly 10 to 11.5 MB/s.
• Gigabit Ethernet (1 Gbps) tops out at about 117 MB/s of usable throughput.
• USB 3.0 is rated at 5 Gbps, or 625 MB/s raw, but real drives typically reach 100 to 450 MB/s.

Estimating download time

Time = file size / transfer rate, with both in the same unit. A 4 GB file (4,000 MB) over a 100 Mbps line (12.5 MB/s) takes 4,000 / 12.5 = 320 seconds, about 5.3 minutes at full speed. Add 10 to 20% for overhead in real life.

Notation tips

• Lowercase b means bits, uppercase B means bytes. Mbps and MBps differ by a factor of 8.
• Some tools use binary units (MiB/s), which are about 5% smaller than MB/s.