Mbps vs MB/s: Why Your Downloads Look Slower Than Your Internet Plan

You pay for a 100 Mbps connection, start a big download, and your browser shows 11 or 12 MB/s. It's a common source of frustration, but usually nothing is wrong. The two numbers are measured in different units.

Bits vs bytes

Internet plans are sold in megabits per second (Mbps, with a small "b"). Browsers, download managers and app stores usually show megabytes per second (MB/s, with a capital "B"). A byte is 8 bits, so divide by 8: 100 Mbps is a maximum of 12.5 MB/s, and 50 Mbps is about 6.25 MB/s.

How long will a download take?

A 5 GB game update is about 40,000 megabits. At a perfect 100 Mbps, that takes 400 seconds, just under seven minutes. In practice, add some extra time for the overheads described below.

Why real speed is a bit lower

• Network protocols use part of the bandwidth to manage the connection, so even a perfect wired connection delivers somewhat less than the advertised number.
• The server you're downloading from may be slower than your connection.
• Other devices at home, phones updating apps, smart TVs streaming, share the same connection.

Wi-Fi is usually the real bottleneck

If wired speed is fine but Wi-Fi is slow, the router is often the limit. The 2.4 GHz band reaches further through walls but is slower and more crowded; the 5 GHz band is much faster but has shorter range. Walls, floors and distance all reduce speed. Moving closer to the router, using 5 GHz, or placing the router centrally and in the open often helps more than upgrading your plan.

Testing your speed properly

For the most accurate result, test with a device connected by cable, or standing near the router on 5 GHz, with other devices idle. Run the test a few times at different times of day, since networks are busier in the evening.

Storage sizes add one more twist

Network speeds use decimal units: 1 megabit is exactly 1,000,000 bits. File sizes on computers are often shown in 1,024-based units, which is also why a "1 TB" drive appears as about 931 GB on your computer.

Try it: the Data Speed Converter converts between Mbps and MB/s instantly, and the Data Storage Converter handles file sizes.

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