Mbps vs MB/s Explained: How Long Will My Download Take?

You pay for a “100 Mbps” broadband plan, start a download and see 12 MB/s. Are you being short-changed? Almost certainly not — you are looking at two different units. This guide explains the difference in plain English and shows how long common downloads really take.

Bits vs bytes

Computers count data in bits and bytes. One byte is made of eight bits.

• Mbps (lowercase *b*) means megabits per second. Internet providers and speed tests use it.
• MB/s or MBps (uppercase *B*) means megabytes per second. Browsers, download managers and file sizes usually use it.

So to convert, divide by 8:

• 8 Mbps = 1 MB/s
• 100 Mbps ≈ 12.5 MB/s
• 1 Gbps (1,000 Mbps) ≈ 125 MB/s

Quick conversion table

In practice, downloads usually run 5–15% below these figures because of network overhead, Wi-Fi and the speed of the server you are downloading from.

How long will my download take?

The formula is simple: time = file size in megabits ÷ speed in Mbps. Multiply the size in MB by 8 to get megabits. Here are ideal times for common files (real downloads may take a little longer):

The difference is striking: a 50 GB game takes over 11 hours on a 10 Mbps connection, but under 7 minutes on full-fibre gigabit.

What about upload speed?

The same maths applies to upload. If your connection has 20 Mbps upload, sending a 1 GB video to a client takes about 400 seconds — just under 7 minutes. Many plans have much slower upload than download, so check both before choosing a plan if you share large files, back up to the cloud or create content.

Check your real speed

Your plan’s number is the maximum, not a guarantee. Run our free internet speed test to see your actual download and upload in Mbps, then divide by 8 to estimate your real-world download rate in MB/s. If results are far below your plan, read our guide on fixing slow internet.

Frequently asked questions

Is Mbps the same as MB/s?

No. Mbps means megabits per second, while MB/s means megabytes per second. One byte is eight bits, so 100 Mbps is about 12.5 MB/s.

Why is my download speed in MB/s lower than my plan in Mbps?

Your plan is advertised in megabits, but browsers and download managers usually show megabytes. Divide your plan by 8: a 100 Mbps plan downloads at roughly 12.5 MB/s at best, and a little less in practice because of network overhead.

How many Mbps is 1 Gbps?

1 Gbps (gigabit per second) equals 1,000 Mbps, which is up to about 125 MB/s.

How long does it take to download 1 GB at 100 Mbps?

In ideal conditions, about 80 seconds: 1 GB is 8,000 megabits, and 8,000 ÷ 100 = 80 seconds. Real downloads are usually 5–15% slower.

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