Internet speed

What is the difference between Mbps and MBps?

One capital letter changes the number by a factor of eight, which is why a 100 Mbps plan never downloads at 100 MB a second.

Mbps is megabits per second and MBps is megabytes per second, and one byte is eight bits — so MBps is eight times larger. Broadband is always advertised in the smaller unit because it produces a bigger number. A 100 Mbps connection downloads at about 12.5 MB per second; a 40 Mbps connection at 5 MB per second. To convert an advertised speed into real download speed, divide by 8.

Worked out 2026-09-10 (IST) · 1 byte = 8 bits; ISP speeds quoted in decimal megabits

Advertised speed against real download speed

Divide by 8. The right-hand columns are how long that connection takes on files people actually download.

Connection speed converted, and time to download
Plan (Mbps)	Real speed (MB/s)	100 MB file	1 GB file	5 GB game	50 GB game
10	1.25	80 s	13.3 min	66.7 min	11.1 h
20	2.50	40 s	6.7 min	33.3 min	5.6 h
40	5.00	20 s	3.3 min	16.7 min	2.8 h
50	6.25	16 s	2.7 min	13.3 min	2.2 h
100	12.50	8 s	1.3 min	6.7 min	1.1 h
150	18.75	5 s	0.9 min	4.4 min	0.7 h
200	25.00	4 s	0.7 min	3.3 min	0.6 h
300	37.50	3 s	0.4 min	2.2 min	0.4 h
500	62.50	2 s	0.3 min	1.3 min	0.2 h
1000	125.00	1 s	0.1 min	0.7 min	0.1 h

These are ceilings, not promises. The table assumes the connection runs at its full line rate and the server on the other end can keep up. In practice expect 80–95 per cent of these figures on a wired connection and considerably less over Wi-Fi.

Every unit, spelled out

Bits and bytes
Written	Says	Means	In bytes per second
1 Kbps	kilobit per second	1,000 bits/s	125 B/s
1 KBps	kilobyte per second	8,000 bits/s	1,000 B/s
1 Mbps	megabit per second	1,000,000 bits/s	125 KB/s
1 MBps	megabyte per second	8,000,000 bits/s	1 MB/s
1 Gbps	gigabit per second	1,000,000,000 bits/s	125 MB/s

The formula

Mbps → MB/s = Mbps ÷ 8

MB/s → Mbps = MB/s × 8

download time in seconds = file size in MB × 8 ÷ speed in Mbps

Check your own numbers

Convert bits, bytes and their multiples in either direction.

Data Storage ConverterBits to bytes, KB, MB, GB and TB, in binary and decimal.

Frequently asked

Why do ISPs advertise in Mbps instead of MBps?

Because the number is eight times larger for the same connection. "300 Mbps" reads better than "37.5 MBps". It is also the historical convention: network engineers have measured line rate in bits per second since long before consumer broadband existed, so the unit is genuine, not invented for marketing - it is just the one that flatters.

Am I getting the speed I pay for?

Run a speed test and multiply your download figure in MB/s by 8 to compare it with the plan. On a wired connection you should see 80 to 95 per cent of the advertised rate; overheads in TCP/IP and the physical layer account for the rest. Over Wi-Fi, especially on 2.4 GHz or more than one wall away from the router, half the advertised rate is common and is a Wi-Fi problem, not an ISP problem.

What about Kbps, Gbps and mbps?

Kbps is kilobits per second (1,000 bits) and Gbps is gigabits per second (1,000,000,000 bits). A lowercase "mbps" is technically millibits per second and is always a typo for Mbps. The capital B is the only thing that means bytes: Kb is kilobits, KB is kilobytes.

How much speed do I need to stream 4K?

Netflix recommends 15 Mbps for 4K, YouTube about 20 Mbps, and a 4K Blu-ray-quality stream can want 25 Mbps. That is 1.9 to 3.1 MB per second. A 100 Mbps line therefore supports three or four simultaneous 4K streams comfortably, which is usually the real reason to buy more than 50 Mbps rather than faster single downloads.

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