kB/s to Mbps converter (and Mbps to kB/s)

Reading a kB/s download: connection or source?

Kilobytes per second shows up when a transfer is slow: browser download lists while a file trickles in, torrent clients reporting per-peer speeds, older download managers, and phone apps on a weak signal. Converting the reading tells you quickly whether your line or the other end is the limit.

• A slow browser download. The window shows 850 kB/s on a 100 Mbps plan. 850 × 8 ÷ 1,000 = 6.8 Mbps, under 7% of the plan. The server or a busy route is the likely limit, not your line.
• A torrent client. Total download reads 2,500 kB/s. That is 20 Mbps, with each peer contributing a slice of it.
• Mobile data. An app update crawls at 120 kB/s: just 0.96 Mbps.

If a converted figure is far below your plan on every download, compare a wired speed test with the plan in the speed test checker.

What a slow plan looks like in kB/s

On slower connections the number in a download window looks nothing like the speed on the bill. Multiplying Mbps by 125 gives the ceiling:

• 10 Mbps line. Up to 1,250 kB/s. After protocol overhead, 1,100–1,200 kB/s is normal.
• 5 Mbps rural or satellite service. Up to 625 kB/s, so a 100 MB update needs at least 160 seconds.
• 2 Mbps mobile connection. Up to 250 kB/s; seeing 240 kB/s means the connection is almost fully used.
• 0.5 Mbps throttled plan. After a mobile data allowance runs out, about 62.5 kB/s at best.

For a finish time rather than a rate, the download time calculator takes any size and speed.

KB, kB, KiB and kbps

Apps write this unit as KB/s, kB/s or KiB/s, and they do not all mean the same thing. The decimal kilobyte (kB) is 1,000 bytes; the binary kibibyte (KiB) is 1,024 bytes, and some software counts in 1,024s but still prints "KB". 1,000 kB/s is 8 Mbps while 1,000 KiB/s is 8.192 Mbps, and 1 Mbps is 125 kB/s but about 122.07 KiB/s. If your app's documentation says it uses binary units, pick KiB/s in the converter above.

Watch the case of the b too. A reading in kbps (kilobits) needs no ×8 step at all; use kbps to Mbps. Rate limits in some tools expect raw bytes per second, which Mbps to bytes per second produces, and for sizes rather than speeds, bits to bytes applies the same factor of 8. Once readings pass 1,000 kB/s, Mbps to MB/s is easier to read, and the bytes to Mbps converter shows every unit side by side.