The speed of your transfer medium
8 bits in a byte
1024 bytes in a kilobyte
1024 kilobytes in a megabyte
1024 megabytes in a gigabyte
1024 gigabytes in a terabyte
bs = bit per second
Bs = Byte per second
Notice the prefix kilo, mega, giga, and tera differences are multiples of 1024 on the previous value.
MBps = Megabyte per second
Mbps = Megabit per second.
Common Apple Mac transfer speeds are listed below:
Airport original 802.11b is 11 Mbps
USB 1.1 12 Mbps top speed
Airport extreme 802.11g is 33 Mbps first capable of WPA2 encryption
10/100 Ethernet up to 100 Mbps
WiFi 802.11n, ac are mostly around 100 to 300 Mbps, though shared connections can be slower. First available
to 2006 and later Macs.
Apple's Firewire 400 is about 400 Mbps (IEEE 1394a 6 pin configuration in all Macs with Firewire before the 2003, 4 pin in Sony Camcorders do not pass power from the hosting computer) was mixed with 9 pin Firewire 800 on later models.
Was not bootable on Desktop Beige, Blue and White G3 Macs, or earlier PCI graphics card G4 Macs.
Apple's Firewire 800 is about 800 Mbps (IEEE 1394b)
Apple's USB 2 is 360-480 Mbps was generally not bootable on Mac OS X until Intel Macs in 2006.
Gigabite Ethernet is up to 1000 Mbps (SANs use ethernet, and so do network file shares).
Thunderbolt 2 Mid-2011 and later Macs had Thunderbolt 1 at 10 Gbps (about 10,000 Mbps) or about 1.125 GBps. Not to be confused with the similar shaped mini-Displayport ports on older Macs. A lightningbolt indicated data support though mini-Displayport could be used to connect displays in Thunderbolt 1 and 2 devices directly.
USB 3 is up to 500 MBps or 4000 Mbps. Adopted in mid-2012. Shapes the same as USB-2 on the computer side except for the blue internal fiberglass that is etched with metal.
As you can see above, the connector that goes into the computer is rectangular, but the connector that is more square some hard drive docking stations supporting USB-3.0. If the color inside the metal is not blue but shaped the same it likely is either USB 2 or 1.1.
Late 2013 and later Macs had Thunderbolt 2 at 20 Gbps per second
Above is an example of thunderbolt 2 and 1.1 cables.
2016 and later Macs used USB-C/3.1 which was effectively also Thunderbolt 3 at 40 Gbps. Apple makes USB-C to Thunderbolt 2 adapters, as well as Thunderbolt 2 to Firewire 800 adapters. External displays and hard drives do not use the power cord provided with laptops that look similar. A lightning bolt label indicated support for additional data and video technologies. The power cord could be used on pass through hubs that included two USB-C ports and one USB-C connecting cable 100W is helpful for best compatibility on these hubs. Examples of hubs that support this are:
https://www.smklink.com/products/usb-c-multi-port-hub
https://www.siig.com/catalogsearch/result/?q=JU-DK0F11-S1
(tested by author of this tip)
Cables of USB-C are not be confused for Micro-USB or Lightning
Above are lightning on left (used on most iPhones and iPads except the earliest models), and USB-C (used on most current iPads) on right. USB-C has been the standard for all current Macs as of this tip writing.
Micro-USB used on older Droid phones. Newer ones used USB-C.
Most USB Flash drives are USB-2. There are a few that are USB-3. And some even that have a flip over USB 3.1/C.
Formatting and use by background processes like Time Machine may slow it down a lot. Keep in mind all storage works best if less than 85% full. The reported speed is frequently inaccurate, as large files are easier to transfer faster than many small files, especially when the block they fill on the bytes is smaller than the actual block size of storage.
The real slowdown is anything that is external mediums.
Except for SCSI, all of Apple's data interfaces have been serial. This has resulted in sharing bus hits of speed. Multiple devices sharing the same bus according to the system profiler will each take an equal chunk of bandwidth out. The slowest device on the bus will bring the whole bus speed down with it. Using a USB keyboard or mouse frequently brings you down to the 18 Mbps speed of USB 1.1 if sharing the same bus!
