USB 2.0 vs. USB 3.0

USB 2.0
USB 3.0

USB 3.0 is the improved version of USB (Universal Serial Bus) that provides better speed and more efficient power management than USB 2.0. USB 3.0 is backward compatible with USB 2.0 devices; however, data transfer speeds are limited to USB 2.0 levels when these devices inter-operate. In 2014, a new standard, USB 3.1, was released and is expected to be in widespread use by 2015.

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USB 2.0

User Rating (197):
USB 2.0

USB 3.0

User Rating (239):
USB 3.0
Released April 2000 November 2008
Speed High Speed or HS, 480 Mbps (Megabits per second) 10 times faster than USB 2.0. Super Speed or SS, 4.8 Gbps (Giga bits per second)
Signaling Method Polling mechanism i.e can either send or receive data (Half duplex) Asynchronous mechanism i.e. can send and receive data simultaneously (Full duplex)
Price For a similar product, the USB 2.0 version is generally less expensive than it's USB 3.0 version. For a similar product, the USB 3.0 version is generally more expensive than it's USB 2.0 version.
Power Usage Up to 500 mA Up to 900 mA. Allows better power efficiency with less power for idle states. Can power more devices from one hub.
Number of wires within the cable 4 9
Standard-A Connectors Grey in color Blue in color
Standard-B Connectors Smaller in size Extra space for more wires
Max Cable length 5 meters 3 meters

Contents: USB 2.0 vs USB 3.0

edit What is USB 3.0 and USB 2.0?

A USB 3.0 Memory Stick
A USB 3.0 Memory Stick

Developed in the 1990s, the Universal Serial Bus (USB) standard was developed to define communication protocols, including cables and connectors, between computers and electronic devices such as printers and scanners. As the number of devices multiplied in quantity and types, the USB port was adopted as the basic connection portal.

Devices like smartphones, PDAs, tablets, smartphones and video game consoles can connect to computers with USB ports allowing recharging and communication thereby replacing the requirement of adapters and power chargers.

USB3.0 was released in November 2008, almost eight years after the release of USB 2.0. Over five years later, in 2014, USB 3.1 was released with widespread use expected in 2015.

edit What is USB 3.1?

The newest standard is for USBs is USB 3.1. It offers three major improvements over 3.0: an "always right" C-type connector that plugs in without regard to orientation, higher data transfer speeds of up to 10 gigabytes per second, and the capacity to power any type of device.

The C-type connector is small enough for modern, slim devices, such as MacBook Air-type notebooks, tablets, and smartphones. but still robust enough for 10,000 cycles of use. Data transfer speeds are more in sync with current app and user needs, especially for video and image files. And the option to connect to and power any type of device, with 100 watts of charging power that can be divided between two devices, greatly reduces "charger and cable clutter," simplifying connectivity between personal devices. However, backwards compatibility will be limited.

edit USB 3.0 Highlights and Benefits over USB 2.0

When data is being transferred through USB 3.0 devices, cables, and connectors, the transaction is initiated by the host making a request followed by a response from the device. The device either accepts the request or rejects it. If accepted, the device sends data or accepts data from the host. If there is lack of buffer space or data, it responds with a Not Ready (NRDY) signal to tell the host that it is not able to process the request. When the device is ready then, it will send an Endpoint Ready (ERDY) to the host which will then reschedule the transaction.

edit Physical Differences

USB 3.0 Connectors are different from USB 2.0 Connectors and the 3.0 connectors are usually colored blue on the inside in order to distinguish them from the 2.0 connectors.

Various types of USB Connectors (click to enlarge). From Left to Right: Micro USB Type AB, Micro USB Type B, USB 2.0 Type A, USB 2.0 Type B, USB 3.0 Type A, USB 3.0 Type B, USB 3.0 Type Micro B, Min USB Type A connector
Various types of USB Connectors (click to enlarge). From Left to Right: Micro USB Type AB, Micro USB Type B, USB 2.0 Type A, USB 2.0 Type B, USB 3.0 Type A, USB 3.0 Type B, USB 3.0 Type Micro B, Min USB Type A connector

edit Backward Compatible

USB 3.0 is compatible with USB 2.0. However, the USB 3.0 product will perform at the same level as a USB 2.0 product, so speed and power benefits will not be fully realized.

USB 3.0 receptacles are electrically compatible with USB Standard 2.0 device plugs if they physically match. USB 3.0 type-A plugs and receptacles are completely backward compatible, and USB 3.0 type-B receptacles will accept USB 2.0 and earlier plugs. However, USB 3.0 type-B plugs will not fit into USB 2.0 and earlier receptacles.

This means that USB 3.0 cables cannot be used with USB 2.0 and USB 1.1 peripherals, although USB 2.0 cables can be used with USB 3.0 devices, if at USB 2.0 speeds.

The following videos review the speed of USB 2.0 vs USB 3.0 products:

edit Price

For a similar product, the USB 3.0 version is generally more expensive than its USB 2.0 version.

You can check the current prices on Amazon for a few USB 2.0 vs USB 3.0 enabled devices:

edit References

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Comments: USB 2.0 vs USB 3.0

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Anonymous comments (7)

March 1, 2014, 10:13am

Thank you

— 94.✗.✗.147
4

July 17, 2013, 1:41pm

On a SERIAL connection, such as USB, it is "bits" that are transferred, not "bytes". Thus, the terminology of bps, not Bps, is appropriate, and honest. Congrats and thanks to the presenter for a great tutorial and demo of USB 3.0 and 2.0.

— 65.✗.✗.200
4

October 27, 2013, 1:50pm

excellent information

— 108.✗.✗.188
2

June 28, 2013, 1:50am

Great information. Thank you!

— 64.✗.✗.90
2

December 6, 2013, 8:53pm

Tanks for splaining

— 71.✗.✗.168
0

June 5, 2013, 5:08am

I really wish that the manufacturers would switch from Mbps to MBps! We passed the bits data transfer level back in the 90's but I guess they're still fooling people with the small "b" instead of the capital "B"! It's like making something $1.99 to keep it under $2! Ahhhhhhh...psychology and the easily tricked human mind! Seriously...when are we going to move up the terminology!

— 37.✗.✗.154
-1

July 29, 2013, 12:05am

The first anonymous commenter is completely wrong. Today, everything is in "bps" because everything today is being communicated via high-speed serial links. This began with USB1 and the old Firewire. This has become the single most important change in the way things are done across the whole spectrum, as we see in such things as PCI Express, which is the old PCI bus implemented as an array of high-speed serial links.

— 220.✗.✗.153
-2

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