What Is USB 2.0?

R. Kayne

Universal Serial Bus (USB) 2.0 is an external interface used on computers and other digital devices to transfer data through a cable. The designation “2.0” refers to the standard or version of the interface and it was released in 2000. While USB 3.0 was made standard in 2008, it is backward compatible with older versions. The primary difference between each version has been a major increase in transfer rates, with USB 2.0 improving upon the original release and 3.0 being even faster.

A variety of USB cables.
A variety of USB cables.

Major Features

USB is a plug-and-play interface, which means that a computer does not need to be powered off in order to plug in or unplug a component. For example, a media player can be connected to a computer via a USB while the machine is still in use, making these devices "hot swappable." The computer registers the device as another storage area and shows any files it contains. Other types of ports often require that someone shut down a computer before making such a connection, which led to much of the format's popularity.

A USB wireless network adapter.
A USB wireless network adapter.

The maximum approved length for a USB 2.0 cable is about 16 feet (5 meters). This limitation is based on how quickly a signal travels through the cable. If it takes too long, then the connected devices indicate that it was lost, and anything over about 16 feet (5 meters) exceeds this time.

USB hubs can be used to connect USB 2.0 devices to older computers.
USB hubs can be used to connect USB 2.0 devices to older computers.

Upgrade From 1.0

When USB standards change from an existing version to a newer version, as they did from 1.1 to USB 2.0, the major improvement is often the speed at which data transfers between connected devices. In 1.0 and 1.1, there were two speeds available: "low speed" with a rate of 1.5 megabits per second (Mbit/s) and "full speed" at 12 Mbit/s. USB 2.0 improved upon these with "hi-speed" transfer rates of 480 Mbit/s. Since this standard is typically backward compatible, the 2.0 version includes the older "full speed" and "low speed" rates to function with 1.0 devices.

Many computer mice are USB compatible.
Many computer mice are USB compatible.

Even in USB 2.0, "low speed" was often used for data transfers between a computer and a mouse or keyboard, except for high-end gaming devices. Memory sticks and external hard drives became much more powerful with the 2.0 standards, since they often ran into "bottlenecks" with older transfer rates. A bottleneck is a point at which data is slowed down by limitations in transfer rate, such as the slower speeds of 1.0 ports, even though the devices themselves can send and receive data much faster.

USB cables are used to connect devices -- such as printers, keyboards and music players -- to computers.
USB cables are used to connect devices -- such as printers, keyboards and music players -- to computers.

Common Devices

Aside from media players, many other external devices use these data ports, including digital cameras, mobile phones, and newer cable boxes. Native components also make use of this interface, such as mice, keyboards, and external hard drives, as well as printers and networking hardware. One of the most popular and convenient USB 2.0 gadgets is a memory stick, which can store data for easy transfer between machines.

Introduction of 3.0

In 2008, USB 3.0 was officially adopted as the new standard for this format. It introduced new connections that included more pins, allowing for "SuperSpeed" data transfer rates of up to 5 gigabits per second (Gbit/s). The 3.0 standard maintained backward compatibility, including "hi-speed" and "full speed" rates to function with older USB 2.0 devices.

What Is the Difference Between USB 2.0 and 3.0?

Acting as an upgraded version of USB 1.0 and 1.1 and released in the year 2000, USB 2.0 is a type of interface that allows for faster speeds than its first versions. It is sometimes referred to as Hi-Speed USB. This 2.0 interface was backward compatible with previous versions of USB, meaning a USB 2.0 port still functions with a USB 1.1 cable, albeit with version 1.1 speeds. The reverse is also true: A USB 2.0 cable will function with a USB 1.0 port, and a USB 3.0 interface will work with a USB 2.0 port, just with speeds limited to whatever the oldest version of USB on either side is plugged into.

Likewise, USB 3.0 allows for much faster speeds than USB 2.0 and is also backward-compatible. This 3.0 version allows for 5 Gbit/s speeds.

Is There a Difference In Power Efficiency Between USB 2.0 and 3.0?

USB 3.0 devices use more power when transferring data but less power when plugged in and idle. This means USB 3.0 interfaces can charge devices faster than USB 2.0. USB 3.0 is more power-efficient than 2.0 because it has more sophisticated control over when it uses power.

How Fast Is USB 2.0?

Whereas USB 1.0 maxed out at 1.5 Mbit/s, USB 1.1 allowed for 12 Mbit/s data transfer speeds, and USB 2.0 offers 480 Mbit/s speeds. Note that a USB 2.0 interface will require a 2.0 port to maintain those data speeds. If the port is designed for USB 1.1 and a 2.0 interface is plugged in, it will top out at 12 Mbit/s.

Do devices still use USB 2.0?

Because USB 3.0 is superior to USB 2.0, it tends to be more expensive. This means USB 2.0, while not being as fast as USB 3.0, is still prominent today and found on many devices and computer motherboards.

USB 2.0 is perfectly adequate for peripherals that do not require fast data transfer speeds, such as mice and keyboards. Because these devices are not designed for data transfer like flash drives or external hard disks are, they would not benefit much from a 3.0 interface.

Many flash drives still use USB 2.0 to save on cost. If you’re using your flash drive to move small amounts of data around, such as documents or spreadsheets, you will notice little difference between disks that use USB 2.0 and 3.0. On the other hand, if you’re moving HD video or 4K images from one device to another, a USB 2.0 interface will take a much longer amount of time to complete the task than a USB 3.0 interface would.

What Is a USB 2.0 Port?

Typically found on computers, cameras, and other digital devices, a USB 2.0 port was standard until 2008 when USB 3.0 became the new data speed standard.

How do I identify a USB 2.0 port from a USB 3.0 port?

A USB 3.0 port (as well as any USB 3.0 interface, such as on a cable or flash drive) can be visually distinguished by its blue connector. USB 2.0 ports are often black or white. If you look at a port or connector and it looks like half of it is blue, it is likely a USB 3.0 interface. If you plug that device into a USB 3.0 port, you will get those 5 Gbit/s speeds.

Is USB-C different from USB 3.0?

Yes. USB-C is an interface designed by the same group of companies that manage the different types of USB and has become popular for its power transfer speeds, particularly in devices such as smartphones. Because it is an entirely different shape than USB 1.0, 2.0, and 3.0 ports, it is not compatible with these interfaces without an adapter. However, because they are electrically compatible, one can still use an adapter with a USB-C interface to connect to a USB 3.0 interface safely.

USB-C is an exceptionally versatile interface that can also work as an audio or video connector in addition to data and power. This is why they are convenient for many laptops. For example, with an adapter, a USB-C connector can act as a DVI interface, which is typically found on monitors to display the screen.

USB-C has become increasingly common as a superior alternative to Micro-USB for charging smartphones and other devices. USB-C data transfer speeds are typically around 10 Gbit/s, which is twice as fast as USB 3.0, though the latest generation is capable of 20 Gbit/s speeds.

USB 3.0 was introduced in 2008, providing much faster speeds than the 2.0.
USB 3.0 was introduced in 2008, providing much faster speeds than the 2.0.

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Discussion Comments


My computer has an old style usb port and I need a 2.0 port. Is there an adapter for this?


I have an external Seagate Hard Drive connected to a USB 2.0 port. If I buy a computer that has 3.0 USB ports will my external hard drive work connected to these ports.


Question: Does a usb CABLE have to be usb 2.0 compliant in order to make use of the benefits of usb 2.0 in peripheral usb 2.0 devices? Or, are usb cables all the same?


I have a 2003 Sony Vaio desk top and need to use USB 2.0 to run a new video capturing device (Easy Cap). It is not working. I assume according to your article here that my computer must have the older USB 1.1 (?). Is there a way to get around this without buying a new computer?

Thanks, Mistah


sgbaird -- How long can a USB cable be? The longest USB cable I've seen sold is 16 feet. I suppose they could make them even longer and it'd still work. There are wireless USB "extenders" too that can make the distance even further.


What is the maximum effective length of a USB cable connected between a computer and most external devices?

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