USB-C to USB-C cable

What Is USB-C?


  • USB-C is an open source connector maintained by the USB-IF.


  • USB standards are the interface technology that governs data transfer rates.

  • Thunderbolt 3 uses USB-C connectors. But its own technology has limited compatibility with USB standards.

  • With so many power and interface options of course you have a lot of cable options, too.

USB-C Is a Type of Connector

USB Type-C connectorUSB-C, also known as USB Type-C, is the latest USB connector system. It is distinguishable by its symmetrical, oval shape. USB-C itself is only a type of connector. It does not necessarily support USB 3.1 or USB Power Delivery. The connector is common to several technologies. Those technologies are what dictate which functions are supported.

The USB Type-C 1.0 specification was finalized in September 2014. It started appearing on a significant number of consumer electronics in 2015/2016. Since then it has appeared on an increasing number of devices.

Do I Need USB-C?

Whether you need the new connector is irrelevant. At some point in the future (if not already) you will buy a new device which uses USB-C. You don’t get to choose between a USB-C and non-USB-C version. USB-C is the future of USB development, so we expect more and more devices will move to it over time.

Once you have a USB-C device then you may (or may not) have need for new USB-C accessories. Laptops with USB-C tend to need dongles to work with any other connection. Phones with USB-C will need at least a USB-C to USB-A cable to charge. Buying new USB-C accessories will provide better performance and easier connections. But there are plenty of adapters available if you aren’t ready to go all in on USB-C.

USB Connection Types
Legacy USB connectors

Legacy USB connectors

USB-C is the newest type of USB connector. Many legacy connectors are still in use today and often more recognizable.

  • USB-A: What most of us think of when we think “USB.”
  • USB-B: Found on USB printers, USB 2.0 external hard drives, and similar devices that receive data. There is a USB 1.1/2.0 version and a larger USB 3.0 version.
  • USB mini-B: The original miniaturized USB port. They were deprecated in 2007 and replaced by micro-B.
  • USB micro-B: Smaller than the mini ports, they are still produced today. Often used instead of USB-C for devices that don’t need as much power or data transfer speed.

USB-C can replace all the above connectors, in theory. But production cost will keep some of the older USB connectors around for a while longer. With computers a USB-C 3.1 connection costs 4-10 times as much as a USB-A 2.0 connection. And a USB-C 3.1 Gen 2 connection costs 7 times as much as a USB-A 3.0 connection. The faster data rate isn’t worth the added cost for all customers.

USB-C has the advantage of being reversible. You can plug in a USB-C cable in either orientation. Where as all the legacy connections only work in one orientation. No more plugging it in, doesn’t fit, flip it, and plug it in again.

It also supports newer, fast USB standards. These include USB Power Delivery, for more power. And USB 3.1 and 3.2, for faster data transfers. The legacy connectors are limited with their power and data transfer rates. And will not support future standards.


USB-C Power

All USB-C connections support (or should support) up to 15W power output/input. Along with USB-C a new fast charging standard was also created: USB Power Delivery. Many USB-C chargers and devices today support USB Power Delivery. Which allows for up to 100W power transfer.

Power Profiles

All USB-C chargers and power banks offer one or more power profiles. These tell us what range of power they can provide for. And are the best way to determine if a charger is a good fit for a device. For this explainer we’ll ignore Power Delivery 1.0. It allowed for some weird power profiles we no longer see in the market.

Power Delivery 2.0/3.0 use five voltages: 5V, 9V, 12V, 15V, and 20V. Each can carry up to 3A of current. But they can offer less current under certain configurations. 20V can go up to 5A of current. Watts = voltage x current, so 20V/5A = 100W. If a charger offers a certain power profile then it must support certain other power profiles. For example, if it offers 15V/3A then it must support 3A on both 5V and 9V. And if it offers 20V then 5V, 9V, and 15V must also be offered. 12V is a completely optional power profile.

Here’s an example of two different, but within spec 45W USB-C PD chargers:

  • 5V/3A (15W), 9V/3A (27W), 12V/3A (36W), 15V/3A (45W)
  • 5V/3A (15W), 9V/3A (27W), 15V/3A (45W), 20V/2.25A (45W)

Both are acceptable power profiles for a 45W USB-C Power Delivery charger. As both offer 15V/3A they must also offer 9V/3A. 20V/2.25A is optional. But if 20V/2.25A is present then 15V/3A must also be present. Finally, 12V/3A is optional.

To go above 60W a charger offers more than 3A, but only at 20V. So a 100W USB-C charger will only support 5-15V power profiles equal to a 45W charger. All higher wattage is at 20V only.

When choosing a charger for your device the voltage must match. But the charger can offer more current than the device needs. The device controls the current. Power is drawn from the charger, rather than pushed to the device.

Fast Charging Standards

The 15W supported by all USB-C is considered normal charging. Fast charging standards increase voltage and/or current beyond 5V/3A to charge a battery faster. Fast charging over USB pre-dates USB-C by a decade, but newer standards have been created for the new connector.

USB Power Delivery (USB PD)

An open standard, created alongside USB-C and maintained by the USB Implementors Forum. All USB PD is USB-C, but not all USB-C is USB PD. It allows for 15-100W, powering everything from a phone to a large gaming laptop.

Qualcomm Quick Charge 4+

Qualcomm’s Quick Charge 4+ operates exclusively over USB-C. It is USB-C compliant (unlike QC 3.0) and works alongside USB Power Delivery. A QC 4+ charger can act as a USB PD charger. Any a QC 4+ device can fast charge from USB PD.

Quick Charge 3.0, Samsung Fast Adaptive Charging, Huawei SuperCharge, and more

Many other fast charging standards, both new and old, are available on a variety of USB-C devices. They are not compliant with USB-C specs. And are proprietary technology. But they work without issue in the real world, provided the charger and device share the same technology.

Learn more about USB Fast Charging Standards.


USB Standards

USB (Universal Serial Bus) standards are interface technology. It is separate from the USB connection. Some USB-C connectors support some of these standards. The different standards impact how fast your data transfers between devices can be. All USB standards are backwards compatible. For example, a USB 3.1 cable will support a USB 2.0 connection.

USB Legacy Standards

USB standards have been around since 1998. But thanks to its backwards compatibility these are still supported by USB-C.

  • USB 1.1: Data rates of 1.5-12 Mbps. Commonly found on input devices, such as keyboards and mice.
  • USB 2.0: Data rate up to 480Mbps. Slow by today’s standards. The likely standard found if your device doesn’t specify. Supported by most USB-C ports and cables.
  • USB 3.0: Data rate up to 5Gbps. Supported by some USB-C ports, but under a new name: USB 3.1.
 USB 3.1

USB 3.0 was renamed to USB 3.1 when USB-C was released. Afterwards a second version of USB 3.1 was added. Technically USB 3.0 refers to USB-A connections and USB 3.1 refers to USB-C connections.

  • USB 3.1 Gen 1: Data rate up to 5Gbps. The same as USB 3.0, but renamed.
  • USB 3.1 Gen 2: Data rate up to 10Gbps.
USB 3.2

USB 3.2 is the current version of USB standards. It absorbed the two USB 3.1 standards above and renamed them (again). It also added two new standards which use multi-lane technology.

  • USB 3.2 Gen 1×1: Data rate up to 5Gbps. Same as USB 3.0 and USB 3.1 Gen 1.
  • USB 3.2 Gen 1×2: Data rate up to 10Gbps. Uses new dual-lane tech.
  • USB 3.2 Gen 2×1: Data rate up to 10Gbps. Same as USB 3.1 Gen 2.
  • USB 3.2 Gen 2×2: Data rate up to 20Gbps. Uses new dual-lane tech.
USB 4

USB 4 has been announced. It is expected to be published in 2019 and introduced in new products some time after that. It brings the benefits of Thunderbolt 3 to USB standards, supporting data rates up to 40Gbps. No word on what the new naming scheme will be.

USB Standards & Their Marketing Names

As you can see, USB standards get confusing past USB 3.0. To counter this the USB-IF has suggested marketing names for each standard. Unfortunately these aren’t often used by online retailers. And with USB 3.2 it doesn’t always distinguish between the old and new standards.

USB SuperSpeed logos

USB SuperSpeed logos

  • USB 1.1 = Low Speed
  • USB 2.0 = High Speed
  • USB 3.0 = SuperSpeed
  • USB 3.1 Gen 1 = SuperSpeed
  • USB 3.1 Gen 2 = SuperSpeed 10Gbps
  • USB 3.2 Gen 1×1 = SuperSpeed
  • USB 3.2 Gen 1×2 = SuperSpeed 10Gbps
  • USB 3.2 Gen 2×1 = SuperSpeed 10Gbps
  • USB 3.2 Gen 2×2 = SuperSpeed 20Gbps

Note how the marketing names don’t allow you to tell the newer USB 3.2 Gen 1×2 from the older USB 3.2 2×1. They also won’t tell you if the device is using USB-C or a legacy connector. On the retail end a product can list only “USB 3.2” and be legal. But that doesn’t tell you if it supports 5Gbps, 10Gbps, or 20Gbps. You’ll need to read full tech specs to verify you are getting the connection speed desired.


Thunderbolt 3

Thunderbolt is a hardware interface standard created by Intel and Apple. Thunderbolt 3 released in 2015 and implemented the use of USB-C connectors. Previous versions had used Mini DisplayPort connectors.

Thunderbolt 3 uses its own cables, as they need to support technology not found in other USB-C cables. A Thunderbolt 3 cable may look a lot like a USB-C cable. But their specs are quite different. Thunderbolt 3 cables have some compatibility with USB-C ports.

Thunderbolt logo

Thunderbolt logo

There are two types of Thunderbolt 3 cables:

Passive Cables

  • Support 40Gbps data transfer rates up to 0.5 meter in length
  • Support 20Gbps data transfer rates at longer lengths
  • Also supports USB 3.1 Gen 1 (5Gbps)

Active Cables

  • Support 40Gbps data transfer rates at any length
  • Also support USB 2.0 (480Mbps)

Either type of cable will support up to 3A/60W of power. Many can support up to 5A/100W.


USB-C Cables

As USB-C power and standards get complicated, so do USB-C cables. There are different cables for supporting the different USB standards and power levels. And of course different types of cables for connecting USB-C to USB-C, USB-A, and Lightning. No one type of cable handles everything.

USB-C to USB-C Cables

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USB-C to USB-C cables are often divided by the USB standard they support. But they are also divided by how much current they can handle. With most cables you cannot visually identify their specs. You have to pay attention to their technical specs and mark different cables if you have a mixed collection.

USB Standards

The primary way USB-C cables are listed is by the USB standard they support.

  • USB-C to USB-C 2.0: These are the cheapest cables. They support up to 480Mbps data transfer rates. They will work with USB-C 3.1 ports. But they are limited to their own data transfer rate.
  • USB-C to USB-C 3.1: These are USB 3.1 Gen 1 supporting cables. They allow up to 5Gbps data transfer rates. Backwards compatible with USB-C 2.0.
  • USB-C to USB-C 3.1 Gen 2: The most expensive cable. They support up to 10Gbps data transfer rates. Backwards compatible with USB-C 2.0.

When USB 3.2 is readily available we’ll see how that changes the USB-C cable line up.

USB Power

Both USB-C 2.0 and USB-C 3.1 cables will charge devices at the same rate, up to 60W. All USB-C cables should support 3A. And there is no charging performance gain by buying a more expensive USB-C 3.1 cable. That said, some USB-C cables can support up to 5A of current. This allows them to work with 65-100W chargers. Either a USB-C 2.0 or 3.1 cable can support 5A.

If the current isn’t listed then the cable supports 3A. A 5A cable may be listed as 5A or 100W. You only need a 5A cable if you have a charger and device that operate above 60W. Otherwise a 3A cable will suffice. A 3A cable can work with a 65-100W charger, but will limits the charge to 60W or less. A 5A cable does not charge smaller devices any faster than the 3A cables.

eMarkers

USB-C to USB-C cables which offers USB 3.1 or 5A support are required to include an eMarker. The eMarker works with USB-C communications. It allows a device to verify the cable supports higher data transfer rates and/or current. Think of it as an ID tag, which tells the device exactly what the cable is capable of.

USB-C to USB-C cables which only offer USB 2.0 and 3A support are not required to include an eMarket. And most do not to save cost.

Unless the cable has its specs printed on it you cannot visually tell a USB 2.0 cable from a USB 3.1 cable. Or whether it can handle 3A or 5A. If you bought the cable online you can check your order history and look at the specs. Otherwise you need a USB-C testing device to read the eMarker.

USB-C to USB-A Cables
USB-C to USB-A cable

USB-C to USB-A cable

Like USB-C to USB-C cables, USB-C to USB-A cables are often divided by the USB standard they support. Unlike C-to-C cables they all have a 3A current limit.

  • USB-C to USB-A 2.0: These are the cheapest cables. They support up to 480Mbps data transfer rates. They will work with USB 3.0 ports. But they are limited to their own data transfer rate.
  • USB-C to USB-A 3.0: These can also be labeled as USB-A 3.1. They allow up to 5Gbps data transfer rates. Backwards compatible with USB 2.0.
  • USB-C to USB-A 3.1 Gen 2: The most expensive cable. They support up to 10Gbps data transfer rates. Backwards compatible with USB 2.0.

You can charge some USB-C devices with a USB-C to USB-A port. But the power draw is limited by USB-A specifications. Small USB-C devices tend to draw up to 10W. A Quick Charge enabled device and a Quick Charge USB-A port can get up to 18W. They do so by working outside USB-C specifications.

USB-C to Lightning Cables
USB-C to Lightning cable

USB-C to Lightning cable

Newer iPhones and iPad Pros support USB Power Delivery. But most of those models use a Lightning port, not USB-C. So Apple made a USB-C to Lightning cable. This allows certain models to connect to a USB-C PD charger and fast charge.

  • iPhone 8
  • iPhone 8 Plus
  • iPhone X
  • iPhone XR
  • iPhone XS
  • iPhone XS Max
  • iPad Pro, 1st Gen
  • iPad Pro, 2nd Gen

Older iPhones can use the cable. But they don’t gain a faster charge from it. The latest iPad Pro (3rd Gen, 2018) has a USB-C port and can use USB-C to USB-C cables.

USB-C is an open connector, but Lightning is owned and controlled by Apple. Apple uses their MFi certification program to verify certain Lightning products work. Newer versions of iOS may warn or even refuse to work with a non-certified product. Until 2019 Apple made the only MFi certified USB-C to Lightning cables. Third party, MFi certified USB-C to Lightning cables are now appearing on the market.


USB-C Adapters

USB-C’s high bandwidth allows it to take the place of several older connectors. On a laptop USB-C ports can (and do) take the place of USB-A, Ethernet, HDMI, and power ports. This is convenient if all your accessories also use USB-C. Otherwise it requires adapters to work with older connections.

  • USB-C to HDMI
  • USB-C to DisplayPort
  • USB-C to VGA
  • USB-C to Ethernet
  • USB-C to USB (USB-A)
USB-C Hubs

A single USB-C post can handle several connections. As such USB-C hubs and docks are also available. These allow several older connections to go through a single USB-C port.

Unfortunately they don’t always work well. Models without their own power adapter can only handle so much. Some models are tested against only some model laptops. And not all laptops implement USB-C as well as they should. Some have even been found to cause network interference.

If considering a USB-C hub get one that only has the connections you need. And go over reviews, looking for other users who have the same model laptop as you.


USB Implementors Forum

USB-IF logo

USB-IF logo

The USB Implementers Forum (USB-IF) is a non-profit organization formed by Agere Systems, Apple, HP, Intel, Microsoft, and NEC. It promotes and markets USB. It also maintains USB specifications and a standards compliance program.

They offer USB-IF certification for USB-C products that meet their strict standards. To gain certification a product must pass their USB-IF Compliance Program. And the producing company must be a dues paying member of the USB-IF.

USB-IF certification is a strong indicator of a good product. But lack of certification is not a strong indicator of anything. In some cases certification is forgone to support extra standards. For example, Quick Charge 3.0 is not allowed on a USB-C port under USB-IF standards. But some such devices exist, without any bad reports. Certifications started in late 2017. Products which pre-date that often don’t get submitted for certification. Some companies choose not to pay for USB-IF membership, such as RAVPower and Inateck. Others are members but ignore certification, such as Apple and HP.