USB-C was designed as a robust multi-functional standard that would finally allow a single, industry-supported connector to deliver high power and ultra-fast data transfers. In the hustle and bustle of moving from USB Type-A and Apple’s original MagSafe and MagSafe 2 laptop magnetic charging systems, the joy of a single cable can be lost.

The great thing about USB-C is that you can plug any USB-C plug into any USB-C port. The sockets on the two devices agree on what they have in common. Sometimes it’s terrible, like 480Mbps with active Thunderbolt 3 cables and USB-C charging cables instead of 10-40Gbps! Other times it’s great, like not having to worry about the power of cables, chargers, or laptops when plugging them all in together.

All Thunderbolt 3 and 4 cables connected between two Thunderbolt 3 or 4 ports can carry up to 100W. With USB 3.x or USB4 on both ends, the maximum can be 60W, but it depends, like everywhere else.

Regular USB-C charging

Apple has released laptops with USB-C starting in 2015 that can draw between 29W and 100W over standard USB-C.

It is important to note:

  • If you use a 60W USB-C cable for USB only, the cable will not attempt to transmit more than 60W.
  • If you are using a USB-C charger that could provides more power than your Apple laptop can handle, the charger will not send that level of power to your computer. Your computer is also designed to prevent charging at too high a power.

The only variable in this equation is the cable itself. In the early days of USB-C, some cables were produced cheaply by obscure companies, while USB-C cables were quite expensive and in short supply. Now I would argue to stick with a well-known name such as Belkin or Other World Computing, which have a known manufacturing reputation and can be contacted in case of a problem.

Charging MagSafe 3

Apple has confused things a little by introducing its 14-inch and 16-inch MacBook Pro models with MagSafe 3 in 2021, replacing earlier laptop variants. MagSafe 3 cables feature Apple’s latest proprietary connector on one end and USB-C on the other. These MacBook Pro models, as well as the 2022 MacBook Pro, either come with a high power adapter, or you can upgrade to an adapter with lower models: it’s 67W for the MacBook Air, 96W for the 14-inch MacBook Pro. and 140W for the 16-inch MacBook Pro.

If you use a 96W adapter, whether it’s a MagSafe 3 cable or just a USB-C cable with a 14-inch MacBook Pro or 2022 MacBook Air, it turns on a fast charging mode that Apple says can charge your Mac up to 50 percent in no more than 30 minutes. (To avoid overcharging the lithium-ion battery, this fast charge is limited to 50 percent charge.)

The 16-inch MacBook Pro requires a 140W Apple charger and MagSafe 3 cable to fast charge. In any other scenario, the maximum charging power is 100W.

This Mac 911 article is in response to a question posed by Macworld reader Nicholas.

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