Unlocking the Power: A Step-by-Step Guide to Reverse-Charging Your MacBook with Your iPhone in an Emergency

For those who own a modern iPhone and MacBook, there’s a handy trick you should know about. This trick specifically caters to iPhones with a USB-C port, which includes all models released since 2023 when the iPhone 15 replaced the older Lightning connector.

Since 2015, every modern MacBook has been equipped with USB-C ports, whether standard USB-C or versatile Thunderbolt/USB-4 ports. Chances are high that your current MacBook is less than eleven years old, making it compatible with this trick.

Picture this scenario: your MacBook is running low on battery, and you urgently need it to complete a task before a deadline. Unfortunately, you realize that you’ve left your charger behind. But don’t panic if you have your iPhone and a USB-C to USB-C cable because your iPhone can actually revive your drained MacBook.

It’s important to note that your iPhone won’t charge your MacBook in the traditional sense. This method will consume a significant portion of your phone’s battery. However, all it takes is a small amount of power to keep your MacBook operational, and your iPhone can provide that.

MacBooks typically come with a minimum of a 30W power adapter, with some models requiring up to 140W. In comparison, the iPhone has a maximum power output of 4.5W, so don’t expect a full charging solution. This method should be considered a last resort, as it’s not officially endorsed by Apple and its effectiveness may vary based on the iPhone and MacBook models used.

You may have better luck powering a MacBook Neo or MacBook Air compared to a 16-inch MacBook Pro, but there’s no harm in attempting it either way. This process won’t harm your iPhone or MacBook; at worst, nothing will happen at all.

The reason this trick can work lies in the USB Power Delivery (USB PD) protocol, where the power source isn’t predetermined in most USB-C charging connections. When you connect your iPhone to your MacBook, they negotiate who will be the power provider, with the MacBook typically winning and charging the iPhone.

Here’s a step-by-step guide to how we successfully used an iPhone 17 Pro to power an M3 MacBook Pro:

1. Turn off your MacBook (not just Sleep mode).
2. Connect the USB-C cable to the iPhone first.
3. Plug the other end of the cable into your MacBook.

In our case, the MacBook was powered off with the screen open. After connecting the USB-C cable to the MacBook (which was already at 90% charge), it immediately powered on. The battery icon on the screen indicated that the MacBook was charging, albeit slowly, and connected to a “slow charger.” Disconnecting the cable from either the iPhone or MacBook would reset the connection. To resume using the iPhone as the power source, the computer had to be shut down.

It’s crucial to remember that reverse-charging a MacBook with your iPhone should only be used as a last resort. Expect a significant drain on your iPhone’s battery for minimal, gradual gains. While iPhones can also charge AirPods and Apple Watch via USB-C (not wirelessly), using reverse charging with your iPhone should be reserved for emergencies rather than routine practice.