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iPhone 12 MagSafe charger only hits 15W when paired with a 20W adapter

Magsafe Charger Hero
Magsafe Charger Hero (Image credit: Joe Wituschek / iMore)

What you need to know

  • There's a new MagSafe charger for iPhone 12 this year.
  • The charger offers users up to 15W of power.
  • This can only be achieved when paired with a 20W charging adapter.

Apple's MagSafe charger for iPhone 12 only offers 15 watts of power when paired with a 20W power adapter, according to the latest tests.

Zollotech (Aaron Zollo) has put the new magnetic charger through its paces over on YouTube using a power meter to determine the actual power output of the device.

Zollo has confirmed that Apple's MagSafe charger can only charge at its maximum output of 15W when paired with Apple's 20W charger. Testing revealed that using the charger with an 18W adapter like the one shipped with the iPhone 11 Pro offered a slightly lower power output of around 13W. Performance was noticeably worse using third-party accessories.

The testing reflects Apple's own website, which has previously confirmed that you'll need a 20 watt iPhone 12 charger to get the most out of the new accessory:

Connect the USB-C connector on your MagSafe Charger to a 20 watt (W) or greater Apple USB-C power adapter. Your MagSafe Charger needs a power adapter of at least 12 W of power, and your iPhone charges less quickly when using a power adapter that provides less than 20 W. You can also connect to a USB-C port on a Mac or to third-party adapters that comply with applicable safety standards.

It has already previously emerged that Apple's 18W charger from last year does not officially support fast charge on the iPhone 12. According to Apple's website, you also need this 20W power adapter to fast charge the device, unofficially, our early testing indicates charging with the 18W adapter offers similar charging times.

Whilst the MagSafe wattage may be restricted by the power adapter you're using, our intial testing shows there might not be that much difference. Some numbers:

  • 18W charges more than 50% in 30 minutes
  • 20W charges more than 50% in 30 minutes
  • 18W with MagSafe about 30% in 30 minutes
  • 20W with MagSafe about 30% in 30 minutes

Apple introduced MagSafe as a new way to charge the iPhone 12, along with a range of MagSafe accessories including the charger and a new Apple Wallet, you can see our roundup of the best iPhone 12 chargers here.

Stephen Warwick
News Editor

Stephen Warwick has written about Apple for five years at iMore and previously elsewhere. He covers all of iMore's latest breaking news regarding all of Apple's products and services, both hardware and software. Stephen has interviewed industry experts in a range of fields including finance, litigation, security, and more. He also specializes in curating and reviewing audio hardware and has experience beyond journalism in sound engineering, production, and design.

Before becoming a writer Stephen studied Ancient History at University and also worked at Apple for more than two years. Stephen is also a host on the iMore show, a weekly podcast recorded live that discusses the latest in breaking Apple news, as well as featuring fun trivia about all things Apple.

2 Comments
  • This is very interesting. Is Apple somehow crippling all 3rd party charging blocks and their own laptop charging blocks when they are used with the new MagSafe puck?
  • The issue stems from Apple’s non-standard PD setup. The 20W adapter uses 9V x 2.22A, for a total of 19.98W. The only other charger I’ve seen that has that is the new Anker Nano 20W. My guess if a charger does not use that PD (different voltage and amperage combo, in other words), it defaults to a max of 10-ish watts (5V x 2A).