Newer iPhones support wireless charging – and when iOS 11.2 releases soon it will unlock even faster wireless charging with certain charging docks. But how fast exactly is that, and how does it compare to regular charging speeds? Also – while we’re on the subject, what’s the best way to “fast charge” an iPhone or iPad?

This stuff can get confusing so let’s try to break down the facts about charging speeds.

Wireless charging

This is a feature only available on iPhones 8, 8 Plus, and X. Just place the device on a compatible charging pad and it’ll start gaining juice. Currently, there’s a 5W maximum for wireless charging but this will be extended to 7.5W with iOS 11.2 to improve speeds. Even then, though, this type of charging can never be as efficient as a wired connection.

Wired charging

All iPhones and all iPads can charge using any official Apple adapter without harming the device, so it’s safe to mix and match despite the chargers varying in power. Take a look at the small print on the adapter to see the wattage you’re dealing with. iPhones ship with 5W chargers while iPads come with 10W or 12W depending on the exact model.

Using a 5W charger on an iPad will result in extremely slow charge times, so it’s best avoiding that situation. Conversely, using a beefier charger with an iPhone should speed things up right? Not necessarily. Most models of iPhone cap the power intake at 5W, so although it’s safe to use a higher rated charger you won’t see any benefits.

Fast charging

That said, more recent iPhones and iPads are capable of extremely fast charging if you have the right kit. The following six devices are compatible with “fast charging,” which can take an iPhone from 0% to 50% in just half an hour: iPhone 8, iPhone 8 Plus, iPhone X, iPad Pro 12.9-inch (1st gen), iPad Pro 12.9-inch (2nd gen), and iPad Pro 10.5-inch.

To fast charge you’ll need a USB-C to Lightning charger running at either 29W, 61W, or 79W. These are much chunkier than the regular adapters, and if you have a MacBook you likely have one of them already. You’ll just need to pick up a new cable with USB-C on one end and Lightning on the other.

Which is fastest?

The guys at Birchtree have done some experiments to see exactly how these methods compare to each other in terms of speed. The chart below shows fast charging in red, regular wired charging in yellow and the two levels of wireless charging in green and blue. Big differences, huh?

These findings show that investing in a fast charging setup will fill your battery to 50% twice as quickly as a regular wire, although the benefits are smaller over a two-hour cycle. Meanwhile, the improved wireless charging coming with iOS 11.2 doesn’t look like that much a step up, and is still about half the speed of the regular 5W charger that comes with all iPhones.

Wireless charging is still a great feature, but remember that it’s useful for its convenience rather than it’s speed. If you need a quick top-up, it’s always better to use a cable.