Charging an iPhone or an iPad seems like a straightforward process, but it can be slow. However, many Apple fans don't realise that the speed of charging varies depending on the way you charge the device, and that there are simple tips and tricks you can use to fill the battery faster. Armed with a bit of knowledge you can dramatically reduce the time it takes to charge up an iPhone's battery.

In this feature we look at how to charge up your iPhone (or iPad) quickly and safely, and some of the best ways to make iPhone charging a faster and more efficient process. Elsewhere we discuss the related but separate issue of getting an iPhone battery to last longer off a single charge.

If you're having trouble getting you kit to charge at all, you might prefer to read How to fix a broken iPhone charger.

Pick the right charger

Things used to be pretty straightforward here: if you wanted to charge your iPhone or iPad faster, you simply bought a faster charger.

Your iOS device will have been supplied with a full-size USB to Lightning cable, which you then plug into an iPhone or iPad charger, or perhaps a spare port on your Mac. But the charger you select has a dramatic effect on its charging time.

Generally speaking, the higher the number of watts, the faster your device will charge (a watt is a function of time, and defines the speed of energy transfer). But there is a limit - at some point your iPhone or iPad will hit its maximum ceiling for how much power it can take onboard at once. This is controlled by an adapter in the iPhone or iPad itself, not the charger.

The standard charging options

A USB port on your computer is typically just 2.5W (5V, 0.5A), while a standard iPhone charger (£19 in the UK and $19 in the US) offers 5W (5V, 1A). Both these devices would be considered slow, especially when you consider that an iPad charger (£19 in the UK and $19 in the US) offers up to 12W (5V, 2.4A).

The latter is what we call 'fast' charging. It's not as fast as the likes of Qualcomm Quick Charge 4.0, but it's still much faster than what you'd get with a standard iPhone charger or a USB port on your Mac.

(Of course there may be other reasons why you would choose to charge via your Mac - having your iPhone connected to your Mac allows for easy file transfers, for instance, and only uses up one plug. But if speed of charging is your priority, you should plug your iPhone or iPad into the mains.)

How to fast-charge an iPhone: 12W charger

USB-C

With the introduction of the iPhone 8, iPhone 8 Plus and iPhone X, Apple confused things further. It talks about these devices being able to fast-charge to 50 percent in 30 minutes - but it's a feat it achieves not with a standard Lightning cable and iPhone charger but with a USB-C to Lightning cable and a USB-C charger.

USB-C is capable of USB 3.1 speeds, whereas a typical USB charger will be limited to USB 2.0. But you don't get a USB-C to Lightning adaptor cable in the box with your new iPhone, and neither do you get a plug charger capable of delivering a faster charge through that adaptor.

Apple sells these products separately, of course. It'll cost you £25 in the UK or $25 in the US for the adaptor cable, while the USB-C charger costs £49 or $49 for the cheapest 29W model. There are also 61W (£69/$69) and 87W (£79/$79) options that won't fill your iPhone any faster than the 29W model but may come in handy if you also have a USB-C MacBook.

That is the fastest way to charge your iPhone or iPad, but it's not a cheap option.

Bear in mind that the adaptors above are the official Apple units; third-party charging products are likely to vary in their specs. If using a non-Apple adaptor you should check the wattage and see what it delivers compared to an Apple charger. It's possible that the two will offer significantly different charging speeds.

Wireless charging

If iPhone chargers weren't complicated enough already, Apple also introduced wireless charging on the 2017 models. A standard wireless charge is 7.5W, faster than charging your iPhone or iPad via your Mac or a typical iPhone charger, but slower than using a 12W iPad charger.

(Initially the wireless-capable iPhones were capped at just 5W, but this was unlocked to 7.5W via the iOS 11.2 software update - so check your phone is reasonably up to date if you're not getting expected charging speeds.)

Remove the case

A lot of people swear by this simple tip for more efficient charging: take the case off your iPhone. But we're not convinced that it will produce appreciable benefits, at least on the speed front.

The problem you're avoiding here is heat buildup: you'll have noticed that iOS devices can heat up when charging (particularly when charging and running an app at the same time - so don't do that), and a case can make this problem worse.

Excess heat can cause issues with the battery capacity, but the main effect of heat is to cause the battery to wear out faster.

So taking off the case may not produce appreciable improvements in charging speed - but it could mean the battery last longer. So if you've ever noticed your iPhone or iPad heating up during a charge (we've noticed this more with iPads than with iPhones, but both can be affected), play it safe and take the case off when charging in future.

Charge when connected to a Mac

How to fast-charge an iPhone: Using System Report to monitor charge levels

Let's say that for various reasons already mentioned you wish to charge your iPhone via a Mac's USB port instead of a mains plug. Are there any ways to make that faster?

There have been several rumours that Mac computers contain a high-power USB port. This isn't strictly true, but different Apple computers do have different specifications for their ports. This may affect charging speed: variations in current (measured in amps or milliamps) in turn change the all-important wattage. Power, as our patient technical editor has explained to us, is produced by multiplying voltage by current.

They can also affect whether the ports are able to power your devices at all. This explains why you may have plugged your iPad into a Mac and seen the error message 'Not charging', or simply found that the device didn't charge.

A Mac with USB 2.0 ports (typically a MacBook Air) is rated at 500mA at 5V, while a Mac with USB 3.0 ports offers 900mA at 5V. But beyond this, a Mac with USB 3.0 can provide up to 1100mA at 5V under certain conditions (as described in this Apple support document).

Apple makes it very clear how you should go about charging an iPhone or iPad via a Mac:

  • An Apple peripheral device must be plugged directly into an Apple computer or display.
  • Your Apple computer or display must be powered on and must be awake.
  • The port providing extra power is determined by the first Apple peripheral or device to connect to the Apple computer.

It's worth noting that this doesn't apply to Macs running Boot Camp.

But if you do want to charge an iPhone via a Mac computer you should plug in only the iPhone (or make sure it's plugged in first) and keep the computer awake while charging proceeds. In the case of laptops, make sure the Mac is itself plugged into the mains.

Can you use an iPad charger to charge an iPhone, or an iPhone charger to charge an iPad?

How to fast-charge an iPhone

Yes, you can charge any iPhone safely using an iPad charger. There has been much debate on the Apple Discussion forums about this - even suggesting that using an iPad adapter to charge an iPhone will fry or severely damage the iPhone's battery.

The general consensus - over the 23 pages of raging debate - is that because the actual "charger" is inside the phone, not the adapter, it won't damage the iPhone to use a higher-wattage adapter. The load determines the current drawn from the power source. The power source does not push current; it supplies voltage up to a specified maximum available current.

If you're super cautious then stick with the charging adapter that came with your iPhone, but here's Apple's confirmation that the 12W iPad adapter is compatible with most iPhones.

How to fast-charge an iPhone: Apple iPad charger adapter charging iPhone

On the other side, yes you can charge an iPad using a lower-wattage iPhone adapter, but this will be slower than using the 12W adapter that it ships with.

Use Airplane Mode

One neat trick that's worth mentioning is that you can charge an iPhone slightly faster by switching on Airplane Mode - but we do mean slightly.

This is because it turns off 3G and Wi-Fi and uses less power while charging. Open Control Centre and tap the plane-shaped icon when charging. Note that while Airplane mode is activated you won't be able to take phone calls or use your iPhone to browse the internet; but the iPhone will charge a little bit faster.

How to fast-charge an iPhone: Airplane Mode

Turn the iPhone off

In a similar way, switching your iPhone off during charging enables it to charge faster. Again, the difference will be fractional, but may be worth it.

This is because the iPhone isn't draining any power at all during charging. Plug the iPhone into the wall charger, hold down the Sleep/Wake button and use the Slide To Power Off icon to switch off the iPhone. Leave it for a couple of hours to fully charge.