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: there are simple tricks you can use to charge your iPhone 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.
Pick the right charger
Tip number one: the tech specs of your charger or charging adaptor can make a big difference to charging speed. Not all iPhone chargers are born equal, and some charge much faster than others.
The iPhone chargers use a USB to Lightning cable*, which is attached to a USB charging point (adaptor). There are three different types of adaptor available:
- USB socket on a computer
- iPhone adaptor
- iPad adaptor
These three different chargers have different tech specs:
- Computer USB: 5 volts, 0.5 amps, 2.5 watts of power
- iPhone charger: 5 volts, 1 amp, 5 watts of power
- iPad Pro charger: 5.1 volts, 2.1 amps, 12 watts of power
This can seem confusing at first, but the figure that's relevant from a charging-speed point of view is wattage: this is a function of time, and defines the speed of energy transfer. The higher the wattage, the faster the charger can fill up your device's battery.
(We say 'can', because other factors may limit the charging speed, and in fact the "charger" is not the adapter, as that is to be found inside the phone, and it's that which regulates the charge coming from the adapter. Buying a 50-watt charger from a third-party accessory maker wouldn't necessarily result in proportionally faster charging times - or be a good idea for other reasons.)
So the charger you pick has a dramatic effect on the amount of time it takes to charge up an iPhone. Pretty obviously, you should always charge up an iPhone using the iPhone or iPad adaptor, rather than the USB socket on a computer: this is a far slower option.
(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 very 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.)
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.
*Don't worry if you're still using the older 30-pin connection rather than Lightning. Its charging speeds are the same.
You might also like: How to fix a broken iPhone or iPad or iPod charger
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.
See also: Best iPhone 7 & 7 Plus cases
Charge when connected to a Mac
Let's say that for various reasons already mentioned you do wish to charge your iPhone via a Mac's USB port. 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.
Read next: How to improve iPhone & iPad battery life
Can you use an iPad charger to charge up an iPhone, or an iPhone charger to charge up an iPad?
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.
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.
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.