How to Choose a Phone Charger: USB-C, Watts and GaN Explained

Buying a charger used to be simple: whatever came in the box. Now most phones ship with just a cable, and the shelves are full of bricks promising "super fast", "65W" and "GaN". Here is how to cut through the labels and pick a charger that is quick, safe and still useful in five years.

Start with the connector, then the standard

Almost every phone sold in the UK now charges over USB-C, and iPhones joined the club from the iPhone 15 onwards. That makes life easier, but the shape of the plug tells you nothing about how fast it will charge. What matters is the charging standard both ends agree to speak.

The one to look for is USB Power Delivery (USB PD). It is the open standard used by Apple, Google, Samsung and most laptop makers, so a single PD charger can top up your phone, tablet, earbuds and often your laptop too. Many Samsung phones also use a PD extension called PPS (Programmable Power Supply) for their fastest "Super Fast Charging" modes, so if you own a recent Galaxy, check the box says PD with PPS.

Some brands still use their own systems – older OnePlus, Oppo and Xiaomi models, for example – that only hit their headline speeds with the original brick and cable. They will still charge from a standard PD charger, just more slowly. If you value flexibility over the last few minutes of charging time, a good PD charger is the sensible choice.

How many watts do you actually need?

Wattage is the number everyone looks at, and it is the one most often oversold. A phone decides how much power it will draw; the charger only offers a maximum. Plugging a phone that tops out at 25W into a 100W charger will not make it charge four times faster – it will simply take its 25W and leave the rest unused.

• 20–30W covers the fast-charging limit of most iPhones and many mid-range Android phones.
• 45W suits flagship Samsung models that support their highest charging mode.
• 65W and above only makes sense if you want one charger for your laptop as well.

Bear in mind that phones charge fastest from empty to around half full, then deliberately slow down to protect the battery. A charger rated higher than your phone needs will not hurt it, but it will not change that curve either.

Multi-port chargers and the "shared power" catch

Two- and three-port chargers are brilliant for bedside tables and travel bags, but read the small print. The wattage on the front is usually the total, shared between ports. A "65W" dual charger might give 45W to one port and 20W to the other when both are in use, or split evenly. If you regularly charge a laptop and a phone together, look for a breakdown of the per-port output on the packaging or product page.

What GaN means (and whether it matters)

GaN, or gallium nitride, is a semiconductor material that runs cooler and more efficiently than traditional silicon in a power adapter. In practice it means smaller, lighter chargers for the same output. A 65W GaN charger can be about the size of an old 20W brick. It will not speed up charging by itself, but it makes powerful chargers easier to carry.

Don't forget the cable

A cable can quietly cap your charging speed. Basic USB-C cables are rated for 3 amps, which is plenty for 60W. Anything above that, such as a 100W laptop charger, needs a cable with an "e-marker" chip rated for 5 amps. For phones, any decent USB-C to USB-C cable from a reputable brand will do; problems usually come from cheap, thin cables that warm up or drop to slow charging after a few months of bending. If a known-good cable still connects loosely, lint packed into the phone's port is the usual cause – see how to clean your phone safely.

Keep an eye on length too. A two-metre cable is handy by the bed, but longer, thinner cables lose a little more power along the way.

Safety: what to avoid

Very cheap, unbranded chargers are one of the few phone accessories that can be genuinely dangerous. Poorly built units may lack proper insulation between the mains side and the USB side, or skip the temperature protection that stops them overheating. When buying in the UK:

• Check for a UKCA or CE mark and a proper manufacturer name and address on the packaging.
• Be wary of listings with prices far below the brand-name equivalent and vague specifications.
• Make sure the plug pins have insulated sleeves at the base – a quick way to spot a counterfeit.
• Stop using any charger that buzzes loudly, smells hot or feels too warm to hold.

Our quick checklist

1. USB-C output with USB Power Delivery (plus PPS for recent Samsung phones).
2. Enough watts for your phone's top speed – usually 20–45W.
3. Per-port output listed clearly if you buy a multi-port model.
4. A good-quality cable rated for the power you need.
5. Reputable brand, clear safety markings, sensible price.

Get those right and one small charger can look after everything in your bag – and keep doing so long after your current phone has been replaced.