Turn over almost any phone charger and you will find a cluster of tiny printed symbols, numbers and letters. Most people never give them a second glance, but those markings tell you a surprising amount: how much power the charger can deliver, whether it has been designed for use in the UK, how it is insulated, and how to get rid of it safely when it finally wears out. This guide walks through the most common markings you will see on a mobile phone charger and explains what each one means in plain English.
The input rating: what the charger takes from the wall
Look for a line starting with “Input”. On most modern chargers it reads something like 100–240V ~ 50/60Hz. The wavy line (~) means alternating current (AC), which is what comes out of your wall socket. The voltage range tells you the charger will work on mains supplies from 100 to 240 volts, and the 50/60Hz figure covers the two mains frequencies used around the world.
UK mains electricity is nominally 230V at 50Hz, so any charger with a 100–240V input range is fine here. The wide range is also why many chargers work abroad with nothing more than a simple plug adapter, which is handy if you are packing one of our travel chargers. If a charger only lists a narrow range, such as 110–120V, it was designed for a different market and should not be used on UK mains without proper conversion.
The output rating: what the charger gives your phone
The “Output” line is the one that matters most when you are comparing chargers. It uses a different symbol: a solid line with a dashed line underneath (⎓), which means direct current (DC), the kind your phone battery actually uses.
A basic charger might simply say 5V ⎓ 2A. A fast charger usually lists several combinations, for example 5V ⎓ 3A, 9V ⎓ 2.22A, 12V ⎓ 1.67A. Each pair is a voltage and current the charger can supply, and your phone negotiates which one to use. To work out the power, multiply volts by amps: 9V × 2.22A is roughly 20W. Many chargers print the maximum wattage separately too, often written as “20W Max” or similar.
Chargers with more than one port sometimes show a separate rating for each port, plus a combined total. That total is shared between devices, so plugging in a second phone will usually reduce the speed of the first. If you regularly charge several things at once, it is worth reading the per-port figures carefully before choosing one of our multi-port chargers.
Fast charging labels: USB PD, PPS and QC
You may also spot short abbreviations near the port or in the small print. PD stands for USB Power Delivery, the widely used fast charging standard over USB-C that most recent iPhones and many Android phones support. PPS (Programmable Power Supply) is an extension of Power Delivery that allows finer voltage adjustments, and some phones need it to reach their top charging speed. QC refers to Qualcomm Quick Charge, which is found on some Android handsets.
These labels tell you which “languages” the charger speaks. If your phone and charger share a fast charging standard, you are far more likely to get the speed you expect. If they do not, the charger will normally fall back to a slower, basic rate. Browse our fast chargers and check the listed standards against your phone’s specifications.
Safety and conformity marks: UKCA and CE
The UKCA mark (UK Conformity Assessed) and the CE mark are the manufacturer’s declaration that the product meets the relevant safety and electromagnetic compatibility requirements. You will see either or both on chargers sold in the UK. The CE mark continues to be accepted for many products sold in Great Britain, so a charger showing only CE is not automatically a problem.
Be aware that these marks are self-declared and can be copied by counterfeiters. A mark that looks oddly spaced, smudged or badly printed is a warning sign, and it should never be the only thing you rely on. Buying from a reputable retailer and checking the overall build quality matters just as much.
The double square: double insulation
A small square inside a larger square is the symbol for Class II equipment, more commonly called double insulated. It means the charger has been built with an extra layer of insulation so that it does not need an earth connection to be safe. Almost all phone chargers are Class II, which is why the earth pin on a UK charger is often made of plastic: it is only there to open the shutters on the socket.
Indoor use and efficiency markings
A symbol shaped like a little house, or the words “for indoor use only”, means the charger is not designed to cope with rain or damp. Keep it away from bathrooms, outdoor sockets and anywhere it might get wet.
You may also see a Roman numeral, often VI, inside a circle or box. This is an energy efficiency level for external power supplies. Level VI is the current higher tier and indicates the charger meets tighter limits on wasted energy, including the small amount it draws when plugged in with nothing attached.
The crossed-out wheelie bin: recycle, don’t bin
A wheelie bin with a cross through it means the product falls under the WEEE (Waste Electrical and Electronic Equipment) rules and should not go in your household rubbish. Old chargers and charging cables can be taken to a local recycling centre or to a retailer take-back scheme so the metals and plastics can be recovered.
Using the markings to choose your next charger
When you are shopping for a new phone charger, a quick scan of the label answers most of the important questions:
- Does the input range include 230V? It should for UK use.
- Does the output wattage match or exceed what your phone can accept?
- Does it support the same fast charging standard as your phone, such as USB PD or PPS?
- Are the conformity and insulation marks present and cleanly printed?
Pair the right charger with a good-quality charging cable and you will get safe, reliable charging every day. When you are ready, take a look at our full range of wall chargers or browse everything in the shop.