PickGlobeChargers, cables and power banks look almost identical in photos, but the numbers behind them decide whether your devices charge quickly and whether the thing is safe to leave plugged in. Here's how to read a listing.
Watts are what matter for speed
A charger's output is measured in watts (W). Watts are volts multiplied by amps, so a listing may show something like "5V/3A, 9V/3A, 20V/3A" instead of a single number. The highest combination is the maximum the charger can deliver.
- Check what your device can accept. A device only draws what it supports, so a bigger charger won't charge it faster than it allows.
- Laptops need more. Small phone chargers may charge a laptop very slowly or not at all. Check the wattage on its original charger.
- Multi-port chargers share their power. A charger advertised at a high wattage may split that total between ports when several devices are plugged in. A good listing shows how the power is divided.
USB-C and Power Delivery explained
USB-C is the connector shape. USB Power Delivery (USB PD) is the open charging standard that lets a charger and device agree on a higher voltage for faster charging. Many phones, tablets and laptops use it, but not all, and some devices also use their own fast-charging methods.
When you shop, look for:
- "USB PD" or "Power Delivery" named in the specifications, along with the wattage.
- Support for your device's charging method if it uses something other than USB PD. If the listing doesn't say, assume it falls back to slower standard charging.
Cables are rated too
A cable can limit charging just as much as a charger.
| What the listing says | What it usually means |
|---|---|
| 60W or 3A | Fine for phones, tablets and many smaller laptops |
| 100W or 5A | Needed for higher-wattage laptops; these cables contain a small chip (an "e-marker") that tells the charger they can handle it |
| 240W | The newer extended-power level for the most demanding devices |
| USB 2.0 / USB 3.x / USB4 | Data speed, which is separate from charging power |
A cable rated for high power isn't necessarily fast for data, and vice versa. If you need both, check both numbers.
Power bank capacity: mAh vs Wh
Power banks are usually advertised in milliamp-hours (mAh), but that figure is measured at the internal battery's voltage, not the voltage your device charges at. Some energy is also lost in conversion, so you'll never get the full advertised capacity into your phone.
Watt-hours (Wh) is the more useful number, especially for travel. You can estimate it from the mAh figure: multiply mAh by the battery voltage (often shown on the label, typically around 3.6–3.7V) and divide by 1,000.
Flying with a power bank
Airlines and aviation authorities set limits on spare lithium batteries, and they're usually expressed in Wh, not mAh. Rules commonly include:
- Power banks go in carry-on (hand) luggage only, never checked (hold) baggage.
- Smaller batteries are generally allowed, while larger ones may need airline approval or may be refused.
- Some airlines limit how many you can carry or whether you can use them on board.
Rules differ between airlines and change, so check your airline's current policy before you fly. A Wh rating printed on the casing makes security checks easier.
Safety marks, in plain English
Mains chargers carry marks that show what standards the maker says they meet:
- UL (US): shows the product was tested by an independent safety organisation. Look for "UL Listed" or a similar certification, not just the letters in a description.
- CE (EU) and UKCA (UK): the manufacturer's declaration that the product meets the relevant safety rules for that market. They're required, but self-declared, so they're a minimum, not a seal of quality.
- FCC (US): relates to radio interference, not electrical safety.
A missing mark on a mains charger sold for your country is a reason to walk away.
How to avoid counterfeits
Fake chargers and cables are common, and the risk isn't just poor performance: badly made chargers can overheat.
- Be wary of prices far below the norm. See our guide to comparing prices across stores.
- Buy from the manufacturer's own store or an authorised retailer when a listing claims to be an original accessory.
- Check the seller, not just the product. On marketplaces, look at who actually ships it, and check the store is legit.
- Read reviews carefully. Look for comments about heat, packaging and markings, and learn how to spot fake reviews.
- Check on arrival. Spelling mistakes, flimsy plugs or missing marks are warning signs; stop using it and ask for a refund.
If you're ordering from another country, plug shapes and voltage matter too; see buying electronics from abroad.
The short version
Match the charger's watts to what your device accepts, look for USB PD and a cable rated for the power you need, judge power banks by Wh rather than mAh, check your airline's battery rules before flying, and buy mains chargers with proper safety marks from sellers you trust.