Charger boxes are covered in numbers: 5W, 20W, 30W, 65W, 100W. It’s easy to assume bigger is always better, or to worry that too much power will harm your phone. Neither is quite true. This guide explains what wattage really means and helps you match the right charger to your device without overthinking it.
What a “watt” actually measures
Wattage (W) is simply how much power a charger can deliver. More watts means more energy can flow per second, which generally means faster charging — up to the limit your phone is designed to accept. That last part is important: your phone, not the charger, decides how much power it draws. A 65W charger won’t force 65W into a phone that only accepts 20W; it will safely deliver 20W and no more.
Can a high-wattage charger damage your phone?
This is the most common worry, and the answer is reassuring: no. Because your phone only pulls the power it’s built to handle, using a higher-wattage charger than you need is perfectly safe. In fact, a more powerful charger can be a smart buy — it charges your phone at full speed and still has headroom for a tablet or laptop later. The real risk comes not from high wattage but from cheap, uncertified chargers with poor safety components.
How many watts your device needs
Here’s a simple rule of thumb. Phones: most modern phones fast-charge fully at 20–30W, and there’s little benefit going higher for a phone alone. A quality 20W fast charger is the everyday sweet spot. Tablets: larger batteries benefit from 30–45W. Laptops: typically need 45–100W depending on the model. Earbuds and smartwatches: draw only a few watts, so any charger will do.
Why your fast charger sometimes charges slowly
If you’ve bought a powerful charger but charging still feels slow, the bottleneck is usually the cable or the standard. Fast charging needs three things to line up: a capable charger, a cable rated for that power, and a phone that supports the same fast-charge standard (such as USB Power Delivery). A worn or low-quality cable will throttle even the best charger. If speeds disappoint, try a better cable first.
The bottom line
Don’t stress about the numbers. For a phone, aim for around 20W with a good cable and you’ll get fast, safe charging. If you also own a tablet or laptop, a 45–65W multi-port charger is a versatile choice that handles everything. Browse chargers by power and device in our shop, or read our fast charging explainer for more detail.