Charging speed is a major selling point for new devices and accessories, and one way to speed things up is with a USB-C charger. These days, USB-C to USB-C cables are common, and they are known to generally charge devices faster than older USB-A cables. However, this does not apply to USB-A to USB-C cables, which (apart from some special cases) are incapable of quickly charging connected devices. The USB-A half of the cord limits its speed.
These ports max out at around 2.5 watts for USB 2.0 and 15 W for USB 3.0, a result of standards introduced in 2000 and 2008 respectively. This is slow compared to USB-C, which can reach up to 240 W, but it’s important to note that not all USB-C cables charge at the same speed and most have a maximum power rating well below 240 W. A good USB-A to USB-C cable will still charge your phone efficiently, but for true fast charging you’ll need a USB-C to USB-C cable. However, this is not the only factor that affects loading speed.
How fast charging works
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Three things impact fast charging: the cable, the adapter, and the device itself. The slowest of the three determines the charging speed, so in addition to a USB cable capable of fast charging, you’ll need a sturdy brick. Of course, this doesn’t matter much if your hardware can’t take advantage of it. Most smartphones only need around 20-30W, although newer and higher-end models like the iPhone 17 Pro, Samsung Galaxy S26, and OnePlus 15 are capable of 40-100W with the right equipment.
While you may not need an exceptionally powerful charger for your devices, using it won’t cause harm because it will only take what it needs. That said, while fast charging is generally safe, you need to keep an eye on your device to make sure it doesn’t get too hot. Some heat is normal, but excessive heat will damage the battery. This is a particular risk with cheap USB cables, which are not designed with safety features that can slow or stop charging to prevent overheating.
