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Look at any device charger, and you’ll find a listed power rating that details the maximum output voltage and current, like 5V 1A for 5 volts and 1 amp. Power bricks or larger laptop adapters usually list this information, too, as well as battery power packs and power stations. The reason is simply because this tells you the power matchup, or rather, the capabilities of the adapter and whether or not it will be compatible with your device. Certain devices, like those that need high power or fast charging, require more power — the Steam Deck is an excellent example. But there are some adapters that seem fairly close, like 5V 1A and 5V 2A, so which is the better choice for charging your devices?
The key to understanding the difference is that second number or classification. For both types of chargers, the 5V indicates the maximum voltage possible, which is the same. The second number — the 1A or 2A — indicates the consistent current supplied in amps. But in most cases, we want to know how many watts an adapter supplies. To find out, we multiply volts by amps. So, a 5V 1A charger delivers up to 5 watts (5V x 1A = 5W), versus the 5V 2A, which delivers up to 10 watts. Put in more practical terms, that means the 2A adapter would charge faster.
Note that it simply charges a little faster, but does not constitute true “fast charging” standards, which require a minimum of 9V or 18W and up. But when comparing the two directly (5V 1A versus 5V 2A), the latter is technically better, since it supplies more power and will charge compatible devices faster.
Neither charger type, 1A or 2A, offers true fast charging capacities
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You can still use either charger with your phone or devices, generally, but if you’re using a low-power option, like the 5V 1A charger, it will take longer than if you were using a stronger charger. You’ll also want to avoid using the device while it’s charging, unless the adapter you have supports high power and the Power Delivery (PD) standard. Interestingly, both the 5V 1A and 5V 2A charger types aren’t up to the PD standard, so if you want true fast charging, you should use something better.
Standard phone charging for modern devices is usually around 2.4 amps and 12 watts, with true fast charging from 9 volts or 2 amps and 18 watts. Comparatively, USB-C laptop charging often starts at about 20 volts or 3.25 amps and 65 watts. That’s actually a good illustration of why you probably shouldn’t charge your laptop with your phone’s USB-C charger. The USB-C connector makes them seem compatible, but it may not be practical in terms of the maximum power output, as phone chargers tend to deliver less power overall compared to something like a laptop power brick. This is also why it’s highly likely you’re using the wrong USB-C phone charger if you’re mixing and matching adapters and cables.
If you’re planning to charge your phone without carrying an actual charging adapter, like using your power bank or portable charging stations intuitively placed wherever you visit, it’s also important to pay attention to the power output capabilities of these systems. Not all power banks support fast-charging, nor do they all deliver enough consistent power for today’s devices. The same is true for charging stations you might encounter in the wild; those with built-in USB cables especially.
