Your smartphone may come with a standard-sized 1 meter USB cable in the box. But its length seems insufficient when your electrical outlet is far from your table or your bed. In such cases, purchasing a longer USB cable becomes necessary for convenience. Choosing the right cable is crucial, as longer, substandard cables have a reputation for slow charging speeds. They cannot provide adequate voltage despite using a fast charger and tend to malfunction more quickly. But does the increased cable length reduce the charging speed of your phone?
From a pure physics perspective, electrical resistance will increase with cable length, because resistance negatively impacts voltage. Your phone will undoubtedly charge slower with a longer USB cable than with a shorter cable. But the percentage drop is significant: if you use a one-meter USB cable and upgrade to a good-quality, certified two-meter USB cable, you’ll see a negligible drop in charging speed that’s hard to notice. However, cable length isn’t the only determining factor that affects your charging speed.
The caliber and certification of the USB cable is important
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Appearances can be deceiving, as a wire that appears very thick with a sturdy jacket might not be able to transfer current at the same rate. USB cables use AWG (American Wire Gauge), a standard that indicates the thickness of the wires inside the cable. Thick wires have less resistance and can minimize overall voltage drop over longer lengths. Since USB cables can do charging and data transfer, there is an AWG rating for each. For example, a 28/24 AWG USB cable means it uses 28 gauge (thin) wires for data transfer and 24 gauge (thick) wires for charging.
A lower AWG number means the wires inside the cable are thicker. Typically, you’ll find cheap USB cables that are 28/28 AWG, but you should avoid this gauge for longer cables. A 24 AWG USB cable will provide lower resistance than a 28 AWG cable and will provide constant voltage over longer lengths (two meters or more). So always choose the cable that clearly states the AWG on its body and its manufacturing label.
If you cannot find the AWG numbers on the web listing, product label or box, you need to check the cable certification. Usually, a certified cable will seek certification from the USB-IF (an organization that manages and develops USB standards) and list it on the box. USB-PD is also a common charging standard that trusted brands use to designate USB cables that support fast charging. These cables cost more because they use thick copper conductors, better connectors, and meet compliance standards.
