How fast can I charge my Samsung Galaxy S21 with an old charger?

Without a charger in the box, the Samsung Galaxy S21 series has created a new headache for consumers. Paying extra for a new charger, sifting through the range of third-party options, or simply relying on an old plug you have laying around isn’t an easy choice to decipher. Especially given the perpetually confusing state of USB-C charging standards.

Before you rush out to buy a new charger, we’ve tested a selection of older smartphone plugs and a host of newer third-party chargers to help inform your decision. Here’s everything you need to know about buying the perfect Samsung Galaxy S21 charger.

Our review: Samsung Galaxy S21 Ultra review: Ultra refined

The best Samsung Galaxy S21 charger for fast charging

The entire Samsung Galaxy S21 range charges up with a maximum power rating of 25W. It achieves this through the use of the USB Power Delivery Programmable Power Supply (USB PD PPS) standard. This can also be obtained through compatibility with the Quick Charge 4+ standard. Specifically, the phone negotiates around 2.6 amps at 9.3 volts for a total of 25W of charging power.

As such, you can’t obtain this speed when using regular USB Power Delivery, Quick Charge 3.0, or various other charging standards.

The Galaxy S21 only charges at 25W using a USB Power Delivery PSS plug. Other plugs charge too, albeit slower.

Of course, Samsung sells chargers designed to charge up its latest smartphones. The company’s 25W and 45W Travel Adapters are USB PD 3.0 PPS compliant, but you won’t need the latter unless you plan to charge up the Galaxy Note 10 Plus, S20 Ultra, or a USB PD compatible laptop or tablet.

Learn more: Best Samsung fast chargers

If you’re in the market for a futureproof 45W PPS plug, you can spend less money and achieve the same results as Samsung with the Elecjet 45W. The Electjet 45W charger supports the required USB PD PPS charging modes and we have tested the phone to confirm it outputs the full 25W maximum power of the Galaxy S21. The Elecjet or one of Samsung’s official chargers are currently the best ways to charge the Samsung Galaxy S21 series at full speed.

Oddly, we also tested the PPS compliant Anker PowerPort III Pod 65W, but it does not fast charge the Galaxy S21. There’s possibly a profile issue that stops the two from exchanging power requirements, but this doesn’t build confidence that the USB PD PPS spec will help simplify the convoluted brochure of charging standards.

Can I charge the Galaxy S21 with my old Samsung charger?

If you already own an older Samsung charger, you may not need to buy a new one to quickly charge your Samsung Galaxy S21 smartphone. Samsung’s 25W Super Fast Charging and 45W Super Fast Charging 2.0 plugs support USB PD PPS and provide the full 25W supported by the Samsung Galaxy S21 series.

Samsung shipped its 25W Super Fast Charging plug with the Samsung Galaxy Note 10, Galaxy S20, and Galaxy Note 20 series of smartphones. You’ll need a pretty recent Samsung phone, but last-gen Samsung phones are already equipped with the best charger for the Galaxy S21.

Older Samsung chargers with a USB-A port marked Adaptive Fast Charging still work with the Samsung Galaxy S21 but won’t give you quite the fastest charging speed available. These plugs revert to Samsung’s Adaptive Fast Charge standard to provide 15W to the Galaxy S21 series. You find the Adaptive plug supplied with the Galaxy S20 FE, Galaxy S10 series, and older Samsung models.

Samsung’s older Adaptive Fast Charging plugs give you 15W of power, the same as newer USB PD and Quick charge accessories.

15W may not sound like a lot, but unless you spring for a USB PD PPS charger, 15W is the maximum power you’ll get from third-party plugs. We’ve tested a wide range of third party chargers with Quick Charge and USB Power Delivery support, and the Galaxy S21 will only pull 15W from these chargers too. So you might as well save some cash and stick with an old Samsung charger.

Further reading: Best USB C portable chargers

Charging the Samsung Galaxy S21 with old phone chargers

If you’re upgrading from another phone brand, the charging speed you’ll receive when trying to power up your new Samsung Galaxy S21 is much more hit and miss. We’ve tested chargers from Apple, Google, LG, Huawei, Xiaomi, and others. The table below isn’t a comprehensive list but reveals the key specs you’ll need to charge Samsung’s latest flagships quickly.

Phone Charger	Supported Universal Standards	Samsung Galaxy S21 Charging Power
Google Pixel Charger	USB PD (5V 3A, 9V 2A)	15W via USB PD 2.0
LG 16W Fast Charge	Quick Charge 3.0 Quick Charge 2.0 (9V)	15W via Quick Charge 2.0
Huawei 40W Super Charge	Huawei Super Charge Huawei Fast Charge Quick Charge 2.0 (12V)	9W
Huawei 66W Super Charge	Huawei Super Charge Huawei Fast Charge Quick Charge 2.0 (12V)	15W via Quick Charge 2.0
Realme VOOC Flash Charge 3.0		0.5W
Xiaomi 30W, 40W, and 120W adapters	Quick Charge 3.0 Quick Charge 2.0 (12V)	15W via Quick Charge 2.0
ZTE Quick Charge 3.0	Quick Charge 3.0 Quick Charge 2.0 (12V)	15W via Quick Charge 2.0

If you have an old phone charger that supports USB Power Delivery, Quick Charge 3.0, or Quick Charge 2.0, then it will charge up your Samsung Galaxy S21 with a maximum of 15W of power. Chargers that support proprietary fast-charging standards, such as those from Huawei and Realme, are less likely to support these universal standards and will default back to 9W or 5W charging, or might not even work at all.

Generally speaking, Chinese brands are more likely to support proprietary rather than the universal standards that the Galaxy S21 works well with. More familiar Western household brands like Google and LG work reasonably well with Samsung’s latest flagships.

The same rule of thumb applies to third-party accessories from Anker, Belkin, Aukey, and others. Plugs and ports that support USB Power Delivery, Qualcomm Quick Charge, and Samsung AFC all offer up to 15W of power to the Samsung Galaxy S21. Standard USB ports or those that support Apple’s 2.4A standard will fall back to 9W charging or slower.

Related: The best USB-C cables you can buy

Which adapter chargest the Samsung Galaxy S21 the fastest?

If you’re interested in the specific results from our Samsung Galaxy S21 charging test, check out the graph below for our full data set.

Based on our extensive testing, the only way to achieve the Samsung Galaxy S21’s maximum 25W of charging power is to use a USB Power Delivery PPS plug. However, even then it needs to support a 3.3V to 11V power profile to work correctly. So far, we’ve only identified three chargers that power up the Samsung Galaxy S21 at full speed. These are Samsung’s 25W and 45W Super Fast Charging plugs and the Elecjet 45W Super Fast Charging adapter.

Other third-party chargers typically achieve 15W of power, which is definitely slower but still reasonably useful. The Samsung Galaxy S21 charges at 15W over the USB Power Delivery, Quick Charge, and Samsung Adaptive Fast Charging standards. So there’s plenty of support for this speed out there from older phone plugs and third-party accessories. Just be aware that not every old phone charger or accessory will fast charge the Samsung Galaxy S21.