The main reason expensive smartwatches like the Apple Watch Ultra and Samsung Galaxy Watch Ultra are popular is clearly the battery life.

While you can get two to three days on a single charge with the Ultra models, the regular versions only last around a day or a day and a half. And if you want to track your sleep, this means that you have to carefully plan your charging routine.

But how much time do you need to fully charge these smartwatches? And is a 15-minute top-up enough?

As we are wrapping up our review of the Galaxy Watch 8 and Watch 8 Classic, we thought this is the perfect opportunity for the ultimate smartwatch charging test.

Charging Test Setup

For this charge speed test, we had eight smartwatch models that you will see listed below:

We carefully drained all of them, paired them up with the provided cables and proper charging bricks, and started the charging process.

Unfortunately, the test failed on two of those. The OnePlus Watch 3 43mm model failed because of our own mistake, while the Apple Watch Ultra 2 had a very strange result despite us using the proper charging cable and charging brick (we have to re-do this one). So we were left with six smartwatches and some very interesting charging speed results.

How do charging speeds compare?How much time do you get in 15 minutes?

ModelPercentage charged
in 15 mins Samsung Galaxy Watch 8 Classic 23% Samsung Galaxy Watch 8 (40mm) 22% Samsung Galaxy Watch Ultra 20% Apple Watch Series 10 (46mm) 22% OnePlus Watch 3 (46mm) 49% Pixel Watch 3 (45mm) 22%

As you can see, if you just leave your watch for a quick 15-minute top-up, you won’t see much of a difference in the charge percentage gained between devices.

Five of the smartwatches get 20% to 23%.

The big exception here is the OnePlus Watch 3 (46mm). This watch charges remarkably quickly. Not only is it the one with the longest battery life, it also gives you nearly half the battery life back in just 15 minutes. Impressive!

30-minute charge level check-in

ModelPercentage charged
in 30 mins Samsung Galaxy Watch 8 Classic 41% Samsung Galaxy Watch 8 (40mm) 45% Samsung Galaxy Watch Ultra 36% Apple Watch Series 10 (46mm) 50% OnePlus Watch 3 (46mm) 80% Pixel Watch 3 (45mm) 50%

Leaving the smartwatches on the charger for a bit longer shows bigger differences.

The Galaxy Watch Ultra is slowest, but that is kind of expected given its extra-large battery. However, the Galaxy Watch 8 and Watch 8 Classic are much slower to charge compared to the Apple Watch Series 10 and the Pixel Watch 3. We definitely hoped for faster charging speeds from Samsung, but no such luck.

Once again, the odd one out is the OnePlus Watch 3 which gets an impressive 80% of its battery back in just half an hour.

45-minute check-in

ModelPercentage charged
in 45 mins Samsung Galaxy Watch 8 Classic 60% Samsung Galaxy Watch 8 (40mm) 70% Samsung Galaxy Watch Ultra 52% Apple Watch Series 10 (46mm) 81% OnePlus Watch 3 (46mm) 99% Pixel Watch 3 (45mm) 79%

On this next check-in, we again see the Galaxy Watch lag behind rivals in an even more noticeable way. The larger Watch 8 Classic model, specifically, is 20 percentage points behind the Apple Watch Series 10 and the Pixel Watch 3.

And the OnePlus Watch 3? Well, it’s practically fully charged in just 45 minutes. We really wish 

Total Smartwatch Charging Time test results

ModelTime to a full charge Samsung Galaxy Watch 8 Classic 1 hour 24 minutes Samsung Galaxy Watch 8 (40mm) 1 hour 19 minutes Samsung Galaxy Watch Ultra 1 hour 48 minutes Apple Watch Series 10 (46mm) 1 hour 13 minutes OnePlus Watch 3 (46mm) 47 minutes Pixel Watch 3 (45mm) 1 hour 23 minutes

The conclusions are clear: Samsung’s Galaxy Watch 8 and Watch 8 Classic charging speeds are clearly behind the competition. We really wish Samsung improved this. Having a smartwatch with one-day battery life and slow charging is just not a good look.

Both Apple with the Series 10 watches and Google with the Pixel 3 series support slightly faster charging. And even though the difference is not night and day, it’s noticeable. For a gadget that you have to top up every day, having faster charging seems very important.

We also have to congratulate OnePlus on the incredible charging speeds we see from the OnePlus Watch 3 series. This watch is clearly the winner of this test. The OnePlus Watch 3 not only lasts multiple days, but it also charges much faster too. It uses a proprietary charging system, but if it can get such amazing results, maybe other companies should take notes.

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