Does Apple Watch drain iPhone battery?

Modified Oct. 10, 2023, 8:40 a.m.


It’s a question all Apple Watch users asked themselves, I explain here all you need to better understand if the Apple Watch drains the iPhone battery.

Yes, the Apple Watch drains the iPhone battery, but only a bit. Many connections are made between the Apple Watch and the iPhone to share information, and each of them uses a bit of both battery.

The percentage of your iPhone’s battery the Apple Watch will drain depends on how you are using the watch, how many applications are on it, and how much workout you are doing.

I will first explain how much battery is used each time your iPhone needs to share something with the Apple Watch, and then how much data are shared between the devices. I also give a few tips to limit the Apple Watch from draining your iPhone battery.

How much power is used on a connection between iPhone and Apple Watch?

When the Apple Watch is near the paired iPhone and both devices have Bluetooth enabled, they are using Bluetooth to share information.

And since the release of Bluetooth 4.0 more than 10 years ago, Bluetooth connections are made using Bluetooth Low Energy technology, which has very low battery consumption.

When the devices are too far from each other to establish a Bluetooth connection, they will try to share information through Wi-Fi. Of course, it requires that both the Apple Watch and the iPhone are connected to the same SSID Wi-Fi gateway.

If Wi-Fi connections use more power than Bluetooth ones, there are not using too much power and therefore will not drain too much of your iPhone’s battery, as is well explained in this Apple forum discussion.

If neither Bluetooth nor Wi-Fi can be used, and if your Apple Watch can use cellular, then sometimes the devices will use the cellular connection to share information. But cellular connections are using more power than the two other ones, therefore you should try to avoid it whenever you can.

How much data are shared between an iPhone and an Apple Watch?

This is depending on how you are using your Apple Watch, as some applications are sharing more information with the iPhone than others.

All the applications related to sports, such as the Apple fitness app, will share much information with the iPhone so it can gather more data about your health and give you better advice. As these apps are sharing information, they are draining a bit more your iPhone’s battery, but those are very useful data and you don’t want to disable anything related to your health.

This is especially true when you first use an Apple Watch. Your iPhone will try to gather more information than usual to understand how good your health is, such as how is your walking or your average heartbeat.

Otherwise, here is a short list of events that trigger data shared between the Apple Watch and the iPhone:

  • Notification sent to your Apple Watch
  • Health data gathering
  • Remote iPhone control using the Apple Watch
  • Call and message made from the Apple Watch
  • Any actions made on the Apple Watch that require syncing with the iPhone, such as timers.

5 ways to limit the Apple Watch from draining your iPhone battery

Limiting the Apple Watch from draining the iPhone battery will not only help to see the phone battery lasting longer but will also increase both the iPhone and the Apple Watch's battery life, and preserve the battery health.

You can check your Apple Watch battery cycle count using the same way as the iPhone battery cycle count.

Enable Bluetooth

As explained above, Bluetooth connections are very power efficient nowadays. Be sure that Bluetooth is enabled on both devices so they can use it when near each other.

Enable Wi-Fi

Enabling Wi-Fi on both devices ensures that they are not using the cellular network to share information. Wi-Fi is way more power efficient than cellular, especially if the cellular network is not good at your location.

Reduces the number of applications

Try to remove all the applications you are not using on the Apple Watch. Each application can potentially share information with the iPhone and therefore drain a bit more of the iPhone’s battery. If there are too many apps on the Apple Watch, the watch drains power.

Reduces the number of notifications

You can choose which of your applications is allowed to send any notification to the Apple Watch, try to select only the applications you want to see the notifications on your Apple Watch. To do so, go to the Watch app on your iPhone, and disable or enable the notifications under “Mirror iPhone alerts from”.

Be patient

If you just bought your first Apple Watch, it’s normal to see further battery drain, more than usual. A lot of data are gathered by your iPhone in the first months, be patient and it should get better.


Apple Watches are not draining iPhone batteries that much, and there are a few things you can try to limit the battery drain, and increase the battery life. It's not the main reason why iPhone batteries' health drops over time.

Apple is consistently improving the Apple Watch series, and new technologies are coming out. Apart maybe from the Apple Watch ultra, which is different from the other Apple Watches, using the last of them will also limit the Apple Watch draining effect.

If you think that your iPhone's battery does not last long and is out of warranty, you should replace it. Here are the best replacement batteries for your iPhone.

To learn more about iPhone batteries, here are 7 questions answered.



Maxime Levesque is a technical engineer with more than 5 years of professional experience. He is an expert in computer and phones, mostly on Apple products. Maxime is also the founder of TechBrowser.

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