What is the battery life of the iPhone 4 in "real-world" tests? Is the battery replaceable?

Apple formally reports that the iPhone 4 (GSM) provides 40 hours of audio playback, 10 hours of video playback, 14 hours of talk time on 2G, 7 hours of talk time on 3G, 10 hours of Wi-Fi internet use, 6 hours of 3G internet use, and 300 hours of standby time. The reported battery life for the iPhone 4 (CDMA) is the same, except that it does not support a 2G network and consequently is limited to the same 7 hours of talk time on a 3G network as the GSM model.

Official Battery Life Comparison

With the exception of video playback and standby time -- which is the same for both the iPhone 4 and the iPhone 3GS -- the official battery life numbers for the iPhone 4 reflect a consistent across the board improvement compared to its predecessor:

	iPhone 3GS	iPhone 4
Talk Time (3G):	5 Hours	7 Hours
Talk Time (2G):	12 Hours	14 Hours*
Battery Life (Web - 3G):	5 Hours	6 Hours
Battery Life (Web - Wi-Fi):	9 Hours	10 Hours
Battery Life (Music):	30 Hours	40 Hours
Battery Life (Video):	10 Hours	10 Hours
Standby Time:	300 Hours	300 Hours

* The iPhone 4 (GSM) 14 hours of talk time on 2G, but the iPhone 4 (CDMA) does not support a 2G network.

Third-Party Battery Life Test Results

However, in addition to the general risk of "optimism" from manufacturers, third-party tests provide a better estimate of battery life in the "real-world" under actual usage conditions as most people tend to use their mobile devices for multiple tasks over the course of the day.

Those blessed with iPhone 4 devices prior to its public launch generally found the battery life solid in day-to-day use.

In the first review to hit the web, the WSJ's Walt Mossberg noted:

I didn't perform a precise battery test, but, even in heavy use, the iPhone 4's battery never reached the red zone on a single day of my tests.

In an in-depth review, Engadget's Joshua Topolsky reported:

The battery life on the iPhone 4 has been outstanding thus far, exceeding our expectations for longevity during testing. We've only had a short time to use the phone, but in the week or so we've been carrying the device as our main phone, we've had pretty amazing results under normal to heavy use. In fact, we managed to squeeze more than 38 hours -- yes, 38 hours -- of life out of a single charge using the phone as we normally would. We're talking calls, some gaming, lots of push email and calendar invites, playing music over Bluetooth in the car, and just general testing (like downloading new apps, rearranging icons, tweaking settings).

BoingBoing's Xeni Jardin, likewise, was impressed by the battery life results:

With light use, but with 3G data and WiFi turned on the whole time, I got a full 4 days of battery life. With very heavy video recording and playback, instant messaging, email and data tethering over 3G, I got a full day of battery life.

However, USA Today's Ed Baig did manage to use the iPhone 4 enough in a single day to reach a "low battery" warning:

Pounding it pretty hard, I still sometimes reached low-battery warnings late in the day, so having chargers where you work as well as where you live isn't a bad idea.

When this Q&A was first published on June 23, 2010, EveryiPhone.com noted that when more in-depth testing was available, these results would be added should they provide additional insight. Sure enough, the results from more detailed testing proved to be worthwhile. Although reviewers continued to be highly satisfied, they are a bit more measured in their praise as well.

In its trademark gigantic review, ArsTechnica found:

The first test we tried was a general use test aimed at simulating how most people use their phones in an average day. . . You usually do a few calls, post some tweets, maybe catch a YouTube video or two, put it down for a while to work, answer a text from your kid, check Yelp for a review of that one restaurant, put it down again, listen to music for a couple hours, read Ars, etc.

We did all of the above activities on and off for a full day, took the iPhone along on a night out with friends, and didn't plug it in overnight. Doing all this (which I would categorize as moderately high usage, but not insanely high), the phone lasted almost exactly 25 hours on a full charge. Based on our regular experiences with both the original iPhone and the 3GS, this basically falls in between.

AnandTech's Anand Lai Shimpi was highly satisfied with the battery life of the iPhone 4, finding it to be "incredible" in in-depth tests that definitely should be reviewed in their entirety, but he also concludes:

Early reports of 20 and 30 hours of battery life are simply exaggerated. They're only possible if you let the phone idle in your pocket for the majority of that time. In other words, if you don't use the phone it lasts for a long time. While that's a testament to the platform's incredible idle power, the real world usage is good enough to stand on its own. It's better than any iPhone or Android phone I've tested thus far.

iLounge -- which always is quite objective and was highly critical of the battery life of the iPhone 3G and iPhone 3GS -- is pleased with the battery life improvement of the iPhone 4, but still would like it to be better for phone calls specifically:

As a general rule, iPhone 4 will require less mid-day charging as a multipurpose device than the iPhone 3G and 3GS -- a very welcome though not ideal return to the calling battery life of the original iPhone, with considerably more power under the hood in this newer model. While further battery improvements are still needed, the option to stretch iPhone 4's life by switching to EDGE for calling purposes does exist, expanding the promised calling time to 12 hours. We don't recommend actually doing this due to its negative impact on iPhone 4's numerous data features, but it’s an option.

In a detailed follow up review for the iPhone 4 (CDMA) model, iLounge found that battery life was "virtually identical" to the GSM model.

Battery Self-Replacement Possibility

In its customary teardown, iFixit discovered that the battery is relatively easy to replace although it is not "swappable" or intended to be replaced by the end user.

However, unscrewing two screws on the bottom of the iPhone releases the back panel and the 3.7V 1420 mAh Li-Polymer battery is readily accessible. Thankfully, the battery is not soldered in place, either, so replacement is quite possible for the technically inclined equipped with the proper screwdrivers.

Battery Life & Replacement Summary

Ultimately, the consensus from both initial and more in-depth "real-world" usage tests is that the iPhone 4 is a significant improvement compared to earlier iPhone models and is suitable for "all day" use for many. Although some may wish that the battery was "swappable" as well, at least it is fairly easy to replace.

Site sponsor Mission Repair offers 24-hour by mail battery replacement, as well as other repair services, for all iPhone models.

Also see: How do I replace the battery in the iPhone 4?