To answer that question, we took our trusty thermometer in hand and ran a series of tests that pitted Apple's latest tablet against the iPad 2 and two popular Android tablets--the Asus Eee Pad Transformer Prime and the LTE version of the Samsung Galaxy Tab 10.1.
Our results are likely to be reassuring to any potential iPad purchasers. Though the new iPad did run hotter than the iPad 2, the difference wasn't great. And in repeated lab tests of the new iPad, we could not replicate the disturbingly high temperatures that some sources have reported. More important, the new iPad was not dramatically warmer than either the Asus Eee Pad Transformer Prime or the Samsung Galaxy Tab 10.1 LTE, even though its battery has a substantially higher milliampere-per-hour (mAh) rating than theirs do (11666mAh for the new iPad, versus 7000mAh for the Galaxy Tab 10.1 and 6930mAh for the Transformer Prime).
Though our tests do not definitively address the question of whether the hotter temperatures pose a risk to the iPad's longevity, they do suggest that any heightened sense of alarm on the part of users and prospective users is unwarranted. Many mobile devices get toasty--and often much hotter than the top temperature of 100 degrees Fahrenheit that we recorded on the new iPad. For instance, a quick in-office test of a three-year-old aluminum Macbook laptop running basic office tasks registered 108 degrees Fahrenheit; and an on-lap Toshiba Portege R700, after running for about 30 minutes, clocked in at 112 degrees.
How We Tested
Using a Raytek Raynger ST-Handheld Infrared Thermometer, we took multiple temperature readings on both the front face and the back of each tablet, measuring the temperature at the tablet's center, at the charging port, and on the back. We took a set of baseline readings (not reproduced in the chart below) when the tablet was turned off; another set of readings when the tablet had been on but idle for 5 to 10 minutes; and a third set when the tablet had been on for 1 hour while continuously playing Vector Unit's graphics processor-intensive Riptide GP game. We kept Wi-Fi on throughout the testing, and the room's ambient temperature was comfortable and controlled. We conducted the series of tests first with each unit plugged in and charging, and then with each unit running solely on battery power.
The test results were consistent with our casual experiences while using these tablets: The Raytek thermometer revealed that each tablet has its own particular hot point, and that in some instances a tablet's front can be just as warm as its back. In addition, we noted that temperatures tended to run higher when tablets were plugged in than when they were running on battery power.
New iPad vs. Old
When turned off but charging, the new iPad registered a temperature of 76 degrees Fahrenheit on the back center of the tablet. The temperature at that same spot rose to 86 degrees after the device had been on for 5 to 10 minutes but idle; the maximum-heat spot on the back registered at 92 degrees under these conditions. After playing Riptide GP for 1 hour, the tablet had a maximum temperature reading on its back of 100 degrees Fahrenheit (94 degrees at the back center). Though Consumer Reports and other outlets reportedly recorded temperatures as high as 116 degrees, we were unable to push the new iPad's temperature beyond the century mark.
As you can see from the chart above, the new iPad ran between 5 and 7 Fahrenheit degrees hotter than the iPad 2 after playing Riptide GP for an hour while plugged in, and it was as much as 8 degrees hotter than the iPad 2 after playing the game for an hour on battery power alone. That behavior wasn't consistent across the board, however; on some of our tests, the new iPad, when running on battery power, was as little as 2 degrees warmer than the iPad 2. In general, the new iPad tended to run a bit warmer while charging, but not significantly so.
How Asus and Samsung Stack Up
The new iPad's heat profile is comparable to the heat profiles of the two Android tablets we tested: the Asus Eee Pad Transformer Prime (running Android 4.0) and the Samsung Galaxy Tab 10.1 4G LTE from Verizon.
While charging and after being on but idle for 5 to 10 minutes, the center of the Galaxy Tab 10.1's front face was 3 degrees cooler than that of the new iPad under the same conditions (77 degrees versus 80 degrees Fahrenheit); the difference jumped to 8 degrees when we measured the temperature on the back center of each tablet under those same conditions (78 degrees versus 86 degrees). At the maximum heat spot on each tablet, however, the difference narrowed to 2 degrees, with the iPad running at 92 degrees and the Galaxy Tab 10.1 at 90 degrees.
After 1 hour of game play, the front center of the Galaxy Tab was 9 degrees cooler than that of the new iPad under the same conditions (80 degrees versus 89 degrees), and the back center was 14 degrees cooler (80 degrees versus 94 degrees). But that delta again dropped to just 2 degrees when we compared the two tablets at their maximum hot points on the back (98 degrees for Samsung versus 100 degrees for the new Apple). Bottom line: Like the iPad, the Samsung got warm while simultaneously charging and running our test game, reaching a summery 98 degrees at its hottest point.
The Asus tablet proved to be a somewhat cooler customer. After playing Riptide GP for an hour while plugged in and charging, the Transformer Prime's temperature at its hottest spot topped out at 95 degrees Fahrenheit--1 degree above the iPad 2's maximum, but 5 degrees cooler than new iPad. When running on battery power, the Transformer Prime registered 91 degrees on that same test, versus 97 degrees for the new iPad.
iPad Taking Lots of Heat
Despite all of the media attention over the iPad's (and other tablets') operating temperatures, the issue seems to be overblown. None of the four tablets we tested ever get so warm that I could detect screen discoloration, of the type that some users of early units of the iPhone 4 reported. Given that the new iPad's battery has an mAh rating nearly double that of the batteries on the other tablets here, we would expect it to run at least a few degrees hotter than those units.
Other factors can significantly affect a tablet's temperature, as well. Asus's Transformer Prime, Apple's iPad 2, and the new iPad all have metal backs, which pull heat away from the internal components, whereas the Samsung Galaxy Tab 10.1 has a plastic back. All four tablets get warmer when their brightness is set to maximum. And all will get warmer still if they are sitting in a case or are parked on an insulating surface such as a blanket or your jeans. In one memorable past episode, a Transformer Prime got fry-an-egg hot when I left it inside a foam case with its screen on for an extended period.
If you're looking for some practical solutions to tablet heat problems, let good sense be your guide. Be aware that both a tablet's front and back surface can get warm, and try to avoid situations that might make them even warmer. If you do use your tablet to the point where it becomes uncomfortably warm, dial down the display's brightness for a while, or take a short break and give the tablet a chance to cool off a bit. Your eyes--and maybe even your lap--will thank you.