Design

Measuring in at 4.7 and 5.5-inches, the iPhone 6 and the iPhone 6 Plus dwarf earlier iPhone models, but at the same time, the two phones became Apple's thinnest yet, measuring in at 6.9 and 7.1mm, respectively. For comparison's sake, the iPhone 5s was 7.6mm thick.

According to Apple, the thinner profile was made possible by the company's "thinnest display yet," which is made of slightly curved glass designed to flow seamlessly into the body of the device to highlight the "Retina HD" screen of the iPhone 6 and iPhone 6 Plus.

Both devices include prominent antenna bands on the back enclosure, along with a protruding rear lens. The volume buttons are pill-shaped, much like the buttons on the iPad Air, and the power button has been relocated to the right side of the device.

The iPhone 6 measures in at 5.44 inches long and 2.64 inches wide, and weighs 4.55 ounces. The iPhone 6 measures in at 6.22 inches long and 3.06 wide, weighing 6.07 ounces. In comparison, the iPhone 5s is 4.87 inches long, 2.31 inches wide, and it weighs 3.95 ounces.

Retina HD Display

iPhone 6 rumors largely suggested Apple would use a sapphire display cover in the device, but that turned out to be false. Instead, the iPhone 6 and the iPhone 6 Plus use "ion-strengthened" glass with an improved polarizer (for better outdoor viewing), a photo aligned IPS liquid crystal display, and a fingerprint-resistant oleophobic coating.

The iPhone 6 has a 4.7-inch display with a "2x" resolution of 1334 x 740 (326 ppi) while the iPhone 6 Plus has a 5.5-inch "3x" resolution of 1920 x 1080 (401 ppi). Both phones are said to offer higher contrast, better brightness, and improved white balance.

According to a test conducted by DisplayMate, the iPhone 6 Plus display was the "best smartphone LCD ever tested" at the time. The iPhone 6 display also received high marks.

Apple has implemented several "Reachability" features in iOS to improve the viewing experience on its larger devices, including Display Zoom and landscape view (iPhone 6 Plus only). Display Zoom lets users zoom in to get a closer view at their apps, while standard zoom displays more content on the screen.

Landscape view on the iPhone 6 Plus is designed to make the most of the 5.5-inch screen and to help users be more productive. When in landscape mode, the device displays apps like Mail, Calendar, and Stocks in a wider view similar to the way they're displayed on the iPad.

The iPhone 6 and the iPhone 6 Plus take advantage of dual domain pixels, which improves viewing angles. AnandTech has given an in-depth overview of dual domain pixels, explaining that the technology alludes to the fact that the electrodes in the pixels are not all aligned. Instead, the pixels are "skewed when viewed from the perspective of the lines defined by the rectangular edges of the display," allowing them to compensate for uneven lighting.

Battery Life

The iPhone 6 and the iPhone 6 Plus both offer improved battery life, but due to the larger size of iPhone 6 Plus, it is able to accommodate a larger battery. The iPhone 6 has an 1,810 mAh battery, while the iPhone 6 Plus has a battery capacity of 2,915 mAh.

Because it has a bigger battery, the iPhone 6 Plus has a longer battery life than the smaller iPhone 6. 3G talk time for the iPhone 6 Plus is at 24 hours, compared to just 14 hours in the iPhone 6, for example, while HD video playback is at 14 hours for the iPhone 6 Plus and 11 hours for the iPhone 6.

Reviews of the iPhone 6 and 6 Plus suggested that the iPhone 6 can last up to a day and a half on average, while the iPhone 6 Plus can last up to two days on a single charge. A battery life test conducted by AnandTech showed the iPhone 6 and the 6 Plus beat out many competing Android devices, lasting longer than the Samsung Galaxy S5 and the HTC One M8. The iPhone 6 Plus had the second longest battery life of any device tested, coming in behind the Huawei Ascend Mate 2.

Despite shipping with a 1A/5W power adapter, the iPhone 6 and 6 Plus are capable of drawing up to 2.1A/12W of power, which means that iPhone users can likely obtain a faster charging time using an iPad adapter. According to early testing, charging with a 12W iPad adapter charges the iPhone 6 Plus in approximately two hours.

A8 Chip and M8 Motion Coprocessor

Both the iPhone 6 and the iPhone 6 Plus have an 64-bit A8 processor built on a 20-nanometer process by TSMC. Not only is the chip smaller than the A7 in the iPhone 5s, it's also able to deliver 25 percent faster CPU performance while being 50 percent more energy efficient.

The A8 takes full advantage of Metal, Apple's gaming technology that lets developers create console-style games on the iPhone. According to Apple, Metal is designed to let the GPU and CPU work together to provide detailed graphics and complex visual effects, which means gaming on the iPhone 6 and 6 Plus is going to be better than ever.

Alongside the A8, there's also an M8 motion coprocessor, which is the successor to the M7 motion coprocessor introduced in the iPhone 5s. The M8 measures data from the accelerometer, compass, and gyroscope, along with a barometer, which is new to the iPhone 6.

With the addition of the barometer, the M8 motion coprocessor can measure elevation in addition to steps taken and distance traveled.

AnandTech published an analysis of the A8 processor that points towards significant GPU enhancements and an enhanced Cyclone CPU at 1.4Ghz.

The iPhone 6 and 6 Plus have topped CPU benchmarking tests (compared to competing Android devices and the iPhone 5s), but the iPhone 6 Plus lags slightly in graphics performance due to the device's larger screen.

Camera Improvements

The iPhone 6 and the 6 Plus continued to sport an 8-megapixel f/2.2 rear camera, but the addition of several new features result in vastly improved picture quality. Continuing to offer improved camera capabilities has always been a priority for Apple, with the company even opting to include a protruding lens design to avoid making image quality sacrifices for the sake of the thin design of the iPhone 6 and 6 Plus.

The first major new feature, "Focus Pixels," was designed to speed up autofocusing by providing the sensor with more information about an image, while improved auto image stabilization compensates for slight amounts of motion blur and hand shakiness. Focus Pixels vastly speed up autofocusing times and improve autofocusing in low light situations, as demonstrated in a review of the iPhone 6 and 6 Plus cameras.

Both phones also included improved face detection capabilities and more control over exposure, and the Panorama feature added support for high-resolution panoramic photos of up to 43 megapixels.

Video options were improved in the two devices, making it possible to capture 1080p HD video at 60fps. There was also a new 240fps slo-mo mode, as well as time-lapse video, which was introduced with iOS 8.

The iPhone 6 Plus has one slight advantage when it comes to the camera, however, as it takes advantage of the M8 motion coprocessor to offer optical image stabilization. Optical image stabilization better compensates for hand shake and slight movements in low light than standard auto image stabilization techniques.

Along with rear camera improvements, the iPhone 6 and the iPhone 6 Plus featured improved front-facing FaceTime HD cameras with a new sensor and an f/2.2 aperture. With these improvements, Apple touted the front-facing camera could capture 81 percent more light, resulting in much better low-light photos. There was also a new burst mode for the front-facing camera, which let users take burst mode selfies for the first time.

In the DxOMark tests from reputable camera testers DxO Labs, the iPhone 6 and 6 Plus both scored an 82, overtaking the Samsung Galaxy S5 and the Sony Xperia Z2 as the best smartphone cameras in both the photo and video categories.

According to the testing, both the iPhone 6 and 6 Plus performed similarly, with the site noting that both had "very good, generally reliable auto-exposure" in a range of lighting conditions and fast, accurate autofocus.

The optical image stabilization in the iPhone 6 Plus, which was a differentiating factor between the two devices, resulted in better noise performance and less ghosting on HDR images, but it did create a video stabilization artifact that ultimately led to a better score for the iPhone 6 in the video category.

Connectivity Improvements

Apple's iPhone 6 and iPhone 6 Plus both offered faster LTE with support for LTE Advanced networks, reaching speeds of up to 150 Mbps, and they offered 20 LTE bands for better connectivity when traveling. A real-world speed test showed some impressive speed gains between the iPhone 6 and the iPhone 5s when LTE Advanced was available.

The devices also included support for Voice over LTE (VoLTE) which allows users to make higher-quality phone calls over LTE. VoLTE also allows users on CDMA networks like Verizon to use voice and data simultaneously for the first time. VoLTE requires support from both Apple and carriers, and several carriers have pledged to roll out support for the service.

In addition to cellular improvements, the iPhone 6 and the 6 Plus were the first of Apple's iOS devices to offer support for 802.11ac Wi-Fi. 802.11ac Wi-Fi is able to offer connection speeds that are up to 3 times faster than previous 802.11n networks. The speed improvements possible going from the iPhone 5s to the iPhone 6 Plus can be seen in the video below.

Finally, the iPhone 6 supported calls over Wi-Fi, which can result in higher-quality calls, especially in situations where a cellular connection is low. Calling over Wi-Fi is another feature that requires carrier support, but a number of carriers have rolled out that support for the iPhone.

Memory

iPhone 6 and 6 Plus teardowns revealed that both devices continued to offer the same 1GB of RAM found in the iPhone 5s.

Other Features

Like the iPhone 5s, the iPhone 6 and iPhone 6 Plus continued to offer Touch ID, Apple's fingerprint-based security system. Touch ID is used in place of a passcode on the iPhone, making it quicker to unlock the device and secure sensitive data within apps.

Touch ID is also an integral part of Apple's Apple Pay mobile payments initiative, as is the Near Field Communication (NFC) antenna built into every iPhone 6. Apple Pay is designed to allow users to pay for purchases at thousands of retail stores with just a fingerprint.

Operating System

The iPhone 6 and the iPhone 6 Plus initially shipped with iOS 8, the version of Apple's mobile operating system that debuted for older devices just days ahead of the iPhone 6 launch. As of September 2015, the iPhone 6 and 6 Plus began shipping with iOS 9.