Which? said it compared an iPhone 7 running iOS 10, the latest release of Apple's mobile operating system, with the other three smartphone which were running version six of the Android mobile operating system, otherwise known as Marshmallow. (The latest Android release, version seven, is known as Nougat).
When tested with a 3G connection, the iPhone 7 provided 712 minutes of call time. The time for the HTC 10 was the most (1859) while the LG G5 lasted 1579 minutes and the Samsung Galaxy S7 1492 minutes.
Which? also tested the four smartphones to see how long they would last when used on the Web. The HTC 10 was again top (790 minutes), with the Samsung Galaxy S7 (677), the LG G5 (640) and the iPhone 7 (615) bringing up the rear.
Which? said it carried out the tests using its own phone network simulator to ensure that the signal strength was consistent for each test.
"(This) is important as a phone has to expend more power when it’s struggling for reception. We also set the screen brightness on every phone to the same level. Finally, we perform a full ‘power cycle’ of each phone’s battery prior to testing – that means fully discharging and then charging it," Which? said.
"For the tests we made a continuous call over 3G for the call time test and accessed a regularly updating special web page over 3G to measure Web browsing time."
In a related article, The Guardian's review of the iPhone 7 has posed the question, "how good can a phone be if the battery doesn't last even a day?"
Which? is Britain's oldest consumer group, having been set up in 1957.