Unlike other handset makers, Apple rarely talks about battery capacity in raw numbers.

This was true when the iPhone 13 was unveiled at Tuesday's Apple event, where the company praised the handset's improved efficiency and larger cells, but only promised that it would last 90 minutes to 2.5 hours longer depending on the model purchased.

Given that the iPhone 12's battery was a serious weakness, the vagueness was frustrating, but fortunately, thanks to documents Apple published on Chemtrec's website (via 9to5 Mac), the actual numbers are known.

Although they are published in watt-hours (Wh) rather than the more common milliamp-hours (mAh), the figures serve to show which of Apple's promised improvements were brought about by the larger cells and which by the improved efficiency of the Apple A15 Bionic chipset It serves to show what the company's promised improvements are.

The iPhone 13 mini's battery is 9.34 Wh, a 9% increase from the iPhone 12 mini's 8.57 Wh. The iPhone 13 Pro Max battery, on the other hand, is nearly 20% larger, from 14.13 Wh to 16.75 Wh.

Curiously, the iPhone 12 and iPhone 12 Pro batteries were the same 10.78Wh, but the 2021 version is upgraded by a different amount. The regular iPhone 13 improved by 15.1% to 12.41Wh, while the Pro version improved by 11% to only 11.97Wh. Considering that the Pro model must also power the 120Hz screen, Apple's relatively modest projected power consumption of 90 minutes Apple's relatively modest power consumption of 90 minutes may also be explained.

But whether Apple's prediction is optimistic or pessimistic, and whether any of the iPhone 13 models will join the list of phones with the longest battery life.

However, given the iPhone 12's poor battery performance (especially when gaming), any improvement would be welcome. In fact, in a recent survey of 2,000 potential iPhone 13 buyers, improved battery life was the most desired upgrade, supported by 34% of respondents. In contrast, promised speed and camera improvements were only cited as priorities by 22%.

The iPhone 13 will be released on Friday, September 24, and is available for pre-order now. Below are the best pre-order deals we have found so far for the iPhone 13.