https://wccftech.com/apples-magsafe-battery-pack-has-a-1460mah-capacity/

Although it gives you a ton of convenience, the newly announced MagSafe Battery Pack has a measly 1,460mAh capacity inside.

Don’t let that small capacity bother you, though. Apple has not been too generous whenever it comes to external battery packs for the iPhone. In fact, the iPhone XS Smart Battery Case had a total capacity of 1,369mAh, which is way less than what Apple has announced today for the iPhone 12 lineup in the MagSafe Battery Pack.