> They advertise the 633 to hold 1.3 charges for an iPhone 13.

I think you have a typo there. The product page for 633 says 1.8 charges for the iPhone 13.

I was confused why 60% extra would seem low for half capacity of 1.3 charges (130%). Dividing 130% by two gives 65%.

But since it’s actually 180%, I agree that 60% extra seems low. Should have been about 90% extra one would think.