Which is better for watching video while charging?

The 633. Its stand folds out and holds the iPhone upright, so you can watch or take calls hands-free. The 621 lies flat with no stand.

Which charges faster?

The 621 has the higher wireless peak at 12W versus 7.5W on the 633. Over the cable, the 633 wins at 15W versus 12W.

Can either charge two devices at once?

Only the 633. It charges the iPhone wirelessly and a second device through its USB-C port. The 621 handles one device at a time.

Which is easier to carry?

The 621. At 0.45 inches thick with no hinge, it slides into a pocket flat. The 633 is thicker because of its stand.

Is the 633 worth the extra money?

If you want the stand and the second-device port, yes. If you only need a flat MagSafe top-up, the 621 does that for less.

Do both work with MagSafe iPhones?

Both are magnetic MagSafe batteries for iPhone. The 621's listing names iPhone 13 Pro and iPhone 12; the 633 lists iPhone generally.

Anker 633 Magnetic Battery vs Anker 621 Magnetic Battery

Buy the Anker 633 if you want a stand that holds the phone up and can charge a second device over USB-C. Buy the Anker 621 if you want the smallest, lightest MagSafe pack that snaps flat to the back of the phone. The 633 is the more flexible battery; the 621 is the more pocketable one. Check the live prices on both before you decide, since the gap between them moves.

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