How can I set my iPhone clock to 24 hour / military time?

If you want to change the clock on your iPhone’s lock screen so that it always shows 24 hours, here are instructions.

1. Navigate to Settings -> General -> Date & Time

2. Select 24-Hour Time -> ON

Now your lock screen clock, as well as any time functions on your iPhone including World Clocks, Alarms, and the like will all display 24-hour time. To switch back to 12-hour time with AM and PM just tap 24-Hour Time -> OFF in the Settings.

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