How the World Tells Time
Every country's default clock format on phones and operating systems, 12-hour vs 24-hour.
Every country’s default clock format on phones and operating systems, based on Unicode CLDR (the dataset every major OS uses to decide whether your lock screen shows 3 pm or 15:00). Two countries are split internally: Canada (English defaults to 12-hour, French to 24-hour) and Syria (Arabic 12-hour, Kurdish 24-hour).
Note that this differs from how residents in the countries may use time colloquially.