How many time zones are there in the world?
There are 24 standard time zones in theory, one for each hour of the day. In practice, there are about 38 local time zones, because some countries use half-hour or 45-minute offsets.
The Earth turns 360 degrees in 24 hours, or 15 degrees an hour, so the world can be divided into 24 bands of 15 degrees each. Time zones are measured as offsets from Coordinated Universal Time, or UTC, ranging from UTC−12 to UTC+14.
Countries set their own time, so borders often zigzag. India uses a single zone of UTC+5:30, Nepal uses UTC+5:45 and parts of Australia use half-hour offsets. Some countries also switch to daylight saving time in summer.
Countries with many zones
France has the most time zones of any country, 12, because of its overseas territories around the world. Russia spans 11 time zones. China, despite its huge size, uses a single time zone for the whole country.
Did You Know?
Standard time zones were adopted in the United States and Canada by railroads in 1883, to replace confusing local times based on the position of the Sun in each town.