Timezone Converter
Convert times between any two time zones around the world.
How Time Zones Work
The world is divided into 24 primary time zones, each roughly 15° of longitude wide (360° ÷ 24 hours). The reference point is UTC (Coordinated Universal Time), formerly called GMT. Time zones are expressed as offsets from UTC: EST is UTC−5, PST is UTC−8, CET is UTC+1.
Daylight Saving Time
Many countries "spring forward" in spring (add 1 hour) and "fall back" in autumn (subtract 1 hour). Not all countries observe DST — Japan, China, India, and most of Africa do not.
Frequently Asked Questions
What is the difference between UTC and GMT?
For everyday practical purposes, UTC and GMT are the same — both represent the time at 0° longitude. The technical difference is that GMT is a time zone (based on astronomical observation) while UTC is a time standard (based on atomic clocks, adjusted with leap seconds to stay within 0.9 seconds of GMT). In practice, they are interchangeable for time zone conversion purposes.
Does all of the US change clocks for DST?
No. Arizona (except the Navajo Nation, which observes DST) does not change clocks — it remains on Mountain Standard Time year-round. Hawaii also does not observe DST. US territories including Puerto Rico, Guam, the US Virgin Islands, American Samoa, and the Northern Mariana Islands do not observe DST either.
Why do some countries have half-hour or 45-minute time zones?
Most time zones are offset from UTC by whole hours, but several use fractional offsets for geographic, political, or historical reasons. India (UTC+5:30) and Sri Lanka (UTC+5:30) use half-hour offsets. Nepal uses UTC+5:45. Iran uses UTC+3:30. Australia's Northern Territory and South Australia use UTC+9:30. These reflect attempts to align time zones with local solar time more accurately than whole-hour offsets allow.
How do I schedule a meeting across time zones?
Find a time that falls within business hours for all participants. A useful approach: first convert everyone's local business hours (typically 9 AM–5 PM) to UTC, find the overlap in UTC, then convert back to each person's local time. Online tools and calendar apps like Google Calendar make this easier by showing event times in each participant's local time zone automatically when you invite them.
What is the International Date Line?
The International Date Line is an imaginary line roughly following the 180° meridian (on the opposite side of Earth from the Prime Meridian in Greenwich). Crossing it westward advances the calendar by one day; crossing it eastward moves the calendar back one day. It zigzags to avoid splitting countries and island groups between two dates. This is why it is possible to travel west from the US and arrive in Japan on a different calendar day than when you departed.