Time Zone Converter: How to Convert Between Time Zones
Time zones govern when the world works, sleeps, and meets. Understanding how they work makes scheduling across continents straightforward.
How Time Zones Work
The Earth rotates 360 degrees every 24 hours, or 15 degrees per hour. Time zones divide the world into regions that share the same local time, each offset from Coordinated Universal Time (UTC) by a whole or half hour.
UTC replaced Greenwich Mean Time (GMT) as the world's primary time standard in 1972, though GMT remains in common use and is functionally equivalent to UTC for most purposes.
To convert between time zones, you simply add or subtract the difference in UTC offsets. EST is UTC-5; PST is UTC-8. The difference is 3 hours, so noon EST is 9 AM PST.
Daylight Saving Time Complications
Most US states and many countries shift their clocks forward one hour in spring and back in fall — Daylight Saving Time (DST). This changes the UTC offset temporarily:
- •EST (UTC-5) becomes EDT (UTC-4) in summer
- •PST (UTC-8) becomes PDT (UTC-7) in summer
- •Arizona (except Navajo Nation) does not observe DST
- •Most of the EU shifted to permanent summer time discussions but still observes DST
Our converter uses your browser's real-time knowledge of DST, so the live world clock grid is always accurate regardless of time of year.
US Time Zones at a Glance
The contiguous United States spans four primary time zones:
| Zone | Standard | DST | States |
|---|---|---|---|
| Eastern | UTC-5 (EST) | UTC-4 (EDT) | NY, FL, GA, OH... |
| Central | UTC-6 (CST) | UTC-5 (CDT) | TX, IL, MN... |
| Mountain | UTC-7 (MST) | UTC-6 (MDT) | CO, UT, NM... |
| Pacific | UTC-8 (PST) | UTC-7 (PDT) | CA, OR, WA |
Scheduling Across Time Zones
Remote work and global teams make cross-timezone scheduling a daily challenge. A few strategies that help:
- •Anchor to UTC: Always confirm meeting times in UTC to avoid DST confusion. "Let's meet at 15:00 UTC" is unambiguous.
- •Rotate meeting times: For recurring global calls, rotate the inconvenient early/late slot between regions rather than always burdening one team.
- •Know the overlap window: US East and Western Europe share 9 AM–12 PM EST / 3–6 PM CET. US West and Asia have almost no business-hour overlap.
- •Check for DST transitions: The US and EU change clocks on different dates, creating a two-week window each spring/fall when the usual offset changes.
International Date Line and Day Changes
The International Date Line (IDL) runs roughly along the 180-degree meridian in the Pacific Ocean. Crossing it moving east subtracts a day; moving west adds a day.
This is why a flight from Los Angeles to Tokyo — heading westward across the date line — can depart on a Tuesday and arrive Thursday, even though the flight is only about 11 hours.
Our converter shows a "next day" or "previous day" indicator whenever the converted time crosses midnight, so you always know which calendar date applies in the destination zone.
Half-Hour and 45-Minute Offset Zones
Most time zones are offset by whole hours from UTC, but several major regions use unusual offsets:
- •India (IST): UTC+5:30 — the world's largest democracy uses a half-hour offset to cover its full east-west span in a single zone.
- •Nepal (NPT): UTC+5:45 — one of only two zones with a 45-minute offset.
- •Australia (ACST): UTC+9:30 — central Australia uses a half-hour offset to separate Adelaide and Darwin from Sydney's UTC+10.
- •Iran (IRST): UTC+3:30 in winter, UTC+4:30 in summer (DST observed).