Time Zone Converter
Convert a time in one time zone to another. This tool uses fixed UTC offsets, so it does not account for daylight saving changes — always verify current offsets for your specific dates.
Formula
Time in zone B = Time in zone A + (Offset_B − Offset_A)
Where offsets are expressed as UTC±N.
Worked Examples
Example 1: 9 AM in New York (UTC−5) → London (UTC)
- Offset difference: 0 − (−5) = +5 hours.
- 9:00 + 5 = 14:00.
- Result: 9 AM EST = 2 PM GMT.
Example 2: 3 PM in London (UTC) → Tokyo (UTC+9)
- Offset difference: 9 − 0 = +9 hours.
- 15:00 + 9 = 24:00 → 00:00 next day.
- Result: 3 PM GMT = midnight in Tokyo the next day.
Example 3: 10 AM in Los Angeles (UTC−8) → Berlin (UTC+1)
- Offset difference: 1 − (−8) = +9 hours.
- 10:00 + 9 = 19:00.
- Result: 10 AM PST = 7 PM CET.
Reference Table: Major Cities
| City | Winter offset | Summer offset |
|---|---|---|
| Los Angeles | UTC−8 | UTC−7 |
| Denver | UTC−7 | UTC−6 |
| Chicago | UTC−6 | UTC−5 |
| New York | UTC−5 | UTC−4 |
| São Paulo | UTC−3 | UTC−3 (no DST) |
| London | UTC | UTC+1 |
| Paris / Berlin | UTC+1 | UTC+2 |
| Moscow | UTC+3 | UTC+3 (no DST) |
| Dubai | UTC+4 | UTC+4 (no DST) |
| Karachi | UTC+5 | UTC+5 (no DST) |
| Mumbai | UTC+5:30 | UTC+5:30 (no DST) |
| Bangkok | UTC+7 | UTC+7 (no DST) |
| Singapore | UTC+8 | UTC+8 (no DST) |
| Beijing | UTC+8 | UTC+8 (no DST) |
| Tokyo | UTC+9 | UTC+9 (no DST) |
| Sydney | UTC+10 | UTC+11 |
| Auckland | UTC+12 | UTC+13 |
Winter offsets apply when the northern hemisphere is in standard time (roughly November–March). Summer offsets apply during daylight saving time (roughly March–November). Southern hemisphere DST runs in opposite months.
Daylight Saving Time Notes
Many countries shift their clocks by one hour for daylight saving time (DST). This makes the "UTC offset" of a location depend on the date. Specific cases:
- United States: DST from the second Sunday of March to the first Sunday of November.
- European Union: DST from the last Sunday of March to the last Sunday of October.
- Australia: DST from the first Sunday of October to the first Sunday of April (southern hemisphere).
- No DST: China, Japan, India, most of Africa, and parts of South America and the Middle East.
Because DST transitions differ between regions, the offset difference between two cities can change twice a year for a period of a few weeks (spring and autumn "shoulder" periods).
Real-World Uses
- International scheduling: Coordinating meetings across continents.
- Travel planning: Estimating arrival times and jet lag.
- Remote work: Understanding when colleagues in other zones are available.
- Customer support: Providing service hours in the customer's local time.
- Broadcast and streaming: Scheduling live events for global audiences.
- Logistics and shipping: Coordinating pickup and delivery across zones.
Unit Definitions
UTC (Coordinated Universal Time)
The primary time standard by which the world regulates clocks and time. It is based on International Atomic Time with leap seconds to keep it close to mean solar time. UTC is not a time zone but a time standard; time zones are defined as offsets from UTC.
GMT (Greenwich Mean Time)
A time zone at UTC+0 based on the mean solar time at the Royal Observatory in Greenwich, London. In modern usage, GMT is often used interchangeably with UTC, though technically they are distinct (GMT is a time zone, UTC is a standard).
Related Converters
Frequently Asked Questions
How do you convert between time zones?
Add the offset difference between the two zones to the source time. If the source is in UTC−5 and the target is UTC+1, the difference is +6 hours, so add 6 hours to the source time.
What is the difference between UTC and GMT?
GMT is a time zone (UTC+0) based on mean solar time at Greenwich. UTC is a time standard maintained by atomic clocks and adjusted with leap seconds. In everyday use they are treated as equivalent.
Does this tool account for daylight saving time?
No. The tool uses fixed UTC offsets. Daylight saving time shifts clocks by an hour in many countries, so you must verify the current offset for your specific dates. This is not a live clock-based tool.
How many time zones are there?
Officially there are 24 standard time zones based on multiples of 15° longitude, each differing by one hour from adjacent zones. In practice there are more than 38 offsets in use because some countries use half-hour or quarter-hour offsets (India UTC+5:30, Nepal UTC+5:45).
What time zone is UTC?
UTC is not a time zone but a standard. It corresponds to the time zone at longitude 0° (Greenwich, London) during winter months. It is the reference from which all other time zones are defined.