# 시간대 변환 및 회의 일정 도구

> 한 시간대의 시각을 최대 12개 다른 시간대의 현지 시각으로 변환합니다. 일광 절약 시간을 반영하고 회의 일정 표를 제공합니다.

직접 계산할 수 있는 페이지: https://www.calcopenly.com/ko/datetime/time-zone-converter
분야: 날짜 및 시간 계산기

The converter reads the wall-clock time you enter in the source zone, subtracts that zone's UTC offset on that date to get a single instant, then adds each target zone's offset at the same instant. Offsets come from the IANA time zone database, so daylight-saving time is applied for the date you pick rather than for today.

The first worked example, 09:00 in New York on 15 January 2026, is 14:00 in London, 19:30 in India and 23:00 in Tokyo. The grid below the result shows all 24 hours of the source day in every zone, green where it falls inside Monday-to-Friday working hours (09:00 to 17:00 unless you change them), so a shared meeting slot is visible at a glance.

Some wall-clock times do not exist or happen twice. On 8 March 2026, 02:30 never occurs in New York and is read as 03:30; on 1 November 2026, 01:30 occurs twice and the first occurrence is used unless you choose the second.

## 입력

- **Date**
- **시간**
- **From time zone** (선택 항목: This device's time zone, UTC, Honolulu, Anchorage, Los Angeles, Denver, Phoenix, Chicago, Mexico City, New York, Toronto, Bogotá, Halifax, St John's, Santiago, São Paulo, Buenos Aires, Reykjavík, London, Dublin, Lisbon, Lagos, Casablanca, Paris, Berlin, Madrid, Rome, Amsterdam, Stockholm, Oslo, Johannesburg, Cairo, Athens, Helsinki, Kyiv, Istanbul, Nairobi, Moscow, Riyadh, Tehran, Dubai, Karachi, India (Kolkata), Kathmandu, Dhaka, Bangkok, Jakarta, Singapore, China (Shanghai), Hong Kong, Manila, Perth, Seoul, Tokyo, Adelaide, Brisbane, Sydney, Auckland, Chatham Islands, Kiritimati)
- **Convert to**: IANA names (Europe/Paris) or cities from the list, separated by commas.
- **If the time happens twice (clocks going back)** (선택 항목: Use the first occurrence, Use the second occurrence)
- **Working day starts**
- **Working day ends**

## 결과

- Converted time — 주요 결과
- UTC
- Offset of the source zone
- Daylight-saving check

## 공식

$$
t_{\text{UTC}} = t_{\text{local}} - \text{offset}_{\text{from}},\qquad t_{\text{target}} = t_{\text{UTC}} + \text{offset}_{\text{to}}(t_{\text{UTC}})
$$

## 계산 예제

### 9 am in New York in January

- Date: 2026-01-15
- 시간: 09:00
- From time zone: New York
- Convert to: Asia/Kolkata, Europe/London, Asia/Tokyo
- **Converted time: India (Kolkata) 19:30 · London 14:00 · Tokyo 23:00**
- **UTC: 2026-01-15T14:00:00Z**
- **Offset of the source zone: UTC−05:00**
- **Daylight-saving check: Exists once**
- 검증 출처: Python 3.8 dateutil.tz with system tzdata 2024a: datetime(2026,1,15,9,tzinfo=New_York).astimezone(...)

### A time skipped when New York springs forward

- Date: 2026-03-08
- 시간: 02:30
- From time zone: New York
- Convert to: Europe/London, Asia/Kolkata
- **Converted time: London 07:30 · India (Kolkata) 13:00**
- **UTC: 2026-03-08T07:30:00Z**
- **Daylight-saving check: Skipped by a DST change**
- 검증 출처: Python 3.8 dateutil.tz: datetime_exists(2026-03-08 02:30 New_York) is False; resolve_imaginary gives 03:30 EDT = 07:30Z

### A repeated hour when New York falls back, second occurrence

- Date: 2026-11-01
- 시간: 01:30
- From time zone: New York
- Convert to: Europe/London
- If the time happens twice (clocks going back): Use the second occurrence
- **Converted time: London 06:30**
- **UTC: 2026-11-01T06:30:00Z**
- **Offset of the source zone: UTC−05:00**
- **Daylight-saving check: Occurs twice (DST overlap)**
- 검증 출처: Python 3.8 dateutil.tz: datetime_ambiguous(2026-11-01 01:30 New_York) is True; fold=1 gives 01:30 EST = 06:30Z (fold=0 gives 05:30Z)

### Quarter-hour offsets

- Date: 2026-07-01
- 시간: 12:00
- From time zone: Kathmandu
- Convert to: Pacific/Chatham, America/St_Johns
- **Converted time: Chatham Islands 19:00 · St John's 03:45**
- **UTC: 2026-07-01T06:15:00Z**
- **Offset of the source zone: UTC+05:45**
- 검증 출처: Python 3.8 dateutil.tz: Kathmandu +05:45, Chatham +12:45 (NZ winter), St John's −02:30 (summer time)

## 자주 묻는 질문

### What is the difference between UTC and GMT?

On a clock they read the same, but UTC is an atomic time scale and GMT is a time zone. UTC is derived from International Atomic Time and kept within 0.9 seconds of the Earth's rotation by leap seconds; 27 have been added since 1972, the last on 31 December 2016. GMT is the UK's winter civil time; from late March to late October the UK uses BST, which is UTC+01:00.

### When do the clocks change for daylight saving time in 2026?

In the United States clocks go forward at 02:00 local time on the second Sunday in March and back on the first Sunday in November, the rule since 2007: 8 March and 1 November in 2026. The EU and UK change at 01:00 UTC on the last Sunday in March and October: 29 March and 25 October. Between 8 and 29 March, New York is 4 hours behind London instead of 5.

### Why use a zone name like America/New_York instead of EST?

An IANA name carries the zone's full history of offset and daylight-saving rules; an abbreviation is one fixed offset and is often ambiguous. EST means UTC−05:00, which is wrong for New York from March to November, when it is on EDT (UTC−04:00). IST can mean India (UTC+05:30), Irish or Israel Standard Time, and CST is both US Central and China Standard Time.

### Which time zones are offset by 30 or 45 minutes?

India uses UTC+05:30 all year, Iran UTC+03:30, Afghanistan UTC+04:30 and Myanmar UTC+06:30. Nepal is at UTC+05:45 and the Chatham Islands at UTC+12:45, or UTC+13:45 in the southern summer. Newfoundland is at UTC−03:30 in winter and South Australia at UTC+09:30 in winter, and both move by an hour for daylight saving.

### How many working hours do London and New York share?

Three hours for most of the year: 09:00 to 17:00 in New York is 14:00 to 22:00 in London, so the shared window is 14:00 to 17:00 London time. It widens to four hours in the weeks when only the US has changed its clocks, such as 8 to 29 March 2026. Tokyo's 09:00 to 17:00 does not overlap either city's working day.

### “시간대 변환 및 회의 일정 도구”의 정확도는 어느 정도인가요?

정확도는 입력값과 계산 방법의 가정에 따라 달라집니다. 십진 연산은 유효숫자 50자리를 사용하지만, 추정값·수치해석 방법·원본 데이터의 정밀도는 더 낮을 수 있습니다. 표시값을 반올림해도 이러한 한계는 사라지지 않습니다. 독립적인 출처의 풀이와 대조한 계산 예시: 4. 예를 들어 “9 am in New York in January”은 Python 3.8 dateutil.tz with system tzdata 2024a: datetime(2026,1,15,9,tzinfo=New_York).astimezone(...)와 대조해 확인합니다.

### 이 계산 방법의 출처는 무엇인가요?

IANA Time Zone Database; ECMA-402 Intl.DateTimeFormat (timeZone option); TC39 Temporal — time zones and resolving ambiguity.

## 출처

- [IANA Time Zone Database](https://www.iana.org/time-zones)
- [ECMA-402 Intl.DateTimeFormat (timeZone option)](https://tc39.es/ecma402/#datetimeformat-objects)
- [TC39 Temporal — time zones and resolving ambiguity](https://tc39.es/proposal-temporal/docs/timezone.html)