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Đổi múi giờ và lên lịch họp

Đổi giờ của một múi giờ sang giờ địa phương của tối đa 12 múi giờ khác, áp dụng giờ mùa hè và cung cấp bảng lên lịch họp.

Cập nhật Ví dụ đã kiểm tra: 4

= 2026-09-29
IANA names (Europe/Paris) or cities from the list, separated by commas.
Tùy chọn khác
Thử
Converted time
London 10:00 · New York 05:00 · India (Kolkata) 14:30 · Tokyo 18:00
Converted time: London 10:00 · New York 05:00 · India (Kolkata) 14:30 · Tokyo 18:00
UTC
2026-09-29T09:00:00Z
Offset of the source zone
UTC+00:00
Daylight-saving check
Exists once

09:00 on Tue 29 Sep 2026 in UTC is London 10:00 · New York 05:00 · India (Kolkata) 14:30 · Tokyo 18:00. Offsets come from the IANA database, so daylight-saving time on that date is already applied.

Working hours across zones (green = Mon–Fri working hours)

0120591221610232271134238124509135611014672111578312168941317910514181011615191112716201213817211314918221415101923151611200161712211171813222181914233192015042021161521221726222318372301948UTCLondonNew YorkIndia (Kolkata)Tokyo
Meeting planner for Tue 29 Sep 2026 (hours in UTC) Số hàng: 24
UTC (from)LondonNew YorkIndia (Kolkata)TokyoIn working hoursNote
00:0001:0020:00 (−1 day)05:3009:001 of 5
01:0002:0021:00 (−1 day)06:3010:001 of 5
02:0003:0022:00 (−1 day)07:3011:001 of 5
03:0004:0023:00 (−1 day)08:3012:001 of 5
04:0005:0000:0009:3013:002 of 5
05:0006:0001:0010:3014:002 of 5
06:0007:0002:0011:3015:002 of 5
07:0008:0003:0012:3016:002 of 5
08:0009:0004:0013:3017:002 of 5
09:0010:0005:0014:3018:003 of 5Selected hour
10:0011:0006:0015:3019:003 of 5
11:0012:0007:0016:3020:003 of 5
12:0013:0008:0017:3021:002 of 5
13:0014:0009:0018:3022:003 of 5
14:0015:0010:0019:3023:003 of 5
15:0016:0011:0020:3000:00 (+1 day)3 of 5
16:0017:0012:0021:3001:00 (+1 day)2 of 5
17:0018:0013:0022:3002:00 (+1 day)1 of 5
18:0019:0014:0023:3003:00 (+1 day)1 of 5
19:0020:0015:0000:30 (+1 day)04:00 (+1 day)1 of 5
20:0021:0016:0001:30 (+1 day)05:00 (+1 day)1 of 5
21:0022:0017:0002:30 (+1 day)06:00 (+1 day)0 of 5
22:0023:0018:0003:30 (+1 day)07:00 (+1 day)0 of 5
23:0000:00 (+1 day)19:0004:30 (+1 day)08:00 (+1 day)0 of 5
Cách tính S

  1. Source time as UTC

    09:00 on Tue 29 Sep 2026 in UTC is UTC+00:00, so the instant is 2026-09-29T09:00:00Z.

  2. London

    UTC+01:00 → 10:00 on Tue 29 Sep 2026.

  3. New York

    UTC−04:00 → 05:00 on Tue 29 Sep 2026.

  4. India (Kolkata)

    UTC+05:30 → 14:30 on Tue 29 Sep 2026.

  5. Tokyo

    UTC+09:00 → 18:00 on Tue 29 Sep 2026.

Giới thiệu Đổi múi giờ và lên lịch họp

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.

Ví dụ có lời giải

9 am in New York in January

Date
2026-01-15
Thời gian
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

Nguồn đối chiếu: 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
Thời gian
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

Nguồn đối chiếu: 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
Thời gian
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)

Nguồn đối chiếu: 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
Thời gian
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

Nguồn đối chiếu: Python 3.8 dateutil.tz: Kathmandu +05:45, Chatham +12:45 (NZ winter), St John's −02:30 (summer time)

Câu hỏi

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.

“Đổi múi giờ và lên lịch họp” chính xác đến mức nào?

Độ chính xác phụ thuộc vào dữ liệu nhập và giả định của phương pháp. Phép tính thập phân dùng 50 chữ số có nghĩa, nhưng ước lượng, phương pháp số và dữ liệu nguồn có thể kém chính xác hơn; làm tròn khi hiển thị không loại bỏ các giới hạn đó. Ví dụ có lời giải đã đối chiếu với nguồn độc lập: 4. Ví dụ, “9 am in New York in January” được kiểm tra bằng Python 3.8 dateutil.tz with system tzdata 2024a: datetime(2026,1,15,9,tzinfo=New_York).astimezone(...).

Phương pháp này lấy từ đâu?

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

Về công cụ tính này

tUTC=tlocal−offsetfrom,ttarget=tUTC+offsetto(tUTC)t_{\text{UTC}} = t_{\text{local}} - \text{offset}_{\text{from}},\qquad t_{\text{target}} = t_{\text{UTC}} + \text{offset}_{\text{to}}(t_{\text{UTC}})

Nguồn

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

Đã đối chiếu nguồn tham khảo

Công cụ tính này có 4 ví dụ đã giải với đáp án từ các nguồn độc lập. Chúng được chạy trong bộ kiểm thử và bạn cũng có thể chạy tại đây.

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