datetime.timezone

Q: What is the difference between timezone and zoneinfo?

timezone is one fixed offset, forever. zoneinfo.ZoneInfo("America/New_York") is a named region whose offset changes with daylight saving and history, read from the IANA tz database. Both are tzinfo objects and plug into the same datetime methods.

Q: Why is timezone(timedelta(hours=-5)) printed with days=-1?

The offset is a timedelta, and a negative timedelta is normalized as -1 day plus a positive number of seconds: -5 hours = -1 day + 68400 seconds. str(tz) shows the friendly form, UTC-05:00.

The built-in tzinfo for fixed offsets. It knows nothing about daylight saving: +01:00 is +01:00 all year. For real regional zones (Europe/Paris) use the separate zoneinfo module.

datetime classPython 3.2+Live demo

Common call

timezone(timedelta(hours=-5))

Returns

datetime.timezone(datetime.timedelta(days=-1, seconds=68400))

Replaces

pytz.FixedOffset and hand-written tzinfo subclasses for offsets

Watch out

Fixed: no DST. Offsets must be strictly within ±24 h

timezone(offsetoffset — The UTC offset, strictly between -timedelta(hours=24) and timedelta(hours=24). Seconds and microseconds are allowed (3.7+).type: timedelta · required, namename — What tzname() and %Z return. Without it the name is generated: 'UTC+05:30', or 'UTC' for a zero offset.type: str · default: None=None)

→ timezone

Demo

Live evaluation

An offset in hours and minutes. repr() shows the normalized timedelta, str() the generated name.

Try:

Inputs

hoursinthours

minutesintminutes

Code

from datetime import timedelta, timezone
tz = timezone(timedelta(hours=5, minutes=30))
(tz, str(tz))

Result

(datetime.timezone(datetime.timedelta(seconds=19800)), 'UTC+05:30')

A zero offset with no name gives back the timezone.utc singleton, so its repr is datetime.timezone.utc. Converting keeps the instant: 23:00 UTC shown at -07:00 is 16:00 the same day, at +09:00 it would already be the next day. The name is a free-form label — timezone(timedelta(hours=3), "PST") is accepted and compares equal to any other +03:00.

Parameters

Name	Type	Required	Description
offset	timedelta	yes	The UTC offset, strictly between -timedelta(hours=24) and timedelta(hours=24). Seconds and microseconds are allowed (3.7+).
name	str	no (None)	What tzname() and %Z return. Without it the name is generated: 'UTC+05:30', or 'UTC' for a zero offset.

Return value

timezone — A tzinfo whose utcoffset() is always `offset` and whose dst() is always None.

Common patterns

Parse, then show in a fixed offset

Aware input converts directly with astimezone.

from datetime import datetime, timedelta, timezone
ist = timezone(timedelta(hours=5, minutes=30), 'IST')
local = datetime.fromisoformat('2026-09-29T12:00Z').astimezone(ist)

Real zones with DST

zoneinfo (Python 3.9+) gives a tzinfo that knows each region's rules.

from datetime import datetime
from zoneinfo import ZoneInfo
paris = datetime(2026, 7, 1, 12, tzinfo=ZoneInfo('Europe/Paris'))

Offset from an integer of minutes

e.g. a browser getTimezoneOffset() value (note its sign is inverted).

from datetime import timedelta, timezone
tz = timezone(timedelta(minutes=-js_offset_minutes))

Examples

1. A fixed offset

from datetime import timedelta, timezone timezone(timedelta(hours=5, minutes=30))

Returns

datetime.timezone(datetime.timedelta(seconds=19800))

2. Negative offsets use days=-1

from datetime import timedelta, timezone tz = timezone(timedelta(hours=-5)) (tz, str(tz))

Returns

(datetime.timezone(datetime.timedelta(days=-1, seconds=68400)), 'UTC-05:00')

3. A zero offset IS timezone.utc

from datetime import timedelta, timezone timezone(timedelta(0)) is timezone.utc

Returns

True

4. Convert with astimezone

from datetime import datetime, timedelta, timezone, UTC ist = timezone(timedelta(hours=5, minutes=30), 'IST') datetime(2026, 9, 29, 12, tzinfo=UTC).astimezone(ist)

Returns

datetime.datetime(2026, 9, 29, 17, 30, tzinfo=datetime.timezone(datetime.timedelta(seconds=19800), 'IST'))

5. The name feeds %Z

from datetime import datetime, timedelta, timezone ist = timezone(timedelta(hours=5, minutes=30), 'IST') datetime(2026, 9, 29, 12, tzinfo=ist).strftime('%H:%M %Z %z')

Returns

'12:00 IST +0530'

6. Equality ignores the name

from datetime import timedelta, timezone timezone(timedelta(hours=1)) == timezone(timedelta(hours=1), 'CET')

Returns

True

7. No DST — dst() is None

from datetime import timedelta, timezone timezone(timedelta(hours=2)).dst(None) is None

Returns

True

8. Cannot be subclassed

from datetime import timezone class MyZone(timezone): pass

Returns

TypeError: type 'datetime.timezone' is not an acceptable base type

Pitfalls

1. An int instead of a timedelta

The offset must be a timedelta, not hours as a number.

timezone(-5)

from datetime import timezone
timezone(-5)

TypeError: timezone() argument 1 must be datetime.timedelta, not int

timedelta(hours=-5)

from datetime import timedelta, timezone
timezone(timedelta(hours=-5))

datetime.timezone(datetime.timedelta(days=-1, seconds=68400))

2. Using a fixed offset for a region with DST

Paris is +01:00 in winter and +02:00 in summer. A timezone(timedelta(hours=1)) is wrong for half the year — the zoneinfo module knows the rules.

fixed +01:00 in July

from datetime import datetime, timedelta, timezone
datetime(2026, 7, 1, 12, tzinfo=timezone(timedelta(hours=1))).isoformat()

'2026-07-01T12:00:00+01:00'

the summer offset

from datetime import datetime, timedelta, timezone
datetime(2026, 7, 1, 12, tzinfo=timezone(timedelta(hours=2))).isoformat()

'2026-07-01T12:00:00+02:00'

3. Offsets of a day or more

Real offsets run from -12:00 to +14:00; the class allows anything strictly inside ±24 hours.

24 hours

from datetime import timedelta, timezone
timezone(timedelta(hours=24))

ValueError: offset must be a timedelta strictly between -timedelta(hours=24) and timedelta(hours=24), not datetime.timedelta(days=1).

within range

from datetime import timedelta, timezone
timezone(timedelta(hours=14))

datetime.timezone(datetime.timedelta(seconds=50400))

When to use

Use it

UTC (timezone.utc or its alias UTC) — the right tzinfo for stored timestamps
Offsets that really are fixed: parsed from ISO text, from an API, or a fixed business rule

Reach for something else

Regions with daylight saving time → zoneinfo.ZoneInfo("Europe/Paris")
Custom rules → subclass tzinfo (timezone itself cannot be subclassed)

Notes

CPython impl

PyDateTime_TimeZone in Modules/_datetimemodule.c; timezone(timedelta(0)) without a name returns the timezone.utc singleton

Range

timezone.min is -23:59 and timezone.max is +23:59; the constructor accepts anything strictly inside ±24 hours

Methods

utcoffset(dt) → offset, dst(dt) → None, tzname(dt) → name or generated UTC±HH:MM, fromutc(dt) → dt + offset

Equality

Two timezone objects are equal when their offsets are equal; the name is ignored

FAQ

How do I create a timezone with a UTC offset in Python? ▾

timezone(timedelta(hours=5, minutes=30)) for +05:30, timezone(timedelta(hours=-5)) for -05:00, and timezone.utc (or UTC on 3.11+) for zero. Pass it as tzinfo= when building a datetime, or to astimezone() to convert.

What is the difference between timezone and zoneinfo? ▾

Why is timezone(timedelta(hours=-5)) printed with days=-1? ▾

datetime.timezone

Demo

Parameters

Return value

Common patterns

Examples

Pitfalls

When to use

Notes

Related

FAQ