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1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitchesChoose the parser based on both the input format and the Python type you need: use date.fromisoformat() for a supported ISO calendar date, datetime.fromisoformat() for a supported ISO timestamp, and strptime() when a known custom layout needs an explicit format string. Parsing does not determine what an ambiguous date means, so confirm the source convention before converting it.
Choose the right parser and result type
| Input | Desired result | Use | Key consideration |
|---|---|---|---|
Supported ISO date, such as 2024-07-15 |
date |
date.fromisoformat(value) |
Returns a calendar date; only documented ISO forms are accepted. |
Supported ISO timestamp, such as 2024-07-15T09:30:00+00:00 |
datetime |
datetime.fromisoformat(value) |
Can retain supported time and timezone information. |
| Known custom date layout | date |
date.strptime(value, format) |
The format must describe the input layout. |
| Known custom date-and-time layout | datetime |
datetime.strptime(value, format) |
Format-code behavior can vary by platform. |
These methods and their behavior are documented in the Python 3.14.7 datetime reference.
Parse an ISO date into a `date`
Use date.fromisoformat() when the value represents a calendar date without a time:
from datetime import date
value = "2024-07-15"
parsed_date = date.fromisoformat(value)
print(parsed_date) # 2024-07-15
print(type(parsed_date)) # <class 'datetime.date'>The method returns a date, which is appropriate for birthdays, due dates, or other values where a time of day is not part of the data. Documented inputs include the familiar YYYY-MM-DD form, compact YYYYMMDD, and ISO week dates.
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Do not assume this method accepts every string that could be described as ISO. The documented exclusions include reduced-precision dates such as YYYY-MM or YYYY, extended signed six-digit years, and ordinal dates such as YYYY-OOO. Use the exact format accepted by the method, or parse a different known layout explicitly.
Parse an ISO timestamp into a `datetime`
For a supported ISO date-time string, use datetime.fromisoformat(). The result carries date and time fields and can carry timezone information when the input includes a supported timezone designator:
from datetime import datetime
value = "2024-07-15T09:30:00+00:00"
parsed_datetime = datetime.fromisoformat(value)
print(parsed_datetime)
print(parsed_datetime.tzinfo)Supported examples include a trailing Z and numeric offsets such as +00:00. Preserve the distinction between a timestamp with timezone information and one without it: the parser does not infer a timezone for a string that omits one. The accepted forms have documented exceptions, so validate the specific input shape your source supplies.
Parse a known custom format with `strptime()`
For a non-ISO string, describe its layout with format directives. For example, %d is the day, %m the month, and %Y the four-digit year:
from datetime import datetime
value = "15/07/2024"
parsed_datetime = datetime.strptime(value, "%d/%m/%Y")
print(parsed_datetime) # 2024-07-15 00:00:00If the input contains only a date and you want a date, use date.strptime() where available:
from datetime import date
value = "15/07/2024"
parsed_date = date.strptime(value, "%d/%m/%Y")
print(parsed_date) # 2024-07-15A format mismatch raises ValueError. Catch it when invalid or unexpected input is a normal possibility:
from datetime import datetime
value = "31/02/2024"
try:
parsed = datetime.strptime(value, "%d/%m/%Y")
except ValueError as error:
print(f"Invalid date: {error}")Choose the format from the data contract, not merely from how one sample looks. For instance, 03/04/2024 could mean 3 April or March 4 depending on the source convention; a format string makes the convention explicit but cannot tell you which convention the source intended.
Handle partial dates and Python-version differences
Month and day without a year
A format that parses a day and month but omits the year relies on a default year that is not a leap year. As a result, a value such as February 29 cannot be safely parsed that way. If the source omits the year, supply an explicit year before parsing; the Python documentation illustrates using 1984, a leap year, for this purpose.
Python 3.13 added a deprecation warning for datetime.strptime() formats that specify a day without a year. The documentation says these forms may raise an error in Python 3.15. If the data has a year, include it in the format and input. If the year is genuinely absent, define how to supply or represent it rather than silently relying on a default.
`fromisoformat()` support
Python 3.11 broadened the accepted inputs for both date.fromisoformat() and datetime.fromisoformat(). In earlier releases, support was narrower: the date method was limited to YYYY-MM-DD, and the datetime method was limited to forms that could be emitted by isoformat(). If code must run on older Python versions, constrain inputs to forms supported by those versions or check the relevant version’s documentation.
Platform variation in format codes
strptime() relies on the platform C library for format-code support and behavior, so some codes can vary across platforms. When portability matters, favor widely supported directives and test the formats on the operating systems and Python versions where the code will run.
Quick Recap
Validate the result for the task
- Use
datewhen time-of-day information is irrelevant; usedatetimewhen it matters. - Use an ISO parser only for an input shape it documents as supported.
- For custom layouts, specify the source’s actual ordering and separators in the format string.
- Handle
ValueErrorfor malformed or impossible dates rather than assuming conversion always succeeds. - For timestamps, check whether timezone information is present and meaningful for subsequent comparisons or calculations.
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