Python datetime.datetime.isoformat() Method: Usage and Examples

Export consistent machine-readable datetime text using isoformat().

How It Works

datetime.isoformat() creates an ISO-style string and includes a UTC offset for aware datetimes. The sep and timespec parameters control the separator and precision; they do not change the value.

Step-by-Step Example

from datetime import datetime, timezone
recorded_time = datetime(2026, 10, 17, 9, 5, 30, tzinfo=timezone.utc)
print(recorded_time.isoformat(timespec='seconds'))

Understanding the Example

The expression 'datetime(2026, 10, 17, 9, 5, 30, tzinfo=timezone.utc)' supplies the value stored as 'recorded_time'. This value is then used or checked by the later statements.
The print() call exposes the result so you can compare it with the behavior described above. Check the value and its type when experimenting.

A successful run of this example prints the following output:

2026-10-17T09:05:30+00:00

Where This Fits in a Real Program

In a real import pipeline, parsing is only the first stage. Convert each field to the intended type, reject missing or unexpected values and report which record failed. Keep the original source file unchanged until the normalized data has passed validation and an export has been checked.

Practice: Try It Yourself

Prefer ISO 8601 with explicit offsets for exchanging timestamps.

For this exercise, predict the result before running the changed code. Then explain the difference between the original and modified cases using the actual values, not just whether the program completed.

Common Beginner Mistakes

Assuming an ISO string without an offset is automatically UTC.
Serialize an aware datetime with second precision and parse it back.

Key Takeaways

Export consistent machine-readable datetime text using isoformat().
datetime.isoformat() creates an ISO-style string and includes a UTC offset for aware datetimes.
Apply the demonstrated operation to the practice input and verify its result before depending on it in a larger program.