DATETIME vs TIMESTAMP in BigQuery

UpdatedMarch 2, 2026

•1 min read

DATETIME vs TIMESTAMP in BigQuery

Constantin Lungu

Part of seriesPractical SQL

DATETIME and TIMESTAMP in BigQuery are not the same and should not be used interchangeably!

One thing I encounter from time to time is mixing of DATETIME and TIMESTAMP types. Even casually converting TIMESTAMP(DATETIME_COLUMN) with no timezone provided.

This should not be done and you will get a type mismatch error when you, for example, try to compare them, for a very good reason.

What's the difference?

➡ DATETIME is a local time, happening once per day across the globe, at different points in time - it's 17:00 on January 12 first in Tokyo, then Bangalore, London and finally Los Angeles.

➡ TIMESTAMP is an absolute point in time and uses the UTC as a reference.

You can of course convert between the two, but you will NEED to provide a timezone context:
- if starting with a DATETIME, you need to provide a source timezone for the TIMESTAMP to be computed
- if you have a TIMESTAMP, you need to provide a target timezone for the DATETIME to be computed.

See below an illustration of how it's done.

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