When adding an event or profile property to Klaviyo via the API or by uploading a CSV file, there are specific date and time formats that Klaviyo will recognize. Note that this does not apply to an event timestamp sent via the Track API, that timestamp must be unix time in seconds.
Acceptable Date and Timestamp Formats
See the example below for information around formatting your date and timestamps in a CSV file. Note that, you must format dates as either YYYY-MM-DD or MM/DD/YYYY. If there's no time of day associated with your date, you can set it to midnight by using the HH:MM:SS value 00:00:00.
If you do not include seconds on your timestamps they will default to 0. For example, a timestamp of
2014-09-01 13:34 would be submitted to Klaviyo as
For example, the date September 1st, 2014 at 1:34:08 p.m. should be formatted using one of the following supported formats:
If you need help reformatting your dates in a spreadsheet before converting it to a CSV file, head to our article, Format Dates for CSV Files.
Below is an example of what this CSV file may look like as you upload it with the correct date/time formats.
Note that, when you import dates with timestamps, this field maps to the date data type. However, when you import a date without a timestamp, a default time of midnight UTC is applied to this date when mapped to the date data type. This may cause date-property triggered flows to send a day early or late depending on the account’s timezone. For that reason, if you only have the date (no timestamp) to upload, then map it to the string data type.
For more information on uploading a CSV file to Klaviyo, head to our article on how to add subscribers to an existing list.