Acceptable Date and Timestamp Formats for CSV Files

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Formatting Dates and Timestamps for CSV Files

If you're going to be uploading a CSV of data into Klaviyo, these are the datetime formats Klaviyo will recognize. Note that all formats must include both a date as well as time component. If there's no time of day associated with your date, you can set it to be 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 2014-09-01 13:34:00

For example, the date September 1st, 2014 at 1:34:08 p.m. should be formatted using one of the following supported formats:

2014-09-01 13:34:08

2014-09-01 13:34:08+00:00

09/01/2014 13:34:08

09/01/14 13:34:08

09/01/2014 13:34

09/01/14 13:34


1409529600 (Unix)

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

How to Upload These Properties into Klaviyo

Below is an example of how you would upload your main list with custom properties "Date Added - Old ESP," "Last Open - Old ESP," and "Last Click - Old ESP" with one of the correct datetime formats.


When you import dates with timestamps, map this field to the date data type. However, when you import a date without a timestamp, a default time of midnight UTC will be applied to this date if it is mapped to the date data type. This may cause date based 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 instead.

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