# Dates and times

The Smartsheet API returns all dates and times in UTC and formatted for ISO-8601, YYYY-MM-DDTHH:MM:SSZ. If you specify a date and time, you should also send that information in ISO-8601 format. If a date/time needs to be displayed to an end-user in their local time zone, you must do the conversion using the user's time zone, which you can obtain by [getting the current user](/api/smartsheet/openapi/users/get-current-user).

You can optionally choose to receive and send dates/times in numeric format, as milliseconds since the UNIX epoch (midnight on January 1, 1970, in UTC), using the query string parameter numericDates with a value of true. This query parameter works for any API request.

> **Note:** Some SDK methods use language-specific Date objects, which require different date formats.