Format Guidelines for Your Import File

When you import contacts to Mailchimp, you’ll match each column in your import file to a field in your Mailchimp list. Certain types of list fields, like email address and birthday, require a specific format to import correctly.

In this article, you'll learn how to format each column in your file to get the best results when you import.

Before You Start

  • If you've already started an import, learn how to review and edit your list fields or troubleshoot your import.
  • The only field Mailchimp requires is Email Address. Other fields are optional, but may be necessary for personalization, segmentation, or other features.
  • Clearly label each column in your import file so you can easily choose the field type during the import process. For example, if you have a column named "Contact Email Addresses," you'll know to choose the Email Address field type.
  • You can arrange the columns in your file in any order.

Email Address

You must include an email address column in your import file, and only one email for each contact. Review this column for anything that might cause syntax errors, like missing information, unsupported characters, and extra spaces before or after an address. For example, we can only support international characters like ñ or é if they come after the @ symbol.


Text fields are limited to a maximum of 255 bytes of information, and will be clipped if the limit is exceeded. In many alphabets, this is equal to 255 characters. Some alphabets or symbolic characters, like emoji, use more than one byte of information per character, so it isn't always a one-to-one ratio.

Use text fields for:

  • first name and last name
  • language preferences
  • numbers without comma separators
  • additional data you want to add to your list, like job title or company name


The address field is designed to contain each contact’s complete mailing address, which can be used with postcards, segmentation, and other features. This field is automatically included when you create a list, but is hidden from signup forms unless you choose to make it visible.

Here are some things to check before you import data to an address field.

  • Include each contact’s complete address, including the zip code and country. If the address information in your file is stored in multiple columns, combine them during the import.
  • Separate each part of the address with two spaces instead of commas.
  • Each line of the address must be fewer than 45 characters.
  • Use the two-letter country code instead of the country name. Our system will attempt to recognize countries by name, but it increases the likelihood of error.
  • A United Kingdom address with UK as the country will not import correctly. You’ll need to use GB instead.


The phone field is included when you create a new list, but is hidden from signup forms unless you choose to make it visible. It uses international format by default. If you know you’ll only have U.S. phone numbers, choose the (###) ###-#### format.

Zip Code

Use the zip code field in combination with text fields if you have U.S. address data stored in separate columns and don’t want to combine them. To store international postal codes, use an additional text field. Zip code fields are limited to five digits.


Certain features, like postcards and address-based segmentation, won’t work with address data stored in separate list fields. If the address information in your file is stored in multiple columns, we'll help you combine them when you import.


Use a number field to import numbers or currency values to your list. We'll add comma separators to large numbers like 1,000 or 1,000,000.



To import dates other than birthdays, use either the ISO Standard year-month-date format (YYYY-MM-DD) or month-day-year format (MM-DD-YYYY).

Mailchimp will attempt to convert the date field to match your account's default date format. For best results, we recommend that you use the ISO Standard format, YYYY-MM-DD.


If you store your contacts' birthdays in your list, you can use this information to send annual birthday automations that include special offers or just friendly messages. You'll need to import this information into a birthday field instead of a regular date field. Be sure to use the ISO Standard year-month-date format (YYYY-MM-DD).

Screen Shot 2019-02-07 at 1.06.47 PM


Image fields must contain the full source URL for a hosted image, which can be used to insert personalized images in campaigns.


Website fields can be used to store custom links for each contact and must include the full URL.

Marketing Permissions

If you add contacts who have given GDPR-friendly consent for marketing permissions, you can import that information to Mailchimp. To match the column to a Mailchimp list field, select Marketing Permissions for the column name. Imported permissions must match the marketing permission options you specified for this list in your GDPR-friendly form.


If you plan to use groups in your list, you can add subscribers to groups during the import process.

In your file, label the group column to match your group category. For each contact, include their group names. To add a contact to more than one group name, separate each name with a comma and a space.

For example, if you have a Newsletter Preferences group category and the group names are Student Events, News, and Donations, format the Newsletter Preferences cell for someone in all three groups like this.

image shows Newsletter Preferences column cell that contains Students, Events, News, Donations

Download a Sample Import File

If you need help, try our sample import file as a starting point. The sample file contains columns for a basic import that includes subscriber email address, first name, and last name. Each column in the file corresponds to a field in your Mailchimp list.

Download the sample CSV file, and replace the sample data with your subscriber data. You can also add more columns to the file, like phone numbers or groups. Follow the format guidelines for different types of information, to update your Mailchimp list correctly.

Sample File

Click the link to download the sample CSV import file. For best results, open the file in a spreadsheet program like Microsoft Excel or Google Sheets.

Sample CSV Import File

After you update the file with your subscriber information and save it, learn how to import it into Mailchimp.


The data contained in the sample import file is not actual contact data and has been created for informational purposes only. Replace the sample information before you import.

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