Follow the guidelines in this topic to ensure that your file imports successfully.
You can import only one record type at a time. For ease of use, name the file the same name as the record type in Microsoft Dynamics CRM Online. For example, put all your contact records in a file named contacts.txt or contacts.csv.
You can easily create delimited .txt or .csv format files by using Microsoft Office Excel.
If your file uses only ASCII characters, save the file as a comma-delimited values (.csv) file.
Make sure the first line of the file contains column headings.
Make sure the first column heading is not the name of a record type.
Make sure data exists for all business-required attributes.
If records in your import file are related to an existing Microsoft Dynamics CRM Online record, make sure the column heading and data in the column that connects the records is valid, and prepare your file for automatic mapping.
Decide how to import drop-down list values in the file.
Note
By default, the maximum size of the file that you can upload is 4 megabytes (MB). This can be changed by your administrator. More information: Microsoft Knowledge Base Article 295626.