When to Use Data Loader

Data Loader complements the web-based import wizards that are accessible from the Setup menu in the online application.

Required Editions
Available in: both Salesforce Classic (not available in all orgs) and Lightning Experience
Available in: Enterprise, Performance, Unlimited, and Developer editions

Refer to the following guidelines to determine which method best suits your business needs:

Use Data Loader When:

Data loader supports CSV files with a maximum 150,000,000 records. If you must load more than 150 million records, we recommend you work with a Salesforce partner or visit the AppExchange for a suitable partner product.
You must load into an object that isn’t yet supported by Data Import Wizard.
Your data includes complex field mappings that you must load consistently on a regular basis.
You want to schedule regular data loads, such as nightly imports.
You want to export your data for backup purposes.

You’re loading less than 50,000 records.
The object you must import is supported by import wizards. To see what objects they support, from Setup, enter Data Import Wizard in the Quick Find box, then select Import Wizard.
You want to prevent duplicates by uploading records according to account name and site, contact email address, or lead email address.
Your target object has fewer than 50 fields.
Your data doesn’t include complex field mappings.