> ## Documentation Index
> Fetch the complete documentation index at: https://help.maestra.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Customer Import Best Practices

Preparing your file before import helps you avoid errors and delays when loading customer data.

Your file should meet the following criteria:

* Up to 20 columns (inclusive).
* Fewer than 5% duplicate rows.

## Expected speed

If your import file meets the criteria above, you can estimate how long the job will take based on the total number of customers on your project.

| Number of customers | Expected speed          |
| ------------------- | ----------------------- |
| 50,001 — 99,999     | 150,000 rows per hour   |
| 100,000 — 999,999   | 300,000 rows per hour   |
| Over 1,000,000      | 1,000,000 rows per hour |

## If the import is slower than expected

When a file that meets the requirements is importing slowly, Maestra automatically detects the issue and starts investigating. If the speed stays low for an extended period, reach out to support chat.