Guide

How to Find Duplicate Rows and Bad Columns in CSV Files

Detect duplicate rows, inconsistent column types, missing values, bad headers, and suspicious CSV data before import or analysis.

Quick Answer

Duplicate rows and bad columns can quietly damage reports, imports, customer lists, and product feeds. A quick profile pass helps catch the problems before the CSV moves downstream.

Step-by-Step

  1. Profile the CSV to understand row count, columns, blank values, and likely data types.
  2. Check for duplicate rows or repeated keys such as email, SKU, order ID, or product ID.
  3. Look for columns with mixed data types, strange date formats, or unexpected empty values.
  4. Normalize field names so later mapping and formulas are easier.
  5. Create a cleaned sample and compare it against the original before import.

Recommended Workflow

Open the most relevant calculator or utility first, enter a realistic starting point, then use the supporting tools to check assumptions, clean inputs, or prepare the final output.

FAQs

What counts as a duplicate row?

It depends on the job. Sometimes the entire row must match; other times a key field like email or SKU should be unique.

What is a bad column?

A bad column may have inconsistent types, missing required values, unclear headers, mixed formats, or values that do not match the destination system.

Should I delete duplicates automatically?

Not before reviewing them. Some repeated rows may represent legitimate separate transactions.