How to clean up a messy spreadsheet

Invisible trailing spaces are why your lookup fails and your totals are wrong. Cleaning first is worth the two minutes.

Data collected by people is messy in predictable ways. Cleaning it before analysis prevents a category of bug that is genuinely hard to spot afterwards.

Step-by-step

1. Add your file.
2. Choose what to clean.
3. Review the summary of what changed.
4. Download.

The problems worth fixing

Trailing and leading spaces. The big one. "London " and "London" are different values to every piece of software, and identical to every human. This produces duplicate categories, failed lookups and totals that are quietly short.

Blank rows and columns. Break sorting and range detection, and cause charts to include empty categories.

Duplicate rows. Usually from merging exports or a double submission. They inflate every total.

Inconsistent case. "YES", "Yes" and "yes" grouping as three categories.

Review before you accept

Deduplication is the one to check. Two rows can be genuinely identical and both real — two customers with the same name buying the same item on the same day is unusual, not impossible. Read the summary rather than trusting it blindly.

Frequently asked questions

Why do my lookups fail on values that look identical?

Almost always a trailing space in one of them. It is invisible on screen and makes the two values different to any software.

Is deduplication safe?

Check the summary. Identical rows are sometimes genuinely distinct records, so review what was removed rather than accepting it automatically.

Is my spreadsheet uploaded?

No. It is processed entirely in your browser.