Free · formatted output · nothing uploads
CSV to Excel
A CSV opened in Excel is a wall of left-aligned text. Convert it here and it arrives formatted: typed columns, a totals row, a frozen header and a theme.
The file itself is never uploaded. Parsing, formatting and the .xlsx download all happen in this browser.
Converting is the easy half
Any tool can rename a .csv to .xlsx. The problem is what you get: every column is text, dates read as strings, currency keeps its dollar sign as a character rather than a format, and nothing sums. You still have an hour of cleanup ahead of you.
This converter does the second half too. It infers what each column actually holds, applies the matching Excel number format, converts the values so they behave as numbers and dates, and adds the structure a CSV cannot carry — a header row that stays frozen, sized columns, banding, and a totals row built from live SUM formulas.
Why CSV loses formatting in the first place
CSV is a plain-text format: rows separated by newlines, fields by commas. It has no concept of a cell type, a font, a column width or a formula. Everything a spreadsheet knows about presentation is discarded the moment it is exported to CSV — which is exactly why re-opening one always feels like starting over.
That also means the conversion has to make judgement calls: is 03/04/2026 March 4th or April 3rd? SuperSheet reads the whole column before deciding, and shows you the type it inferred so you can correct it in the chat if it guessed wrong.
Going the other way
You can also export back to CSV from the workspace if you want the cleaned values without the styling. For the formatting rules behind the output, see the number formatting guide, or start from a formatted template.
Frequently asked questions
- Will my dates convert correctly?
- SuperSheet reads the whole column before deciding on a type rather than guessing from the first row, then shows you the inferred type. Ambiguous formats like 03/04/2026 are genuinely ambiguous, so check the result — you can correct it in the chat.
- What about commas inside my data?
- Quoted fields are handled correctly, which is standard CSV behavior. A value with a comma inside quotes stays one field.
- Is there a row limit?
- SuperSheet works with the first 5,000 rows and files up to 15 MB. For bigger exports, convert in slices or trim to the columns that matter.
- Does the file get uploaded to convert it?
- No. The conversion happens entirely in your browser — there is no upload endpoint and nothing is stored. The optional AI reader does send the sheet's contents to the model provider for that one request; you can switch it off on the drop screen and the converter still works in full.