CSV to Excel Converter

Drop the CSV in and download the .xlsx. It is a genuine Excel workbook, not a CSV with the extension changed, so it opens directly without an import step.

You can, but Excel guesses at column types while importing — which is how a postcode loses its leading zero and a product code becomes a date. Converting first puts the values in as text rather than leaving them to be interpreted.

Yes, along with quotes inside quotes and line breaks inside a field, which are the three things that break naive splitting on commas.

No. Both the parsing and the workbook are produced in your browser, which matters because spreadsheets are usually the most sensitive files anyone converts.

Because reading every field as text is the only way to guarantee that 007, 1-2 and 0044 survive intact — the moment something is free to guess, those become 7, a date and a number. The cost is that a column of figures is stored as digits rather than quantities, so SUM returns zero and sorting runs alphabetically, putting 100 before 20. Converting a genuine number column back is quick in Excel: select it, choose Data, then Text to Columns, and finish on General. Do it only to the columns that really are numbers, and leave codes and identifiers alone.

A CSV is a text file holding one table and nothing else — no styling, no formulas, no second sheet, no record of what is a date and what is a string. An .xlsx is a zipped set of XML files that carries all of that: cell types, number formats, column widths, several sheets, formulas that recalculate. So a CSV travels well, is readable by almost anything and diffs cleanly in version control, while an xlsx preserves the work you did to make the data legible. Choose by what opens the file next.

Much of Europe exports with semicolons, because the comma is already the decimal separator there — 1,5 means one and a half. Nothing inside the file records that choice, so a reader has to be told or has to guess, and a comma-only reader handed a semicolon file returns one wide column rather than an error, since each line is technically a single valid field. Sort it out before converting: re-export from the source with commas, or replace the semicolons in a text editor, taking care not to touch any that sit inside quoted fields.

That is an encoding mismatch — the file was written as UTF-8 and is being read as Windows-1252, or the other way round. A plain CSV records nothing about its own encoding, so whatever opens it falls back to a default that differs by application and by operating system. Export or save as UTF-8 where you have the choice. If Excel is the culprit, avoid double-clicking the file and use Data, then From Text/CSV, which shows a preview with an encoding selector so you can correct the guess before anything is imported.

A worksheet stops at 1,048,576 rows and 16,384 columns, a hard limit of the format rather than a setting you can raise. CSV has no such limit, so a multi-million-row export cannot become one sheet at all — it has to be split, or loaded with something built for the job, such as Power Query, a database, or a script. Anything running inside a browser tab is bounded by the memory your machine will hand that page, so data at that scale belongs with a command-line tool rather than a converter you paste into.