CSV to Excel, With Nothing Guessed
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- 100% Free
- Zero Server Data
Opening a CSV in Excel or Google Sheets means letting it guess what every column holds, and the guesses that go wrong go wrong permanently. A phone number loses its leading zero. A thirteen-digit ID becomes 1.23457E+12. A product code of 00123 becomes 123, and a ratio written 3/4 becomes the fourth of March. This reads your file, tells you exactly how many values in which columns are at risk, and writes a real .xlsx where every column says what it is. Nothing is guessed, because nothing has to be.
1 · The CSV
2 · What each column holds
Text keeps every character exactly as it is. Choose Number only where the column really is a quantity you want to add up.
Frequently asked questions
Google Sheets already opens a CSV. Why use this?
Because opening it is not the problem. Sheets and Excel both decide, value by value, what each one is, and a phone number written 081-234-5678 is a number to them, so the zero goes. So does the one in front of a product code, and a thirteen-digit ID becomes 1.23457E+12, and 3/4 becomes a date. Once you save, that is what the file says. This writes a spreadsheet where each column states its type, so there is nothing left to guess at.
What does choosing Text actually do?
It writes the cell as text in the file itself, not as a number that happens to look right. The distinction matters later: a colleague who sorts, filters or re-saves your spreadsheet will not find the zeros gone afterwards. Columns are suggested as Number only when every value in them is a plain number that nothing would change.
Is my file uploaded?
No. Your browser reads the CSV, works out its encoding, and writes the .xlsx, all in the tab. The site’s security policy sets connect-src ‘none’, so the browser blocks network requests from these pages, so nothing could be sent even if the code tried. The files people convert are customer lists and payroll exports, which are exactly the files that should not be handed to a website.
What about Thai text and other alphabets?
They arrive intact, and this is the other half of the problem with CSV. A .xlsx states its encoding inside the file, so there is no byte-order mark to remember and no chance of the alphabet being guessed wrong. If you need to stay with CSV, the tool for fixing that is on this site as well.
A cell in my file starts with an equals sign. What happens to it?
It stays a value. A cell beginning with =, + or @ is treated as a formula by every spreadsheet, which is how a downloaded file can run something on the machine that opens it. Written as text, it is what it always was.
Does it handle several sheets, or formulas, or formatting?
No. It writes one sheet of values with the types stated, and nothing else: no formulas, no colours, no charts. That is the whole job, and a converter that tried to do more would be a worse converter.