CSV to Excel
Turn a CSV into a real Excel .xlsx workbook in your browser. Leading zeros survive, the delimiter is detected automatically, and nothing is uploaded.
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All Document tools →This tool runs entirely in your browser. Nothing you enter is sent to our servers, so there is nothing for us to store or see.
About the CSV to Excel
Turn a CSV file into a real Excel workbook (.xlsx) rather than a CSV that Excel happens to open. The difference matters: a genuine workbook keeps its columns, opens the same way on every machine, and never shows the "some features may be lost" warning. The conversion runs entirely in this page on your own device, so the file is never uploaded.
The problem this solves is really Excel's import behaviour. Opening a CSV directly hands Excel the job of guessing what every column means, and it guesses badly in two specific ways that are hard to undo. Product codes and postcodes like 00714 lose their leading zeros and become numbers. Anything shaped vaguely like a date — 3-4, or a gene name such as MAR1 — is converted into one. Here, values are written as text unless you deliberately ask for numbers to be detected, and that detection only accepts values that survive the round trip unchanged.
The delimiter is detected for you, counting separators outside quoted fields so a single address reading "Paris, France" cannot outvote a genuinely semicolon-separated export. You can override it if the guess is wrong. Quoted fields, embedded commas, escaped quotes and values containing line breaks are all read to RFC 4180, and the byte-order mark Excel writes on its own exports is stripped so your first column is not named with an invisible character.
How to use the CSV to Excel
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Choose your CSV
Drop one or more .csv, .tsv or .txt files onto the box, or click to pick them. Each file becomes its own workbook.
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Check the delimiter
Leave it on automatic for almost every file. Set it by hand if your data is unusual enough to fool detection — a file that is mostly prose, for example.
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Decide about numbers and headers
Turn on number detection if you need to sum or chart the columns. Leave it off to keep every value exactly as written, which is the safe choice for codes and identifiers.
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Download the workbook
The .xlsx appears on the row with its row and column count. It is named after your CSV, and the sheet inside takes the same name.
Frequently asked questions
Is my file uploaded anywhere?
No. The CSV is read and the workbook is built entirely inside your browser, and nothing is sent to a server. You can disconnect from the internet once the page has loaded and the tool will keep working exactly as before.
Why not just open the CSV in Excel directly?
Because Excel then guesses what every column means, and two of its guesses are destructive. Leading zeros are stripped from codes and postcodes, and anything resembling a date is converted into one — including gene names and part numbers. A converted workbook has already decided those questions, so the file opens the same way for everyone who receives it.
Will my leading zeros and long numbers survive?
Yes. Every value is written as text unless you switch number detection on, and even then only values that survive a round trip unchanged are treated as numbers. So 00714 stays 00714, and a sixteen-digit card or account number is not rounded off into scientific notation.
How is the delimiter detected?
By counting each candidate separator outside quoted fields and taking the most frequent, so one address field containing "Paris, France" cannot outvote a genuinely semicolon-separated file. Commas, semicolons, tabs and pipes are all recognised, and you can override the result if it gets your file wrong.
Does it handle quoted fields and line breaks inside a cell?
Yes. Parsing follows RFC 4180, so quoted fields, embedded delimiters, escaped double quotes and values containing newlines all come through intact. A file with an unclosed quotation mark is reported rather than silently read as one enormous value.
Can I convert several CSVs at once?
Yes — queue up to twenty and each becomes its own workbook, processed one after another so a large batch cannot exhaust memory. Combining several CSVs into one multi-sheet workbook is a different job; use Merge CSV first if that is what you need.