Why does Excel show Ã© or â€™ instead of accents and apostrophes in a CSV?

The file is UTF-8 but has no byte-order mark, so Excel on Windows reads it in the legacy system code page and each multi-byte character turns into two or three wrong ones. Either import it with Data → From Text/CSV and pick 65001 (Unicode UTF-8) as the file origin, or re-save the file as 'CSV UTF-8' / with a UTF-8 BOM so a double-click opens it correctly.

Why does Excel put the whole CSV in one column?

Excel splits a double-clicked CSV on the list separator from your regional settings, not on whatever the file uses. In locales where the comma is the decimal separator — most of Europe and Latin America — that separator is a semicolon, so a comma-separated file lands in column A. Import with Data → From Text/CSV and choose Comma, add a first line reading sep=, or produce the file with semicolons.

How do I stop Excel removing leading zeros from a CSV?

Excel types every cell on open, and 02139 becomes the number 2139. Don't double-click: use Data → From Text/CSV → Transform Data and set the column to Text, or the legacy Text Import Wizard with column type Text. Nothing inside a plain CSV forces Excel to keep the zeros on a double-click.

Why do long IDs show as 1.23457E+15 and lose their last digits?

Excel stores numbers as 15 significant digits. A 16-digit card-style or order ID is converted to a number, displayed in scientific notation, and its trailing digits are replaced with zeros — permanently, once the file is saved. Import the column as Text instead of opening the file directly.

Why did Excel turn my values into dates?

Values like 3-4, 1/2 or MAR1 match Excel's date patterns and are converted on open. As with leading zeros, the only reliable fix is importing the column as Text.

The CSV opens wrong in Excel

The file is fine. Open it in a text editor and every character, comma and zero is where it should be. Excel is the one rewriting it — on the way in, before you see anything — and each symptom maps to one of its defaults.

What you see	What Excel did
`Ã©`, `Ã¼`, `â€™`, `ðŸ‘` instead of `é ü ' 👍`	Read UTF-8 as the Windows code page (no BOM)
Every field crammed into column A	Split on `;` because your locale's list separator is
`02139` became `2139`	Typed the ZIP code as a number
`4111111111111111` became `4.11111E+15`	Typed the ID as a number — 15-digit precision
`3-4` became `4-Mar`	Matched a date pattern

Google Sheets reads UTF-8 and detects the delimiter, so if the first two look fine there, the file itself is good. (Sheets guesses number types too, so the last three can show up there as well.)

Garbled characters: the missing BOM

A CSV has no header that says what encoding it is in. Excel on Windows guesses, and without a hint it guesses the legacy system code page (Windows-1252 in English locales). UTF-8 encodes é as two bytes, so it comes out as the two Windows-1252 characters Ã©.

The hint Excel looks for is a byte-order mark — the three bytes EF BB BF at the start of the file.

Opening someone else's file: Data → From Text/CSV, set File Origin to 65001: Unicode (UTF-8), Load.
Producing the file: write the BOM. In Excel that's Save As → CSV UTF-8 (Comma delimited). In Python, encoding="utf-8-sig". In pandas, df.to_csv(path, encoding="utf-8-sig"). In JavaScript, prepend "" to the string before you build the Blob.

Only add the BOM to files a person will open. Some scripts read it as part of the first header name (id instead of id).

Everything in one column: the list separator

A double-clicked CSV is split on the list separator from Windows regional settings, not on the character the file actually uses. Where the decimal separator is a comma — Germany, France, Spain, Italy, Brazil and most of Europe and Latin America — the list separator is a semicolon, so a comma-separated file never splits.

Three fixes, from least to most invasive:

Import instead of opening. Data → From Text/CSV, pick Comma as the delimiter.
Tell Excel in the file. Add sep=, as the very first line. Excel honours it and hides the line; other tools will treat it as data, so use it only for files meant for Excel.
Write semicolons. If the audience is all in one locale, produce the file with ; and the double-click just works.

Leading zeros, long IDs and surprise dates: type guessing

Excel converts every cell that looks like a number or a date the moment the file opens, and saving afterwards makes the damage permanent. ZIP codes lose their zeros, 16-digit IDs keep only 15 significant digits, and 3-4 becomes 4 March.

A plain CSV has no way to say "this column is text". The fix is on the opening side: Data → From Text/CSV → Transform Data, select the columns, Data Type → Text, then Close & Load. Teach whoever receives the file to do the same, or don't send them a CSV.

The ="02139" trick (writing each cell as a formula) does keep the zeros, but every other program then sees a formula instead of a value. It's a workaround for one viewer, not a fix.

Making the CSV in the first place

If the data started life as JSON — an API response, an export, an agent's output — the JSON to CSV converter writes the BOM by default, has a semicolon delimiter option for European Excel, flattens nested objects into columns, and can escape cells starting with =, +, - or @ so a spreadsheet doesn't run them as formulas. Going the other way, CSV to JSON keeps leading zeros and long IDs as strings.

Or don't send a file at all

Every symptom on this page is the recipient's spreadsheet reinterpreting your data. If the point is for someone to read the numbers, publish them as a table instead: paste the CSV into CSV to HTML table and share it. The link renders identically on every machine and every locale, leading zeros and all, and reviewers can select a cell and comment on it rather than replying "row 14 looks wrong". Commenting needs a free sign-in; reading doesn't.

Share a table that opens the same for everyone →