CSV to Excel Converter

Examples

The first example is the Employee List preset. It is semicolon separated, one quoted cell holds a comma, and another quoted cell holds a line break, which is the shape that falls apart when a file is pasted straight into a grid.

ID;Name;Department;Location;Notes
1;Ada Lovelace;Research;"London, UK";Joined 2019
2;Grace Hopper;Engineering;Arlington;"Works nights
Mentors new staff"
3;Alan Turing;Research;Manchester;Quiet office

The second example is the Formula Safety preset, where a value begins with an equals sign and another begins with an at sign. Comma is the separator, the result is 4 rows and 3 columns, and the default options pack it into 2,220 bytes. Open that workbook and both suspicious cells read as plain text, so nothing runs on load.

When to use this tool

• An API hands back a CSV dump and the person who has to read it only opens Excel.
• Finance wants a prepared sheet with the header row already bold and the money columns stored as numbers rather than text.
• An admin tool from a European vendor exports semicolons, and the file opens as one long cell in a spreadsheet set to a comma locale.
• A quick look before an import, where the preview counts show right away whether the column total matches what the source claims.
• A sheet has to go out as an email attachment for a recipient who will not run a script or open a raw text file.
• Identifiers with leading zeros have to survive the trip into a spreadsheet, which means converting with number coercion switched off.
• A quoted file with commas and line breaks inside cells loses its shape when it is pasted straight into a grid.

Best practices

1. Keep the header option in step with the file. Leave it on when row one holds column names so the bold style lands there, and switch it off when the first line is a record of its own.
2. Read the preview counts before pressing Convert. A column count that jumps against what you expected means the separator setting is wrong for that particular file.
3. Leave formula escaping on for anything that arrived by email, from a web form, or from a ticket, since those are the usual sources of cells that begin with an equals sign.
4. Turn number coercion off when a column holds identifiers, phone numbers, zip codes, or any other value where a leading zero carries meaning.
5. Give the sheet a name you will recognize in the tab bar, because that name is also used for the file you download.
6. Split a large export into chunks before loading it, and close other heavy tabs so the browser has room for the parse and the zip at once.
7. Keep the original CSV next to the workbook so a later reader can repeat the conversion with different options and compare the two results.

Common mistakes

1. Letting auto-detect run on a file where separators mix. One comma inside a quoted field can outweigh the semicolon that really divides the columns, so pick the separator by hand for those files.
2. Treating the header option as cosmetic. With it off, the header row is counted as a record and shows up in the row total, and with it on for a file that has no header, the first record is styled bold and later readers treat it as a header.
3. Carrying formulas in from somewhere else. A cell that begins with an equals sign or an at sign can execute when the workbook opens, so keep escaping on for files you did not write.
4. Coercing numbers on identifiers. 00741 becomes 741 once the cell is numeric and the zeros never come back, so switch number coercion off for those columns.
5. Pushing a very large file at the tab. The parsed rows, the worksheet markup, and the zip all live in memory together, and a file at the top of the practical range can freeze the page while it compresses.
6. Expecting several sheets from one pass. This version writes a single worksheet per workbook, so a three-part source needs three conversions and three downloads.