Convert CSV to Excel (XLSX)

How to convert CSV to Excel

1. Open a .csv, .tsv or .txt file, drop it on the tool, or paste rows. Check the table under Input; if everything is in one column or accents look wrong, set the delimiter or encoding under Import settings.
2. Set the Sheet name (it starts as the file name) and choose Value types.
3. Keep or change the header and layout options, then select Download XLSX and open the file in Excel, LibreOffice Calc or Google Sheets.

To convert many files with the same settings, choose Batch: convert several files. Each file becomes its own workbook and they download together as one ZIP. In a batch, each file must be 25 MB or smaller.

What each option does

Leading zeros, long numbers and formulas

Opening a CSV directly in Excel lets Excel guess each value: 00731 becomes 731, a 20-digit order number is rounded, and 1-2 may turn into a date. This converter writes the cells itself, so Excel doesn't guess.

• Leading zeros, ZIP codes, phone numbers and part numbers stay text in both modes. Number detection never converts a column that has a value with a leading zero.
• Excel keeps at most 15 significant digits of a number. Text mode keeps longer IDs exactly. With detection, a column whose whole numbers have up to 16 digits (up to 9,007,199,254,740,991) still becomes numbers, and Excel then changes digits after the 15th to zero, so keep card, account and other 16-digit ID columns as text.
• Cells that begin with =, +, - or @ are written as text, never as formulas, so nothing in the CSV is calculated or run when the workbook opens.
• Commas, quotes and line breaks inside quoted CSV values stay inside one cell. Leading and trailing spaces are kept.
• Empty CSV values become empty cells, not empty strings.
• Column names are used exactly as written. A blank header becomes Column 3, and a repeated one becomes name (2).

Troubleshooting

• A SUM in Excel returns 0. The column is text. Convert again with Detect numbers and true/false, or, if it still stays text, look for a value such as 1,5, $12 or n/a in that column with the CSV viewer.
• Everything is in column A. The delimiter was guessed wrong. Choose Comma, Semicolon, Tab or Pipe under Import settings.
• Accented letters look like é. The file is not UTF-8. Choose its encoding (often Windows-1252 for older Excel exports) under Import settings.
• A cell is longer than Excel allows. Excel cells hold at most 32,767 characters; the tool says how many cells are longer and creates no file. Shorten them in the CSV editor, or export to JSON instead.
• The file is too large for this tool. Excel conversion works on files up to 25 MB, 100,000 rows, 250 columns and 2 million cells. Split the CSV and convert the parts.

Limits and privacy

The CSV must open in the browser workspace: up to 25 MB, 100,000 rows, 250 columns and 2 million cells. That is well inside Excel's own sheet limit of 1,048,576 rows by 16,384 columns. Each conversion produces one workbook with one sheet.

The workbook is built in a background worker in this tab with the open-source write-excel-file library, so the page stays responsive and Cancel stops it. The CSV is never sent to a server. For a printable table instead, use CSV to PDF.

Example

An inventory file with leading-zero SKUs, a 20-digit barcode, a quoted comma and a formula-like value, converted with Detect numbers and true/false, sheet name inventory, and the cells read back from the downloaded file. qty and unit_price became numbers and in_stock became TRUE/FALSE. barcode stayed text because one value has 20 digits, and the =SUM value stayed text. With the default Keep every value as text, every cell is text, including 12 and 34.90.

sku,barcode,description,qty,unit_price,in_stock,formula_like
00731,4006381333931,"Desk lamp, brass",12,34.90,true,=SUM(A1:A2)
00732,12345678901234567890,Cable tidy,,4.50,false,+44 20 7946 0958

Sheet "inventory" — row 1 bold and frozen

Row 1: sku | barcode | description | qty | unit_price | in_stock | formula_like   (text)
Row 2: "00731" text | "4006381333931" text | "Desk lamp, brass" text | 12 number | 34.9 number | TRUE boolean | "=SUM(A1:A2)" text
Row 3: "00732" text | "12345678901234567890" text | "Cable tidy" text | (empty) | 4.5 number | FALSE boolean | "+44 20 7946 0958" text