CSV to Excel Converter

About the CSV to Excel Converter

Opening a CSV file directly in Excel often damages it: 007 becomes 7, a 16-digit card or account number turns into 1.23457E+15 and loses its last digits, and 03/04/2026 may become the wrong date. This converter builds a real .xlsx instead, deciding each column’s type from all of its values: numbers, currency, percentages, dates and TRUE/FALSE become proper Excel values, while leading-zero codes, PIN codes, phone numbers and IDs longer than 15 digits stay text exactly as written.

Add one or more CSV or TSV files (each becomes a sheet) or paste the data. The delimiter and the encoding — UTF-8, UTF-16 or the Windows-1252 that older Excel writes — are detected, the header row is bold and frozen, column widths fit the data, and you can change the type of any column before downloading. Everything happens in your browser.

Common uses

• Turning bank, GST, payroll or e-commerce exports into a spreadsheet without corrupting account numbers and codes.
• Combining several CSV reports into one workbook with one sheet each.
• Opening semicolon-separated or UTF-16 files that Excel shows as one long column or garbled text.
• Preparing a CSV for colleagues who will filter, sort and sum it in Excel.

How column types are decided

A column is converted only when every value in it converts without losing anything; otherwise it stays text. Placeholders such as N/A, - or null may appear in a number or date column and stay as text cells.

• Text — leading zeros (007, 0484), more than 15 digits, a leading + on a phone number, or a header that names phone, mobile, PIN/ZIP/postal code, Aadhaar, account, IFSC, PAN, GSTIN, IBAN or similar codes.
• Number — 1499.5, 1,499.50, Indian grouping 1,25,000, accounting negatives (1,250.00), currency ₹1,499 / $, €, £, ¥, percentages 12.5% (stored as 0.125), exponents 1.5E3. The cell gets a matching number format; whole numbers of 12 to 15 digits (barcodes, order IDs) get the format 0, because Excel’s General format would show them as 1.23457E+11.
• Date or time — 2026-09-28, 28/09/2026, 09/28/2026, 28.09.2026, 28-Sep-2026, Sep 28, 2026, with optional times such as 14:30 or 2:30 PM. Two-digit years 00–29 mean 2000–2029 and 30–99 mean 1930–1999, as in Excel. Dates are stored as real Excel dates with a display format like the original.
• TRUE/FALSE — a column of true/false values.

Choosing Number for a column converts it even when the guess was Text: codes such as 007 then become the number 7. Values with more than 15 digits still stay text, because Excel cannot store them exactly.

Excel limits that are handled for you

Per Microsoft’s Excel specifications and limits: a sheet holds at most 1,048,576 rows and 16,384 columns, a cell at most 32,767 characters, and numbers keep 15 significant digits. Longer files continue on extra sheets named “name (2)”, “name (3)” with the header repeated; over-long cells are cut at 32,767 characters and listed; long digit strings stay text.

Reading the file correctly

Quoting follows RFC 4180: values may contain the delimiter, quotes (written twice) and line breaks when they are quoted. The delimiter (comma, semicolon, tab or pipe, or an Excel sep= line) is detected, and the encoding is read from a byte-order mark, recognised as UTF-16, checked as UTF-8 and otherwise read as Windows-1252. You can override both, and the decimal separator, when a file is unusual.

Limitations

• Files up to 100 MB each, and about 3 million cells in total; very large files take a few seconds to write.
• Formulas in the CSV (text starting with =) are written as text, never as formulas, so nothing runs when the workbook is opened.
• Only these date forms are recognised; anything else stays text — choose a date type for the column to try again with a fixed order.
• Time zones in timestamps (such as 2026-09-28T14:30:00Z) are not converted; such values stay text.

Privacy

Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.