Convert CSV to Excel Online
Convert CSV files to Excel format directly in your browser. No upload required — your data never leaves your device.
About converting CSV to Excel
Converting CSV to Excel is mostly about avoiding what Excel does when it opens a CSV directly. Double-click a CSV and Excel re-parses every cell with its own rules. It strips leading zeros from ZIP codes and product codes, shows long IDs in scientific notation, turns values like 3-4 or MARCH1 into dates, and may pick the wrong delimiter or encoding for your locale.
Here the CSV is parsed first and the .xlsx is written with typed cells, so Excel never gets to guess. Codes with leading zeros land as text cells. Numbers land as number cells, and true/false columns as Excel TRUE/FALSE values. The result is a single sheet named Sheet1 with the CSV header in row 1, ready for colleagues who want to sort and filter without an import wizard.
Two limits matter. Dates are written as text cells in ISO form (2026-03-02), not as Excel date serials, so date filters and date arithmetic need DATEVALUE() or a Text to Columns pass first. And Excel holds at most 1,048,576 rows per sheet, so filter or split larger CSVs before converting.
Not sure which format you need? Read the Excel vs CSV comparison.
Worked example
A small orders export with an ID, a customer name, a date, an amount (one missing) and a true/false flag, converted with the default settings.
Input (CSV)
order_id,customer,order_date,amount,shipped
1001,Acme Ltd,2026-03-02,249.5,true
1002,Brightside Co,2026-03-02,1200,false
1003,Acme Ltd,2026-03-05,89.99,true
1004,Northwind,2026-03-07,,falseOutput (Excel)
Excel workbook, first sheet (Sheet1)
| order_id | customer | order_date | amount | shipped |
|---|---|---|---|---|
| 1001 | Acme Ltd | 2026-03-02 | 249.5 | true |
| 1002 | Brightside Co | 2026-03-02 | 1200 | false |
| 1003 | Acme Ltd | 2026-03-05 | 89.99 | true |
| 1004 | Northwind | 2026-03-07 | NULL | false |
What changes when you convert CSV to Excel
- Row 1 holds the CSV header, and each CSV row becomes one worksheet row on Sheet1.
- order_id and amount are stored as numeric cells, so SUM and numeric sorting work straight away.
- shipped becomes Excel boolean cells showing TRUE and FALSE.
- order_date is a text cell containing 2026-03-02. It sorts correctly because ISO dates sort as text, but Excel does not treat it as a date.
- Order 1004's missing amount is an empty cell, which SUM and AVERAGE skip.
- No formatting, column widths, filters or formulas are added.
Your file is processed locally in your browser and is never uploaded. The free limit is 50 MB per file; larger files work if your device has the memory for them.
Frequently Asked Questions
Will leading zeros survive the conversion?
Yes, in columns that contain them. A column with a value such as 00123 is read as text and written to Excel as text cells, so the zeros stay. This is the main advantage over opening the CSV in Excel directly.
Why are my dates left-aligned in Excel?
They are text cells. The converter writes dates as ISO text rather than Excel serial numbers. Select the column and run Data > Text to Columns > Finish, or use =DATEVALUE(A2), to turn them into real dates.
What happens to 16-digit numbers such as account numbers?
Excel keeps only 15 significant digits for numbers, so a 16-digit value stored as a number loses its last digit when Excel opens the file. Integers above 9,007,199,254,740,991 are written as text and are safe. For identifiers rather than quantities, cast the column to text first with Cast Column Types.
What is Excel format?
Excel (XLSX) is Microsoft's spreadsheet format, widely used in business. It supports multiple sheets, formulas, and formatting.
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