CSV to Excel.
Keep every ID.
Excel can save a CSV as XLSX. But if opening the CSV changes 00123 to 123, Save As keeps the changed value. Convert the original CSV here first, with every field stored as text.
Save As cannot bring lost digits back.
Double-clicking a CSV can make Excel interpret identifiers as numbers. This tool creates the XLSX directly from the original CSV, before Excel gets to interpret it.
Already using Excel’s Data → From Text/CSV and setting ID columns to Text? That works too. This page makes a text-typed workbook to hand over without asking the recipient to repeat those steps.
01 / INPUTYour original CSV.
Start with the original export,
before a spreadsheet changes your IDs.
UTF-8 CSV · up to 10 MB · one file at a time
IDs, dates, prices and quantities keep their original text. This version does not convert values for calculations.
Already missing digits? Check the original CSV. This tool preserves the values it contains; it cannot restore digits lost in an earlier export or save.
02 / OUTPUTReady for Excel.TEXT, INTACT
A workbook that keeps the small details.
Here’s what stays the same:
ILLUSTRATION ONLY / Choose a file or try the example.
Record counts, text rules and handover notes in the same workbook.
Before download, the workbook is read back and every data cell is checked against your CSV.
Small details. Big difference.
Keep the leading zeros.
00123SKUs, postal codes and account references stay as written, without adding or guessing digits.
Keep every digit.
123456789012345678Long identifiers are stored as text, so Excel does not need to turn them into rounded numbers.
Keep codes as codes.
1E10 · 03-04 · =1+1Scientific-notation-like, date-like and formula-like values stay literal text in the workbook.
Three steps. One checked workbook.
Choose the original export.
Use a UTF-8 CSV from the source system, before opening and resaving it in Excel. If the CSV itself has already lost digits, get a fresh export.
Check the preview.
Confirm the separator and whether the first row is a header. Every column is kept as text, including prices and quantities.
Create it. Hand it over.
Download the checked XLSX. The recipient can open it directly; the optional notes sheet explains how its values were preserved.
CSV to Excel questions, answered.
Can’t I open a CSV in Excel and save it as an XLSX?
Yes, if Excel imports the identifier columns as Text first. If Excel already turned 00123 into 123 when opening the CSV, Save As stores 123; it cannot recover the lost zero. This tool reads the original CSV as text and creates an XLSX with explicit text cells before Excel opens it.
Why does Excel remove leading zeros from CSV files?
CSV files do not carry spreadsheet cell types. When a spreadsheet interprets a field as a number, it may remove leading zeros or change long identifiers. This tool writes an XLSX with explicit text cells so the field text is preserved on opening.
Can I calculate with the prices and quantities?
All values are text in this version. Convert only the columns you need for arithmetic in Excel, after checking their decimal and thousands separators. Keep identifier columns as text.
What exactly does the check verify?
The generated workbook is read back in your browser. Every cell in the Data sheet is checked for the same text, text cell type and position as the parsed CSV; formula cells are not permitted. This checks the conversion, not whether the source data was already damaged.
What happens to blank lines, spaces and repeated headers?
Spaces, repeated header names, record order and line breaks inside quoted fields are preserved. Blank records stay as blank rows; one final line ending is treated as the end of the last record. The header setting changes the preview and counts, not the content of the Data sheet. No header is invented when the setting is off.
Which files are supported?
One UTF-8 CSV, with or without a UTF-8 BOM, up to 10 MB. Comma, semicolon, tab and pipe separators are supported. Limits are 50,000 data records plus an optional header, 256 columns, 250,000 total cells and 32,767 characters per cell. Files with invalid quoting, inconsistent field counts, unsupported control characters, ambiguous Excel escape-shaped text or a different encoding are rejected instead of silently changed.
Will identifiers stay intact if I save it as CSV again?
The downloaded XLSX stores text cell types. A CSV does not. Opening a later CSV export or converting these cells to numbers can change the values again. Hand over the XLSX and keep identifiers as text.
Your file stays with you.
All processing happens in this tab.
Your CSV is read, converted and checked on your device. This page does not upload file contents, call an AI service, or load analytics or advertising scripts.
Nothing saved by the tool.
No account, cookies, localStorage or IndexedDB copy is created by this page. Clear file discards its working data and generated download; leaving the page also clears the working state.
Your browser may keep history or downloads according to its settings. The hosting provider may log page and static-file requests. A downloaded workbook remains wherever you save it. Other UnjamKit pages have the site’s visit-statistics policy.