CSV to Excel XLSX converter

CSV to XLSX runs through our table engine, creating one Excel sheet with a filterable header row, fitted column widths and no formulas.

Converted with Table engine · nothing stored
Free: 5 conversions a day · 5 MB each
Higher limits →

From real runs

What you get — and what changes

Element	Result	What happens
Rows and columns	Kept	Parsed CSV cells become worksheet cells in the same order after delimiter detection or your delimiter override.
Numeric strings	Changed	Numeric-looking strings become Excel numbers when type inference is on, which can strip ZIP-code leading zeros.
Dates	Changed	ISO dates and common US dates are recognized as date values where possible; ambiguous regional dates should be stored as text.
Sheet name	Changed	The sheetName option names the single output worksheet after Excel-invalid characters are cleaned.
Header presentation	Changed	The first row gets an AutoFilter and columns are widened to fit their longest value (capped at 60 characters); the header is not bolded or frozen, as the writer cannot style cells.
Formulas	Lost	No formulas are created from CSV text, even if a cell starts with an equals sign; generated workbooks contain values only.
CSV encoding markers	Changed	A UTF-8 BOM is used only for input decoding and is not retained as visible worksheet text.

Rows and columns Kept
Parsed CSV cells become worksheet cells in the same order after delimiter detection or your delimiter override.
Numeric strings Changed
Numeric-looking strings become Excel numbers when type inference is on, which can strip ZIP-code leading zeros.
Dates Changed
ISO dates and common US dates are recognized as date values where possible; ambiguous regional dates should be stored as text.
Sheet name Changed
The sheetName option names the single output worksheet after Excel-invalid characters are cleaned.
Header presentation Changed
The first row gets an AutoFilter and columns are widened to fit their longest value (capped at 60 characters); the header is not bolded or frozen, as the writer cannot style cells.
Formulas Lost
No formulas are created from CSV text, even if a cell starts with an equals sign; generated workbooks contain values only.
CSV encoding markers Changed
A UTF-8 BOM is used only for input decoding and is not retained as visible worksheet text.

Sample conversions

ZIP code safeguard

Input: CSV: customer,zip,total\nNina Patel,02134,"1,234.50"
Output: With type inference on, total becomes a number and zip may become 2134. With typeInference off, 02134 stays text for mailing lists.

US dates

Input: CSV: invoice,due\nINV-7,09/10/2026\nINV-8,2026-09-11
Output: XLSX date cells are created for recognized US and ISO dates; ambiguous dates should be pre-normalized.

Presentation defaults

Input: CSV with headers: sku,name,qty and 2,000 product rows.
Output: Workbook sheet named "Inventory" with filter arrows on sku,name,qty and columns sized to the longest value; the header scrolls with the data.

A real CSV → Excel XLSX run

We converted our CSV sample (226 B) with Table engine on 2026-10-20. It took 6 ms and produced a 17 KB Excel XLSX file, 76× larger than the input. The engine raised no warnings.

Input · sample.csv · 226 B

4 data rows × 5 columns; header: company,stage,arr,owner,close_date

Rows: 4
Columns: 5
Header: company,stage,arr,owner,close_date

Output · sample.xlsx · 17 KB

Workbook with 1 sheet (Sheet1); first sheet 5 rows, 25 cells, 0 formulas, header filter, fitted column widths

Sheets: 1
Sheet names: Sheet1
Rows: 5
Cells: 25
Formulas: 0
Header filter: yes
Column widths: fitted

Options and when to change them

typeInference: Turn off for ZIP codes, order IDs, SKUs, and any numeric-looking identifier that must remain text.
sheetName: Set a descriptive sheet name such as Orders or Inventory instead of the default Sheet1.
delimiter: Override auto-detection for semicolon, tab, or pipe source files if the preview shows shifted columns.
dateHandling: Use date recognition for Excel sorting and formulas, or keep text when regional date ambiguity matters.

Do it yourself

pandas

bash

python - <<'PY'
import pandas as pd
with pd.ExcelWriter("out.xlsx", engine="openpyxl") as writer:
    pd.read_csv("in.csv", dtype={"zip": "string"}).to_excel(writer, index=False, sheet_name="Orders")
PY

Add bold headers or freeze panes with openpyxl after writing; our output sets a filter and column widths only.

csvkit plus in2csv

bash

in2csv in.csv > normalized.csv

csvkit is useful for normalizing CSV, but creating styled XLSX requires Python or spreadsheet tooling.

CSV to Excel XLSX by API or MCP

The HTTP API and the MCP server run the exact engine this page uses (Table engine); the response carries the same warnings the web converter shows. Check support first with GET /api/v1/pairs?from=csv&to=xlsx.

curl

curl -X POST https://filetypeconverters.com/api/v1/convert \
  -H "Authorization: Bearer $FTC_API_KEY" \
  -F "file=@input.csv" -F "from=csv" -F "to=xlsx" \
  -F 'options={"delimiter":","}' \
  --output output.xlsx

Options this engine accepts for CSV → Excel XLSX

Key	Applies to	Type	Default
delimiter	Reading CSV	string	,
header	Reading CSV	boolean	true
quote	Reading CSV	string	"
encoding	Reading CSV	utf-8 · latin1	utf-8
sheetName	Writing Excel XLSX	string

API reference

When this is the wrong conversion

If you need formulas created from business rules, build the workbook in Excel or a spreadsheet library after conversion.
If the source has more rows than Excel supports, keep CSV or use Parquet instead.
For strict machine ingestion, XLSX can introduce Excel-specific typing; CSV or Parquet may be safer.

CSV to Excel XLSX questions

Will ZIP codes keep leading zeros in CSV to XLSX?

Only when they are treated as text. Turn typeInference off for ZIP codes such as 02134 so Excel does not display 2134.

Does the converter create Excel formulas?

No. The XLSX contains values only. Text beginning with equals is not converted into a live formula.

Can I name the output worksheet?

Yes. Use sheetName to set one worksheet name. The browser converter creates a single-sheet workbook.