Convert CSV to Excel format
Supports CSVs up to 200,000 rows (including the header row) (files up to 250 MB). Conversion runs in the background — this tab stays responsive.
Click or drop a .csv file here
CSV to Excel builds an .xlsx workbook from a CSV file (or pasted CSV text) using the xlsx library entirely in your browser, then triggers a download — your data is never uploaded to a server. The file is read and parsed off the main thread in a Web Worker, so the page stays responsive even on large files.
Does it support file upload, or only pasted text?
Both — upload a .csv file, or paste CSV text directly into the box.
What output format does it produce?
Always .xlsx. There's no .xls (legacy Excel) option.
Is my data uploaded to a server?
No, the workbook is built entirely in your browser using the xlsx library, in a background Web Worker so the page never freezes.
Does it handle CSV values that contain commas, like quoted fields?
Yes — a value wrapped in double quotes (e.g. "Smith, John") is parsed as a single field and its comma is preserved intact, rather than being split into extra columns.
Why is there a row limit, if Excel itself allows over a million rows per sheet?
Excel's own format allows up to 1,048,576 rows per sheet, but converting a file anywhere near that size in a browser tab risks running out of memory and crashing the tab rather than just being slow. 200,000 rows is the limit we've measured to convert reliably on desktop; beyond that, split your CSV into smaller files first. The count includes the header row, the same way Excel itself counts it as row 1.
Why is the row limit lower on my phone?
On phones and tablets the cap is 20,000 rows instead of 200,000. Mobile browser tabs get killed at a much lower memory ceiling than desktop tabs, and large CSVs also produce large .xlsx downloads that are impractical to save on a phone — the lower cap keeps mobile conversions reliable.