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SSF Number Formatter

As explained in "Number Formats", modern spreadsheet file formats separate "content" from "presentation". Instead of storing a formatted value like $3.50, applications will store the underlying value (3.50) and the number format ($0.00). Parsers are expected to render values.

The SheetJS SSF ("SpreadSheet Format") library formats numbers according to the number formatting rules defined in Excel and other spreadsheet software1

A version of the library ships with the main file processing library. It is deeply integrated in SheetJS CE API functions including read2, write3, and sheet_to_json4.

The library is also available for standalone use on the SheetJS CDN5.

Source code and project documentation are hosted on the SheetJS git server at

Live Demo

The formatted text is calculated from the specified number format and value. Please report an issue if a particular format is not supported.

Live Editor

  1. The number formatting rules are sketched in ECMA-376. A rough grammar is defined in the MS-XLS specification.
  2. See read in "Reading Files"
  3. See write in "Writing Files"
  4. See sheet_to_json in "Utilities"
  5. See for more details.