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Parse a decimal number with i18n format support (localized decimal points and thousands separators)


OK, let’s fix international numbers parsing and validation once and forever. I got the inspiration for this in a UI project because somehow the libraries we used didn’t do a great job, so I wrote my own parser, and this is a more polished version of it.

These are the design goals:

  • Simple. String in, float out, done. ✓
  • Accurate. Parses numbers and returns NaN for non-numbers. (=good for input validation) ✓
  • Lightweight. (<1k minified) ✓
  • Complete. No external dependencies ✓
  • Solid. 100% Code Coverage ✓
  • CLDR Support. Supports cldr data ✓

In it’s simplest form, you just use it as a parseFloat replacement.


Install with npm

npm i parse-decimal-number --save


parseDecimalNumber = require('parse-decimal-number');
// -> 12345678.90 
// -> 12345678.90 

parseDecimalNumber(string [,options])

Returns a float representation of string or NaN if string is not a parseable number. Use the optional options parameter to specify the thousands and decimal point characters.


string A String that is supposed to contain a number.

options optional A string, array or hash with thousands and decimal separators.

  • String a two-character string consisting of the thousands character followed by the decimal point character, e.g. ',.'

  • Array An array of two elements, the first being the thousands character, the second being the decimal point character, e.g. ['.',',']

  • Hash with the following elements (this is compatible with NumeralJS)

    • thousands thousands separator character. Default: ,
    • decimal decimal point character. Default: .

enforceGroupSize A boolean indicating whether to support that individual groups between the thousands character are exactly 3 digits


// -> 12345678.90 
String options
// -> 12345678.90 
Array options
// -> 12345678.90 
Hash options
var customSeparators = {thousands:'.',decimal:','};
// -> 12345678.90 


Returns a function that will take a string as an argument and return a float or NaN, just like parseDecimalNumber.


  const cldr = require('cldr');
  const locale = 'de_DE';
  const options = cldr.extractNumberSymbols(locale);
  const parse = parseDecimalNumber.withOptions(options);
  parse('123.456.789,0123'); // -> 123456789.0123 

Setting and Resetting Default Options


Set the default thousands and decimal characters that are used when no options are passed to parseDecimalNumber.

var defaultSeparators = {thousands:'.',decimal:','};
// -> 12345678.90 

has the same effect as parseDecimalNumber.setOptions({thousands:',',decimal:'.'};)

Using with cldr

You can easily apply CLDR data using the cldr package:

  const cldr = require('cldr');

Using with Numeral.js

Numeral.js is good at formatting numbers and comes with an extensive set of locale data that you can use with parse-decimal-number.

If you use numeral in your project, you can use their locale data as follows:

parseDecimalNumber('12.345.678,90', numeral.localeData('de').delimiters);
// -> 12345678.9 

You can of course use the same data to set the default values for parse-decimal-number:

// -> 12345678.9 

Done ☺️

Related Projects

To keep this project as small and modular as possible, the locale data itself has been left out of this library. If you need locale date, other projects might be helpful:

Running tests

{%= include("tests") %}


In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality, and please re-build the documentation with gulp-verb before submitting a pull request.


Andreas Pizsa (


Copyright (c) 2017 Andreas Pizsa (, contributors.