A module that finds the size and type of an image by fetching and reading as little data as needed.

fast, fastimage, image, size, dimensions, resolution, width, height, png, jpeg, bmp, gif, psd, tiff, webp, svg
npm install fastimage@4.1.0



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A module that finds the size and type of an image by fetching and reading as little data as needed.



Just run:

npm install fastimage


The signature is fastimage.info(source, [options], [callback]).

The source argument can be:

  • String representing a URL (only http and https protocol are supported).
  • String representing a local file path.
  • Buffer containing image data.
  • Stream containing image data.

The options object supports the following options:

  • threshold: The maximum about of data (in bytes) to downloaded or read before giving up. Default is 4096.
  • timeout: The maximum time (in milliseconds) to wait for a URL to be downloaded before giving up. Default is 30000 (30 s).
  • userAgent: The user agent to use when making HTTP(S) requests. Default is fastimage/$VERSION.

If callback is not provided, the method returns a Promise.


import { info } from 'fastimage'

info('http://fakeimg.pl/1000x1000/', (error, data) => {
  if (error) {
    // ...
  } else {
    // ...

const data = await info('http://fakeimg.pl/1000x1000/')

The callback argument (or the resolved value) will be an object with the following properties:

  "width": 1000, // The width of the image in pixels.
  "height": 1000, // The height of the image in pixels.
  "type": "png", // The type of the image. Can be one of the supported images formats (see section below).
  "time": 171.43721 // The time required for the operation, in milliseconds.
  "analyzed": 979, // The amount of data transferred (in bytes) or read (in case of files or Buffer) to identify the image.
  "realUrl": "https://fakeimg.pl/1000x1000/", // The final URL of the image after all the redirects. Only present if the source was a URL.
  "size": 17300, // The size of the image (in bytes). Only present if the source was a URL and  if the server returned the "Content-Length" HTTP header.


Calling fastimage.stream it will return a Writable stream which will emit the info event once informations are ready.

The stream accepts only the threshold option.

import { stream } from 'fastimage'

const pipe = createReadStream('/path/to/image.png').pipe(stream({ threshold: 100 }))

pipe.on('info', data => {
  // ...

Supported image formats

The supported image type are (thanks to the image-size module):

  • BMP
  • CUR
  • DDS
  • GIF
  • ICNS
  • ICO
  • JPEG
  • KTX
  • PNG
  • PSD
  • SVG
  • TIFF
  • WebP

ESM Only

This package only supports to be directly imported in a ESM context.

For informations on how to use it in a CommonJS context, please check this page.

Contributing to fastimage

  • Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
  • Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
  • Fork the project.
  • Start a feature/bugfix branch.
  • Commit and push until you are happy with your contribution.
  • Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.

Copyright (C) 2015 and above Shogun (shogun@cowtech.it).

Licensed under the MIT license, which can be found at https://choosealicense.com/licenses/isc.