Changing the type or size of multiple image files at once

Updated: 12/31/2017 by Computer Hope

When working with image files you may want to change the size, format, or other settings. Whether it's to modify them to work with a website, fit onto a CD, or mail them to your friends or family, the process can be time-consuming. It is even worse when working with dozens or even hundreds of different files as they would normally all have to opened and changed manually.

Thankfully there are free image programs, such as IrfanView, that allow you to run a batch conversion to change almost any setting of the images into another setting in a few seconds. Below are steps on how you can use IrfanView to change the type, size, or other settings of multiple image files all at once.

  1. Download and install IrfanView onto your computer. You can find a download for this program at:
  2. Open the program once installed on your computer.
  3. In IrfanView, click File and select Batch Conversion/Rename.
  4. In the Batch conversion window, browse to the location of your image files, select each of the images you want to convert, and then click the Add button to add the files to the input files.
  5. If you do not want the new image files to be placed in the C:\TEMP directory, specify a new output directory.

Irfan view batch multiple image convert

Change format

Once the files have been added, if you're changing the image files to a different format, change the output format to any of the options shown below.

Supported formats: BMP, ECW, EMF, GIF, ICO, JP2, JPG, JPM, LDF, LWF, PCX, PBM, PGM, PNG, PPM, RAW, TGA, or TIF.

Change size

If you need to change the size of each of the files to a new size, click the 'Set advanced options' button, check the RESIZE box, and specify the new width and height. If you want to reduce the percentage size of the image, select the 'Set new size as percentage of original' option instead.


We always suggest also checking the Use Resample function (better quality) box also when resizing images as it can greatly improve the quality.

Change the name of all the files

If you need to change the name format of multiple files select the Batch rename or Batch conversion - Rename result files option and enter a name pattern.

Once you have specified all the changes you want to make during the batch conversion, click Start in the Batch conversion window.

Start the process


Click the Options button next to the Output Format section, and make sure the image quality is set to the maximum to help prevent any decrease in image quality.

When you've adjusted all the settings the way you want them, click Start to begin processing.