IrfanView is a famous photo viewer and editor software. It supports a wide range of formats including JPG, PNG, BMP, GIF, TIF, CUR, etc. You can utilize it for many purposes, like CDR viewer, batch file renamer, RAW to JPEG converter, etc. This software can also be used to view image metadata along with image DPI.
To use it as a DPI checker, open an image and go to Image menu > Information option. Or, you can simply press key ‘I‘ to view image properties. In Image Properties, you can view information of picture including its original size, original colors, disk size, memory size, print size, compression, etc. There, you can also see the resolution of the image in DPI, as highlighted in the above screenshot. If you wish, you can also change DPI of the image as per your requirement.
For more information related to an image, click on EXIF info button. A new dialog box with EXIF tag information will open up. You can view image creation date and time, camera model, image width and length, Exifoffset, ExifVersion, flash, ISO speed ratings, exposure mode, SensingMethod, GPS information, etc. It also lets you copy these information to clipboard. In addition, you can also edit IPTC information.