Image Size & Resolution Checker

An image’s dimensions are the number of pixels across and down, written as width × height, for example 1920 × 1080. They decide how much detail the image holds and how large it can be shown before it looks blocky. Phone photos are often saved sideways with a note telling apps to turn them upright; the checker reports the size the way the image is shown. To change the dimensions, resize the image, for example to 1920 × 1080, or crop it to a new shape.

The aspect ratio is width compared with height, reduced to the simplest numbers. 1920 × 1080 is 16:9, 4032 × 3024 is 4:3 and 1080 × 1080 is 1:1. When the numbers don’t reduce neatly, as with many phone screenshots, the checker gives the closest common ratio. Two images with the same ratio can be resized into each other without stretching or cropping. To start from an empty canvas of an exact size and ratio instead, make a blank image in those dimensions.

File size, in KB or MB, is how much storage the image takes. It depends on the format and compression as much as on the dimensions, so two images of the same size in pixels can weigh very different amounts. To get under an upload limit, reduce the file size. The resolution shown in DPI is a number stored in the file for printing; many images have none, and it doesn’t change the pixels. To see how large an image prints, use the DPI checker.

Your device can show the same numbers. On an iPhone, open the photo in Photos and swipe up or tap the info button to see its dimensions and file size. In Google Photos on Android, swipe up on the photo. On Windows, right-click the file, choose Properties and open the Details tab. On a Mac, open the image in Preview and choose Tools, then Show Inspector. The checker above gives the same answer on any device, plus the aspect ratio, without hunting through menus.