Want to know how to resize an image in GIMP? Good news – you’re in the right place! In this GIMP tutorial, I’ll show you how to scale, or resize, your images easily and properly using this awesome free photo editor!
1.Open the Image You Want to Use in GIMP
Regardless of whether you are on a PC, Linuc, or MAC computer, just open up your GIMP program (I recommend using the latest version, which you can always download for free from GIMP.org) and go to File>Open (denoted by the red arrow in the image above).
This will bring up the “Open Image” dialogue, allowing you to search for the image file on your computer. In my case, I am going to navigate to my Downloads folder on my C: drive (where I have my photo currently stored). I can do this via the “Places” section, as denoted by the blue arrow in the image above. Once I am in my Downloads folder (as you can see via the red arrow), I can scroll down until I find the image file I want to open. Clicking on the image file will generate a preview on the right side of the Open Image dialogue window under “Preview” (if the preview does not generate automatically, click the area that says “Click to Preview” – denoted by the green arrow). You can either double click on the file name, or simply click the “Open” button to open the image file into GIMP.
2.Open Up the Scale Image Feature
Once your image file is open in GIMP, you will see the current file size of your photo in the very top portion of the GIMP window (denoted by the red arrow in the photo above).
Right now, my photo is 5,889 pixels by 3,926 pixels.To scale the resize the photo so that it is larger or smaller, I simply need to go to Image>Scale Image.
This will bring up the Scale Image dialogue (shown above). Under the first section titled “Image Size” you will see the total Width and Height of your image. To the right of these values are arrows that allow you to manually adjust the image size up or down, as well as a chain-link icon (red arrow) that allows you to lock or unlock the aspect ratio of the image (in other words, any change to one dimension – i.e. Width – will automatically adjust the other dimension – i.e. Height – so that the image doesn’t appear smushed or stretched out).
To the right of the chain link icon are the units that your image’s measurements are being displayed in (green arrow) – in this case it is pixels (px). You can click on this unit dropdown to change the unit to any of the available units available within GIMP (I’ll stick with units for this tutorial).
3.Set the Dimensions You Want to Scale Your Image To
You can manually type in the values you want to set for your Width in the box next to it. I typed in “1920” for the width. Next, press the tab key to have the height value update automatically (assuming your chain-link icon is locked), or you can unlink your values and manually type in a value for the height. My height automatically updated to 1280 px since I kept my chain-link icon locked.
4.Set Your Resolution
Below the image dimensions is the X and Y resolution. I recommend always keeping these two values the same. The resolution is going to determine the overall quality of the image – setting a specified amount of data to be displayed within a particular unit of measurement (in my case I have 300 pixels being displayed per every inch of my photo). A higher resolution means a higher quality image, but it also means the overall size of the file will be larger. A simple rule of thumb is that for print, keep the resolution set to 300 pixels per inch, and for the web, keep it set to 72 pixels per inch.
I will not be using this image for print, so I’ll change the resolution to 72 pixels per inch (I only need to type 72 for the X resolution value, and the Y resolution value will update automatically when I press the tab key).
4.Set Your Interpolation Quality
The “Interpolation” dropdown (denoted by the red arrow in the image above) is going to determine what method GIMP will use to scale your image either up or down. There are 5 interpolation methods in total in GIMP 2.10, with “none” being the fastest method but producing the lowest quality final image, and with “LoHalo” producing the highest quality final image but taking the most time to complete. I recommend setting your image to either LoHalo or NoHalo, especially if you are scaling your image up or down considerably. For more information on Interpolation, I recommend watching my GIMP tutorial on Scaling Your Images Without Quality Loss.
I went with NoHalo for this image, then clicked the “Scale” button to apply my changes and resize my image.
Once my photo has finished scaling, you can now see that the new dimensions (1920×1280) are displayed at the top of the GIMP window (red arrow). I can re-center and frame my image on the image window by hitting ctrl+shift+J.
5.Export Your Image
Now that your image is scaled, you can either export your image as a JPEG or save it as a .XCF file (GIMP’s native filetype, which will preserve layers but only be usable in GIMP). To export your image, go to File>Export As.
Rename your photo, ensuring it ends in whatever file name you want to save it as (i.e. .jpeg), then click “Export.”
The “Export Image as JPEG” window will pop up. Set the quality of your image (I recommend somewhere between 60-75% if you are using it on a website), then click “Export” again.
You can also simply go to File>Save As to save it as an XCF file, ensuring the filename ends in “.xcf” rather than another file type.
That’s it for this tutorial! If you enjoyed it, you can check out my other GIMP How-to Articles or my GIMP Video Tutorials on my website.