When you upload pictures into WordPress, it automatically makes different sizes of images. You can change the default sizes that WordPress automatically makes.
You can also use WordPress to edit your photos. There is a tool that lets you resize, crop, rotate and flip your photos.
This post tells you how to set or change image size defaults and how to use the WordPress Image Media Tool to re-size or edit your photos.
WordPress default image sizes are Thumbnail, Medium, Large and Full Size. Full Size is the original size of the image.
Some Themes have other images like Medium-large.
You can also put in a Custom Size, but if you do it here, the image itself is not resized. It just looks a different size on the page.
You can change these sizes at Settings > Media.
If you change the settings here, any photos you upload will use the new sizes. It doesn’t change any of the photos that are already there. Any images you uploaded before this will still be whatever size they were uploaded at.
Some Themes want to use specific image sizes. But it is going to make due with whatever size you have told WordPress to make in your Media Settings. Some Themes use the Thumbnails as a header image… not something you would guess. If you make a small Thumbnail or if you are trying to change from a Theme that had small Thumbnail images, you will have blurry pictures used as headers on your Search and Blog home pages.
The uploading tool will make photos smaller, but it won’t make them any bigger.
If the image is the same size as any of the default image sizes, it will still make a copy of the image. This copy can be blurry, so if you are using an image that is the same size as your original image, go to the Display Settings > Size and select Full Size.
Where to Find the Edit Media Tool
If you don’t have any software to edit your images, you can use the Edit Media tool to edit your photos.
There are a few ways to reach Edit Media.
1) From the Media Library, click on the picture you want to edit, then click Edit Image below the picture.
2) From a Page or Post, click Add Media.
Select the photo you want to add, then click Edit Image.
3) Or, from a Page or Post, click Add Media. Then click on the image and click the little pencil to edit. Then select Edit Original.
How to Use the Edit Media Tool
You can Scale the image or Crop, Rotate left, Rotate right, Flip Vertical and Flip Horizontal.
Scale just changes the size of the image without changing anything else.
2560 x 1920 is a pretty common size for a photo. Put in different numbers to make the image smaller without changing anything else. As you put in one number, the other number changes to match the aspect ratio of the existing photo.
This is an easy way to make the image smaller. It will let you make the photo larger, too, but that will almost always make it blurry.
To crop the image, click on Crop and drag the little box to make your selection.
Crop Aspect Ratio
Some common aspect ratios are 9:16, 4:5, 5:7, 3:4, 3:5, 2:3.
Put the aspect ratios you want into the Aspect ratio boxes first. Then click Crop and the lines will stay within the width and height you have told it. You can resize and move the box around.
The aspect ratio is the relationship between the width and height. You can preserve the aspect ratio by holding down the shift key while resizing your selection. Use the input box to specify the aspect ratio, e.g. 1:1 (square), 4:3, 16:9, etc.
So, that’s another way to do it. Hold down the shift key. That’s not the way I do it.
Another method is Selection. When you click Crop and move the little box that shows up, it changes the numbers in Selection. You can adjust it by entering the size in pixels. The minimum selection size is the thumbnail size as set in the Media settings.
You can also crop to a specific size by putting the pixel size into the selection. Then move the box around to what you want.
Rotate and Flip
There are little pictures by these buttons that let you know what they do. You can rotate left or right and you can flip (mirror) horizontal or vertical.
You can choose whether to Apply changes to All image sizes, Thumbnail only or All sizes except thumbnail.
This is really helpful especially with Thumbnails. A lot of Themes use a square Thumbnail. When you drop or upload a picture into the Media Library, it makes a Thumbnail, but if it is square, it may be chopping off part of the picture you want to keep. You can use the aspect ratio to make a square image the size of the thumbnails your Theme uses, then save it as the Thumbnail.
Undo and Restore
If you mess up, you can click Undo.
If you have already clicked Save, Undo is greyed out. But you can still Restore the image.
Jpegs are lossy. Every time you save them, some of the information in the original file is lost. You can end up with a large but blurry file if you keep making changes and re-saving them. Restore the Original Image, make all of your changes and then save.
You really really really cannot make the photo smaller, then try to make it bigger again. It doesn’t work. You get a blurry mess.
Restore throws away all of the changes you have made and goes back to the way it was when you started this time.
Don’t worry if you have already used the photo somewhere else. This creates a new version of the photo with a slightly different number in the actual file name.
If you WANT to change the photo on other posts and pages, you have to go to each page, click on the photo, click on the pencil to edit, click Replace. This will take you to the Media Library. The new version of the image will be there.
You can find every place you have used the photo by using Search Posts or Search Pages from All Posts or All Pages. Just search by the name of the image. It won’t find Featured images*, though.
*Your featured images will always show up as Unattached, so don’t think that means they are clutter and delete them. It has happened.