Image sizes, cropping & alt text
Understand how WordPress handles image sizes and cropping, and learn how to write good alt text for accessibility and SEO.
When you upload an image to WordPress, a few things happen automatically. WordPress creates several smaller copies of the image for different uses — and it's helpful to understand why. This guide also covers alt text, which makes your images accessible to everyone.
Quick summary
WordPress automatically generates multiple sizes of every uploaded image: thumbnail, medium, large, and full. You can edit the focal point for cropping in the media library. Alt text is the written description of an image — it's required for accessibility and helps with SEO. Always add alt text when uploading images.
Why WordPress creates multiple image sizes
When you upload a photo, WordPress doesn't just store the original. It creates several copies at different dimensions. This allows WordPress to show the right size for the right context — a small thumbnail in a blog list view, a medium image inside a post, and a large image in a gallery.
The default sizes WordPress creates are:
| Size name | Default dimensions |
|---|---|
| Thumbnail | 150 × 150 px (cropped to square) |
| Medium | Up to 300 × 300 px |
| Medium Large | Up to 768 px wide |
| Large | Up to 1024 × 1024 px |
| Full | The original file at its uploaded dimensions |
Your theme and any page builder plugins may register additional custom sizes.
Storage tip
All these copies take up disk space. This is normal and expected. If storage becomes an issue, a plugin can clean up unused size copies — ask us if you need help with this.
How the thumbnail crop works
The thumbnail size is the only one WordPress crops automatically (cutting out the center of the image). All other sizes scale proportionally without cropping.
If your image has an important subject — a person's face, a product — that's not in the center, the thumbnail may cut it off. You can adjust where WordPress crops:
Go to Media in your dashboard and click the image you want to adjust.
Click "Edit image" in the attachment detail panel. This opens the image editor.
Select the thumbnail checkbox on the right side, then draw a selection on the image by clicking and dragging to choose your preferred crop area.
Click "Save." The thumbnail is now regenerated with your chosen crop.
What is alt text?
Alt text (short for "alternative text") is a written description of an image. It serves two important purposes:
- Accessibility — Screen readers (used by visually impaired visitors) read the alt text aloud instead of showing the image. Without alt text, those visitors have no idea what the image is.
- SEO — Search engines can't "see" images, so they rely on alt text to understand what an image shows. Good alt text helps your images appear in Google Image Search.
Alt text is required, not optional
Missing alt text makes your site less accessible and less findable. WordPress will let you publish without it, but you should always add it. If you need to add alt text to many existing images, we can help audit and update them.
How to write good alt text
Good alt text describes what the image shows, concisely and specifically.
Ask yourself: "If this image didn't load, what would a visitor need to know?"
| Situation | Poor alt text | Good alt text |
|---|---|---|
| Team photo | "photo" | "Three women working together at a conference table in a bright office" |
| Product shot | "image1" | "Blue ceramic coffee mug with a brushed copper handle" |
| Decorative divider | (any text) | Leave blank — decorative images get empty alt text |
| Logo | "logo" | "Maple Street Bakery logo" |
| Chart | "chart" | "Bar chart showing a 40% increase in sales from 2023 to 2024" |
Keep it under 125 characters. Screen readers may cut off longer descriptions.
Don't start with "Image of" or "Photo of" — screen readers already announce it as an image.
Decorative images get empty alt text. If an image is purely decorative (a background texture, a divider line) and adds no information, leave the alt text field blank. This tells screen readers to skip it.
How to add or edit alt text in WordPress
Go to Media in your dashboard and click the image you want to update.
Find the "Alternative Text" field in the detail panel on the right side of the screen.
Type your description into the field.
Click "Update." The alt text is saved. It will apply everywhere this image is used on your site.
You can also set alt text while inserting an image into a page or post — the image block in the editor has an alt text field in its settings panel.
What image dimensions should you upload?
Uploading a 6000 × 4000 px photo from your camera is unnecessary — WordPress will scale it down anyway, but the large original still sits on your server. A good rule of thumb:
- Full-width banner images — 1920 px wide at most
- Content images — 1200 px wide is usually plenty
- Logo — match the size you want it to display, or ask us for guidance
See image basics for your website and how to compress images for more on preparing images before you upload.
Common questions
Related guides
- The media library explained
- How to upload images and files
- How to add images to a page or post
- Alt text explained
- Image basics for your website
- Image SEO & alt text
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