If you are hunting for the one correct featured image size in WordPress, here is the honest answer up front: there is not a single magic number, because the size your image actually displays at is decided by your theme, not by WordPress itself.
That sounds unhelpful, so let me make it practical. For almost every site, a safe upload is 1200 pixels wide at a 16:9 ratio (1200 by 675), high resolution but compressed, and below I will explain why that works and when you would pick a different size.
Wichtigste Erkenntnisse
- There is no fixed WordPress featured image size; your theme sets the display dimensions, so two themes can show the same upload differently.
- A safe upload is 1200px wide at 16:9 (1200 by 675). It looks sharp on high-density screens and downscales cleanly.
- Die aspect ratio matters more than the exact pixels, because the theme will crop your image to its own ratio if yours does not match.
- WordPress auto-generates several sizes (thumbnail, medium, large) from your upload; the theme chooses which one to show.
- Keep the file small, ideally WebP under about 200 KB, so a heavy featured image does not drag down your Core Web Vitals.
- The 1200 by 630 number you see everywhere is the social-share (Open Graph) size, which is a separate setting from the on-page display.
Why there is no single featured image size
WordPress does not enforce one featured image size. Instead, each theme registers the dimensions it wants using functions like set_post_thumbnail_size() und add_image_size(), which you can read about in the WordPress developer docs. So the “right” size is really whatever your active theme asks for.
This is why the same image can look perfect on one theme and awkwardly cropped on another. One theme might display featured images as wide 16:9 banners, while another uses tall portrait cards, and each will crop your upload to fit its own frame. Knowing that upfront saves you from blaming the image when the theme is the one doing the cropping.
The safe size to upload
For a default you rarely have to think about again, upload at 1200 pixels wide in a 16:9 ratio, which is 1200 by 675. It is large enough to stay crisp on retina and 4K screens, and because it is bigger than most themes display, WordPress can scale it down without it ever looking soft.
| Use case | Suggested size | Ratio |
|---|---|---|
| General blog featured image | 1200 by 675 | 16:9 |
| Doubles as social-share image | 1200 by 630 | ~1.91:1 |
| Full-width hero header | 1920 by 1080 or larger | 16:9 |
| Portrait or card-style themes | Match the theme ratio (e.g. 1200 by 1500) | 4:5 |
If you want your featured image to do double duty as the thumbnail people see when the post is shared, 1200 by 630 at roughly 1.91:1 is the sweet spot, since that matches the social-share ratio closely while still looking fine on the page.
Why ratio matters more than exact pixels
The most common featured-image complaint is not blur, it is bad cropping, and that almost always comes from a ratio mismatch. If your theme wants a 16:9 frame and you upload a square photo, WordPress hard-crops the top and bottom to make it fit, which can lop off heads, logos, or text.
So before you obsess over exact pixels, check the shape your theme uses and match it. Keep the important part of the image near the center too, because that is the area most likely to survive whatever crop the theme applies.
The sizes WordPress creates automatically
When you upload one image, WordPress does not store just that file. It generates several versions so it can serve the right one in the right place, and the defaults are thumbnail (150 by 150), medium (up to 300 by 300), medium_large (768 wide), and large (up to 1024 by 1024).
Your theme then decides which of those generated sizes to display as the featured image, or registers a custom size of its own. That is the whole reason uploading a generously sized original matters: WordPress can always scale down from a big, sharp source, but it cannot invent detail by scaling a small one up.
Keep the file small and the format right
A large dimension is fine; a large file size is not. The featured image is often the biggest thing loading at the top of your post, so a heavy one directly hurts your largest contentful paint and the rest of your Core Web Vitals. Export it as WebP where you can, aim for somewhere under about 200 KB, and always add descriptive alt text.
If you want to change the actual size your theme generates rather than just the file you upload, that is a different job, and I walk through it step by step in how to change the featured image size in WordPress.
What about the social sharing image?
The famous 1200 by 630 number is the Open Graph image size, the thumbnail shown when your post is shared on social platforms. That is set separately from the on-page featured image, usually by your SEO plugin, so do not confuse the two even though they often use the same picture.
So what size should your featured image actually be?
In my view, upload at 1200 by 675 in 16:9, match that ratio to whatever your theme actually displays, and compress it to WebP. That one habit covers the vast majority of sites and saves you from the cropping and blur problems that send people searching for a magic number in the first place.
The only time I would deviate is when a theme clearly wants a different shape, like a tall portrait card or a wide full-screen hero, in which case I match the theme rather than fight it. Get the ratio and the file size right, and the exact pixels stop mattering.
Änderungsprotokolle
01 Jul 2026
- Rewritten to give the real answer: the featured image size depends on the theme, with a safe 16:9 upload, a sizes table, and the difference between the on-page image and the social-share size.
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