WordPress added “-scaled” to your photo — the big-image threshold

2026-11-04

You uploaded a photo to WordPress and the image URL ends in -scaled.jpg. You didn't ask for anything to be scaled. WordPress did it on its own, by design, and the rule behind it is short and documented.

What the documentation says

The WordPress developer reference for the big_image_size_threshold filter (checked 2026-10-08) states:

• The threshold value in pixels has a default of 2560.
• "If the original image width or height is above the threshold, it will be scaled down. The threshold is used as max width and max height."
• The scaled-down image "will be used as the largest available size".
• The filter was introduced in WordPress 5.3.0, and returning false from it disables the scaling.

The -scaled suffix in the file name is that scaled-down copy. A 4000×3000 phone photo, for instance, has a width above 2560, so WordPress makes a smaller version — and that is what your posts use as the biggest size.

Why you might want to do it yourself

Turning the threshold off needs code in your theme or a plugin, and many people can't or shouldn't touch that. The other route needs no code at all: upload images that are already no larger than 2560 pixels on either side. Then nothing is above the threshold and the step doesn't apply. Doing the resize yourself has real advantages:

• You choose the size. If your theme's content column never shows images wider than 1600 pixels, there's no reason to store 2560.
• You choose the quality, and see the result before it's uploaded.
• Smaller uploads go up faster and take less room in your media library.

Resizing a whole batch by the long side

Blog photos are usually a mix of landscape and portrait, which is why "resize to a width" is the wrong instruction — it would make every portrait photo enormous. In our Batch edit tool:

1. Drop in the photos for the post.
2. Switch on Resize and set Based on to Long side. Enter 2560, or the smaller width your theme actually needs. The long side of every photo — width for landscapes, height for portraits — becomes that number, and the short side follows the photo's own proportions.
3. Leave Only shrink, never enlarge ticked, so a photo that is already small isn't blown up.
4. Compress is on by default; Recommended quality is right for the web.
5. Use Download all for one ZIP, then upload as usual.

Because WordPress scales only when a side is above the threshold, a long side of exactly 2560 is fine. All the processing happens in your browser — nothing goes to any server but your own site when you upload.

One thing to check before uploading: the file names

Batch edit adds _edit to file names, so harbour.jpg becomes harbour_edit.jpg. WordPress builds the attachment's URL from the file name. If you care about clean image URLs, rename the files before uploading. Names with accented or non-Latin characters come back as image_N_edit.jpg — another reason to give images plain, descriptive names.

What WordPress still does

Pre-resizing only avoids the big-image step. WordPress still generates its usual smaller intermediate sizes for each upload; that is separate behaviour and not affected by what we've covered here.

What we deliberately don't do

We don't offer a "WordPress preset". The 2560 default can be changed by any site's code, and the right size depends on your theme. A tool that bakes one site's number into a button is a tool that is quietly wrong for everybody else; you type the number, and you know where it came from.

The short version

• WordPress (5.3+) scales uploads whose width or height is above 2560 px by default, creating the "-scaled" copy (developer reference, checked 2026-10-08).
• Upload images no larger than 2560 px on either side and the step doesn't apply.
• Batch edit: Resize by Long side, shrink-only, compress at Recommended.
• Rename the _edit files first if image URLs matter to you.