The short answer
Batch processing means one recipe, many files. You decide the target once: the longest side in pixels, the format, the quality or a maximum size in KB, and maybe a new file name. Then every image goes through exactly the same steps, so a folder of 200 product photos comes out consistent instead of 200 slightly different manual edits.
With the tool below, pick a chain under Chain (for example Web: 1600 px, JPG or Email: 1280 px, max 300 KB), drop your photos, and press Download all as ZIP. If none of the ready chains fits, use Add a step to build your own and Save chain to keep it for next time.
Try it here: Batch Image Processor
Open the full tool pageWhy the order of steps matters
File size depends mostly on the number of pixels and on the compression quality. A 12 megapixel phone photo (4032 x 3024) has about 7.5 times as many pixels as the same photo at 1600 x 1200. If you compress first and resize afterwards, the quality search happens on pixels you are going to throw away, and the resized file is encoded a second time. Resizing first and compressing last gives a sharper image at the same KB.
Shape changes come before size changes. Rotate first if some photos need turning, then crop or pad to the ratio you want, then resize to the final width and height. If you resize to 1080 x 1350 before cropping to 4:5, the crop cuts into an image that is already small, and the result ends up below the size you asked for.
In the processor on this page, the image is decoded once and saved once. The Format, Target size and Rename steps only apply when the file is written, so their position in the list does not matter. The steps that change the picture (Resize to fit, Exact size, Crop to ratio, Padding to ratio, Rotate, Flip) run from top to bottom, and you can move them with the arrow buttons.
Typical chains for shops, blogs, email and social media
These are sensible starting points, not rules. Check the actual limits of the platform you upload to, since they change and differ between services.
| Use | Chain | Why |
|---|---|---|
| Blog or article images | Resize to fit 1600 x 1600, Format JPG quality 80 (or WebP 80) | Wide enough for sharp display on most screens, usually 150 to 350 KB |
| Web shop product photos | Padding to ratio 1:1 white, Exact size 1000 x 1000 or larger, Format JPG 90 | Square tiles line up in the grid and the product is never cut off |
| Email attachments | Resize to fit 1280 x 1280, Format JPG 80, Target size 300 KB | Twenty photos stay around 6 MB, well under common attachment limits |
| Instagram portrait posts | Crop to ratio 4:5, Exact size 1080 x 1350, Format JPG 90 | A 4:5 portrait fills more of the feed than a square; the exact size avoids a second crop |
| Archiving phone photos | Resize to fit 2048 x 2048, Format JPG 85, Target size 500 KB | Converts HEIC to JPG and keeps enough detail for viewing and small prints |
| Fast website, modern browsers | Resize to fit 1920 x 1920, Format WebP 80 | WebP is often 25 to 35 percent smaller than JPG at similar quality |
How to do it step by step
- Choose a ready chain under Chain, or start from Custom chain and use Add a step.
- Set each step: Max width and Max height for Resize to fit, Width and Height for Exact size, Ratio and Color for Padding to ratio, Max size in KB for Target size.
- Put the steps in order with the up and down arrows: rotate, crop or pad, resize. Remove anything you do not need with the cross button.
- Drop the photos in. JPG, PNG, WebP, HEIC, AVIF, GIF and BMP can be mixed in one batch, and each row shows the old and new pixel size.
- Use Compare on one or two files to check sharpness, then press Download all as ZIP.
- Type a name and press Save chain, or use Share with these settings to send the exact same chain to a colleague as a link.
Naming files and keeping the originals
Without a Rename step, each file keeps its original name with the new extension, so IMG_2041.HEIC becomes IMG_2041.jpg. The Rename step adds a Prefix in front, a Suffix after the name and, with Add numbers, a running number such as -01, -02 in the order the files were added. A prefix like spring-catalog- plus a suffix like -1600 tells you at a glance where a file belongs and what size it is.
For websites, short lowercase names with hyphens and no spaces are the safest choice: they work on every server and look clean in links. Descriptive words (red-leather-wallet rather than DSC0042) also help image search a little, because search engines read file names as a small hint about the content.
Always keep the originals. The processor never changes the files on your device; it creates new copies that you download. Store the full size originals in one folder and the exports in another. Every lossy save throws away some detail, so if you need a different size later, start again from the original instead of re-compressing an already compressed export.
Compared with desktop tools
Desktop editors can do the same job, and if you already use one daily they are a good choice. A browser tool wins when you need it on a computer where nothing is installed, on a work laptop without admin rights, or for a one-off job that should not need a learning session.
- Photoshop: record an Action (resize, save as JPG) and run it with File > Automate > Batch, or use the Image Processor script under File > Scripts for simple resize and convert jobs. Very flexible, but setting up the first action takes some practice.
- Lightroom Classic: the Export dialog has resize to fit, JPG quality, a limit on file size and file naming templates, all savable as export presets. Excellent if your photos already live in a Lightroom catalog.
- IrfanView (Windows, free): File > Batch Conversion/Rename handles resize, format, quality and rename patterns in one window. Fast, but HEIC needs extra plugins and the options are spread across several dialogs.
- macOS Preview and Shortcuts: in Preview you can select many images, adjust size for all of them and export the selection; Finder Quick Actions and the Shortcuts app can convert and resize images too. Good for simple jobs, while target sizes in KB and padding to a square need more work.
- Windows: Microsoft PowerToys adds an Image Resizer to the right click menu, which is handy for resizing but does not crop, pad or aim for a file size.
Common problems and fixes
- Files still too big: add a Resize to fit step before Target size. Target size only lowers quality, so a 4000 pixel photo with a 100 KB limit can end up blurry or above the limit.
- Product cut off in square images: use Padding to ratio instead of Crop to ratio, and put it before Exact size.
- Small images got blurry: Exact size enlarges images that are smaller than the box. Use Resize to fit if small images should stay as they are.
- PNG files turned into JPG: a KB target needs lossy compression, so PNG is saved as JPG, or WebP when it has transparency. Remove Target size to keep PNG.
- White background behind logos: JPG has no transparency, so transparent areas are filled with white or with the Padding color. Choose PNG or WebP in Format to keep transparency.
- Sideways photos: phones store a rotation flag that most browsers apply when decoding. If a photo still lies on its side, add a Rotate step for that batch.