Bulk Image Resizer

Pixels or percentage

Pixels gives every image the same box: a width, a height or both, in whole pixels from 1 to 10,000. Percentage scales each image by the same amount instead, so a mixed batch keeps its differences — at 50%, a 4000×3000 photo becomes 2000×1500 and a 1200×800 one becomes 600×400 — and every image keeps its proportions. Fit, crop and stretch only apply to pixel sizes; a percentage has no box to fit into.

A percentage can be anything from 1% to 1000%. Above 100% images get bigger but not sharper. The 10,000-pixel limit is checked for each image on its own: if a percentage would take one image past it, that image is refused with its own size in the message rather than quietly made smaller, and the rest of the batch carries on.

Social media and shop sizes

The preset list fills in the size for you: Instagram square (1080×1080), portrait (1080×1350) and story (1080×1920) posts, Facebook and LinkedIn shared images, X and LinkedIn headers, YouTube thumbnails (1280×720) and channel banners, Pinterest pins, a square profile photo, and product photos for Amazon, Shopify, Etsy and eBay. Social sizes crop to fill, because a feed has one exact shape; shop sizes pad the photo on white, because a product must not lose an edge. These are the commonly recommended sizes at the time of writing — platforms do change them, so every number stays editable.

Resizing for print: inches, centimetres and DPI

A screen counts pixels; a printer counts inches. Choose in, cm or mm and give a DPI, and the size is converted for you — at 300 DPI, 4 × 6 inches is 1200 × 1800 pixels and 10 × 15 cm is 1181 × 1772. The DPI is also written into every JPG and PNG, so the file opens in a print dialog or an editor at the size you asked for instead of the 72 DPI most tools leave behind. Fractional sizes such as 3.5 inches are fine; the result is rounded to whole pixels.

Resizing to a file size

Upload forms and marketplaces often cap the file size as well as the dimensions. Switch File size by to Max KB, and each image is resized and then saved as a JPG or WebP at the highest quality that fits under your limit. Not every limit is reachable for a large photo; when one is not, the row says so and shows the smallest size it could make.

Fit, crop, pad or stretch

These are four different answers to the same awkward problem: your images are not all the shape of the box you want them in.

• Fit inside scales the whole image down until it sits within the size you gave. Nothing is lost, but the result is only exactly your size on one side — a 4:3 photo fitted to 800×800 comes out 800×600.
• Crop to fill gives you the exact size every time by scaling up until the box is covered and trimming what hangs over, from the centre. Use it when the images have to line up in a grid; avoid it when the edges matter.
• Pad to exact size fits the whole image inside the box and fills the rest with a background colour — white by default, any colour you pick, or transparent for PNG and WebP. Every output is exactly the same size and nothing is cut off, which is what product listings and photo grids usually need.
• Stretch forces the exact size by distorting the image. It is behind the aspect-ratio switch because it is almost never what you want, but it is occasionally exactly what a spec demands.

Resizing or compressing?

Resizing changes how many pixels an image has. Scaling a photo down usually makes the file smaller too, but that is a side effect: the job here is to get every image to the width, height or shape you need.

If the dimensions are already right and the files are still too heavy, resizing is the wrong tool. The bulk image compressor re-encodes each image at a quality, or to a file size, you choose and leaves its width and height untouched. Many batches need both, in that order: resize to the size the images will actually be shown at, then compress.

Why resize in the browser?

Scaling an image is arithmetic on pixels your computer already has. Sending a file to a server to have that done, then sending it back, is slower for a large batch, costs someone money per image, and puts your files on a machine you do not control. Doing it locally is the reason this tool has no sign-up and no usage limit.

Frequently asked questions

Are my images uploaded anywhere?

No. Resizing happens in your browser using the canvas API. Your images never leave your computer, which is why the tool needs no account and has no usage limit.

What is the difference between fit, crop, pad and stretch?

Fit scales the image so it sits inside the size you give without cropping, so one side may come out smaller than you asked for. Crop fills the size exactly and trims the overflow from the centre. Pad fits the whole image inside the exact size and fills the empty space with a background colour you choose, so every file comes out the same size with nothing cut off. Stretch forces the exact size and distorts the image, which is why you have to turn off aspect ratio to reach it.

Can I resize photos for Instagram, Facebook or YouTube?

Yes. Pick a preset size and the width, height and resize mode are filled in for you — Instagram square, portrait and story, Facebook, X, LinkedIn and YouTube images and banners, a Pinterest pin, and product photos for Amazon, Shopify, Etsy and eBay. Social sizes crop to fill the exact shape; shop sizes pad the image on white so no part of the product is cut off. These are the commonly recommended sizes, and the numbers stay editable if a platform changes them.

Can I resize in inches, centimetres or millimetres for printing?

Yes. Choose in, cm or mm as the unit and enter a DPI — 300 is usual for print. The size is converted to pixels (4 × 6 inches at 300 DPI is 1200 × 1800 pixels), and the DPI is written into JPG and PNG files so they open at the right print size. WebP has no standard place for a DPI, so it is not written there.

Can I resize images to a maximum file size in KB?

Yes. Switch File size by to Max KB and enter a size: each image is resized, then saved as a JPG or WebP at the highest quality that fits under it. If an image cannot get that small even at the lowest quality, its row says so and you get the smallest version. PNG is lossless and has no quality to lower, so choose JPG or WebP as the output format for a size limit.

Can I set only a width, or only a height?

Yes, when you are fitting and keeping the aspect ratio — the other side follows from the ratio. Cropping and stretching describe an exact box, so both numbers are required and the tool will tell you rather than guessing.

How many images can I resize at once?

Up to 200 per batch. They are processed a few at a time rather than all at once, so a large batch will not exhaust your browser memory.

Will small images be blown up to the size I enter?

Not unless you ask. "Don’t enlarge smaller images" is on by default, so in a mixed batch an image already narrower than your width keeps its own size instead of being stretched to it — enlarging adds pixels but no detail, and makes the file much bigger. Turn it off when every image must come out at exactly the same size.

What quality are resized JPG and WebP files saved at?

82% by default, which looks the same as the original on screen at a fraction of the file size. The quality slider changes it for the whole batch. PNG is lossless, so the slider does not affect PNG output.

Will resizing change my file format?

Not unless you ask it to, or unless it has to. JPG, PNG and WebP keep their format by default, and you can convert everything to JPG, PNG or WebP with the format control. BMP, GIF and AVIF are read but cannot be written back — a browser canvas encodes only those three — so they come back as the closest one, keeping transparency where the original had it. Animated GIFs, animated WebPs and APNGs are refused rather than accepted, because a canvas only ever sees the first frame and the animation would be silently lost.

Related reading

Working out a batch workflow? There is a guide to batch image processing, and if you are selling online, see Amazon’s photo requirements.