Bulk Image Resizer

About resizing images in bulk

Resizing one photo is a solved problem. Nobody has one photo.

They have 180 shots from a shoot that have to go on a website. A folder of product pictures where every one is 6000 px wide. Forty screenshots for a manual. Photos for a property listing that refuses anything over 5 MB. Doing those one at a time is an afternoon, and you will make a mistake somewhere around number sixty.

Drop the whole lot in, set the size once, get a ZIP back.

Three ways to say what "smaller" means

• Fit inside a box *(the default)* — give a maximum width and height, and every image is scaled until it fits inside them. Each one keeps its own shape, so a portrait and a landscape in the same batch both come out right and neither is squashed. This is what an upload limit is actually asking for.
• Percentage — halve everything, or take it to 25%. The right choice when the images are already consistent and you just want them lighter.
• Exact size — force every image to precisely these pixels. Useful for avatars, thumbnails and grid tiles where everything must line up.

Exact size raises a question the other two don't: what happens when the shape doesn't match?

• Crop to fill — fill the frame and trim the overflow. Best for thumbnails, where filling the tile matters more than keeping the edges.
• Pad with a colour — fit the whole picture in and fill the gaps. Best when nothing may be cut off — product shots on white, for instance.
• Stretch — force it, and accept the distortion. Rarely what anyone wants; it's there because occasionally it is.

Never upscale

On by default, and worth leaving on. Blowing a 400 px image up to 1920 px does not add detail — it invents blur and makes the file bigger for nothing.

With it on, a mixed folder behaves sensibly: the big images come down to your limit and the already-small ones are left exactly as they are.

Format and quality

Keep each original leaves JPGs as JPGs and PNGs as PNGs, which is usually right. Or convert the whole batch to JPG (smallest for photos), PNG (lossless, keeps transparency) or WebP (smaller than both, supported everywhere modern).

Quality applies to JPG and WebP. 85% is the sweet spot — visually indistinguishable from the original for almost any photo, at a fraction of the size. PNG ignores it, because PNG is lossless.

Two notes: converting a transparent PNG to JPG fills the transparency with white, because JPEG has no transparency at all. And a GIF comes out as a PNG — resizing an animation with a canvas can only keep the first frame, so it is saved honestly as a still.

Nothing is uploaded

Every image is read, resized and packed inside your browser. No file goes to a server, which for a batch tool means:

• No upload wait — 200 photos start instantly, because nothing is being transmitted
• No total size limit from an upload cap
• Private — client photos, product shots, personal pictures and screenshots stay on your machine
• It works on a slow connection, and offline once the page has loaded

What people use it for

• Getting a shoot ready for a website without opening an editor
• Bringing product photos down to a store's size limit
• Making email attachments small enough to send
• Preparing screenshots for documentation at a consistent width
• Square thumbnails for a grid, all cropped the same way
• Shrinking a holiday folder before backing it up or sharing it

Good to know

• Up to 300 images per run; split a bigger folder into batches
• Each image also gets its own download button in the preview, so you can grab just one without the ZIP
• The first 24 results are previewed; the ZIP always contains everything
• File names are kept, with the extension changed if you changed the format
• Metadata (EXIF, GPS) is not carried over — resizing through a canvas drops it. That is usually welcome; if you need it gone deliberately, Batch Metadata Strip is the explicit tool
• To hit a specific file size rather than a specific pixel size, use Compress Image to Size

How to use it

• Click Click to upload, or drop a whole folder of images onto the box
• Pick Fit inside a box, Percentage or Exact size
• Set the numbers — and the fill behaviour, if you chose an exact size
• Choose the output format and quality
• Press Resize them all, then Download all (ZIP)

Related tools

• Image Resizer — one image, with a live preview
• Image Compressor — make files smaller without changing the pixels
• Compress Image to Size — hit an exact file size in KB
• Crop Image — trim one image by hand
• HEIC to JPG — convert iPhone photos first
• ZIP and Unzip Files — open the ZIP you get back