Bulk Image Resizer: Resize Many Images at Once

Two ways to resize a batch

Percentage (default 50%) scales every image by the same factor. A 4000 px wide photo becomes 2000 px and a 1200 px screenshot becomes 600 px. Each keeps its own shape. Use this when the images are similar and you simply want them all smaller.

Dimensions (default 800 x 600) gives a width and height. With "keep aspect ratio" on, each image is scaled to fit inside that box without distortion, so a landscape photo touches the width limit and a portrait touches the height limit. Leave one box empty to fix only the width or only the height. With the ratio off, every image is stretched to exactly the size you type, which distorts any image that does not already have that shape.

How the resampling is done

This tool uses the pica library, which resizes with a Lanczos filter and then applies a light unsharp mask to restore some crispness lost when shrinking. When an image is made much smaller, this generally keeps fine lines and text more legible than a single quick canvas scale. The single-image Image Resizer uses the browser's built-in high-quality scaling instead.

Lanczos resampling is still interpolation. Enlarging images (a percentage above 100% is not offered here, but a dimension box larger than the original is allowed) makes them softer, not more detailed.

Output and downloads

Formats: WebP (default), JPG or PNG, at quality 0.92 for WebP and JPG. PNG is lossless.
Names: each file keeps its name with -resized added.
ZIP: "Download all" builds a ZIP in your browser. Single files can be saved from their cards.
Transparency survives in PNG and WebP; transparent pixels turn black in JPG.
Metadata such as EXIF and colour profiles is not copied to the resized files.

Changing any setting clears previous results, so a ZIP never mixes two different sizes.

Planning a batch

Mixed orientations? Use dimensions with the ratio locked, so portraits and landscapes both fit the same box.
Need identical output sizes for a grid? Crop each image to the same shape first; resizing alone cannot make different shapes identical without stretching.
Still too heavy? Run the ZIP contents through the Bulk Image Compressor.

Where the processing happens

Images are resized one after another in your browser, and the ZIP is created locally. Nothing is uploaded.

Questions about this tool

Can I set only a width?

Yes. In dimensions mode, leave the height empty and keep the ratio locked. Every image gets that width and its own proportional height.

I have 50 photos for my website. How do I resize them all at once?

Add all the photos, choose Dimensions, type the width you need (for example 1200), leave the height empty and keep the ratio locked. Every photo gets that width with its own height. Then press Download All (ZIP).

My photos are a mix of portrait and landscape. How do I make them all fit the same space?

Use Dimensions with the aspect ratio locked and enter both a width and a height. Each photo is scaled to fit inside that box without stretching, so landscapes touch the width limit and portraits touch the height limit.

How do I make all my photos half their size?

Choose Percentage and keep it at 50%. Every image is halved in width and height and keeps its own shape.

Will the file names change?

Each file keeps its name with -resized added at the end, so you can tell the new files from the originals.

I changed a setting and my results disappeared. Why?

Results are cleared on purpose when a setting changes, so a ZIP never mixes images of different sizes. Process the batch again with the new setting.