Resize Many Images at Once in Your Browser

One Rule, Whole Batch

Modern cameras and phones produce images far larger than most uses require, and resizing forty of them one at a time is an afternoon you will not get back. This tool applies the same resizing rule to a whole set of JPG, PNG, and WebP images at once. Scale everything by a percentage, or set a target width or height; the results arrive as resized_images.zip, keeping their original filenames and formats. Worth being clear about upfront: this resizes, it does not crop. Every image still shows exactly what it showed before, just at different pixel dimensions.

Open Bulk Image Resizer

When a batch resize helps

Preparing photos for a web gallery: full-resolution originals slow pages badly; a consistent width across a set makes a gallery load and lay out predictably.
Getting a batch under an email limit: twenty photos at phone resolution will not attach; the same twenty at half scale usually will.
Producing catalogue thumbnails: a uniform width across product images keeps a grid tidy.
Sending photos to family: nobody needs forty-megapixel originals to look at pictures on a phone.
Standardising screenshots: a set captured on different displays at different resolutions can be brought to one common width.

Decode, redraw, re-encode

The tool uses the browser's own image and canvas capabilities rather than an external image-processing library. Each image is decoded, drawn onto a canvas at the new dimensions your settings produce, and encoded back into a file. Images are processed sequentially, one after another, which keeps memory use manageable on a long list. JSZip then packages the results into a single archive.

Three details follow from that re-encoding step:

JPEG and WebP are encoded at quality 0.85. That is a high setting, but it means these formats are re-compressed rather than simply copied. PNG, being lossless, is not affected by that quality value in the same way.
A 100% resize is still a re-encode. Leaving the percentage at its default does not hand back your original files untouched; the images pass through the same decode-and-encode cycle, so results are not guaranteed to be byte-identical to what you put in.
Re-encoding may drop metadata. EXIF such as capture date, camera settings, and GPS coordinates is often not carried into a canvas-produced file. Keep your originals if that data matters.

The three modes

Percentage scale

Multiplies both dimensions by your figure, between 10% and 200% (default 100). Proportions are always preserved. A 4000×3000 photo at 50% becomes 2000×1500. Best when images have varying sizes and you want them all reduced by the same factor.

Target width

Sets a fixed pixel width. With the aspect lock on, height is calculated proportionally so each image keeps its shape. With the lock off, height stays as it was, which stretches the picture. The mode for a gallery where every image must share a width.

Target height

The same in the other axis. With the lock on, width is calculated proportionally; with it off, the original width stays while the height changes. The mode for a fixed-height banner or row.

Values above 100%, or target dimensions larger than the source, enlarge images. Enlarging cannot add detail that was never captured, so upscaled results look softer. The 10–200% range allows it, but it is rarely a good idea. The aspect-ratio lock is on by default; it governs the width and height modes, and in percentage mode proportions are preserved regardless.

Step by step

Select the images

Add several JPG, PNG, or WebP files at once. Check that no two share a filename, which can conflict inside the archive.

Choose a mode and value

Percentage (10–200), target width, or target height in pixels. Leave the aspect-ratio lock on unless you specifically want to distort the images.

Run and download

Images are handled one after another, so a long list takes proportionally longer. Download resized_images.zip and check a couple of results.

What the archive keeps

Filenames are preserved. beach-sunset.jpg goes in and comes out as beach-sunset.jpg, which matters when your images are already referenced by name somewhere.

Formats are preserved. A JPG stays a JPG, a PNG stays a PNG, a WebP stays a WebP. This is not a format converter, so mixing formats in one batch is fine and each file comes back as what it was. Dimensions follow your chosen mode, applied identically to every image, with no per-image settings.

Choosing a mode for the job

Web gallery or grid: target width with the lock on. Consistent width makes a layout behave; varying heights is normal and usually fine.
Reducing everything for email or storage: percentage scale. It handles a mixed set sensibly without you knowing any individual image's dimensions.
Fixed-height banner or row: target height with the lock on.
Exactly one size in both dimensions: no single setting achieves that without distortion, because sources have different proportions. Crop each to a common ratio first with Crop Image, then resize the batch.

Limitations worth knowing

This is not cropping: framing and composition are untouched. To change what an image shows, use the Crop Image tool.
Unlocking the aspect ratio distorts images: faces stretch and circles become ovals. The option exists for the occasional case where it is wanted; most of the time, leave it on.
No quality slider and no target file size: JPEG and WebP use a fixed quality of 0.85, and dimensions are the only lever you have.
No per-image control, cropping, watermarking, rotation, or format conversion: one setting applies to the whole batch.
Duplicate filenames can conflict: two files with the same name, a common result of selecting from multiple folders, may collide inside the archive. Rename before you start.
Animated WebP is not something to rely on: canvas processing typically works from a single frame, so test before assuming an animated file survives intact.
Memory is the practical ceiling: there is no coded limit, but every file is decoded and the archive assembled in the browser, so very large batches may be slow or fail on a modest device. Splitting into groups is reliable. HEIC is not accepted; convert Apple photos first with the HEIC to JPG or PNG tool.

Privacy and data handling

File contents are processed in browser memory and are not sent to WeConvertFiles for conversion. Resizing uses the browser's built-in canvas, and JSZip is downloaded from a third-party CDN when needed, so the workflow is not described as fully offline.

Zoho PageSense may collect consented site-usage data such as visits, clicks, scrolling, referrer, device information, and conversion events. PageSense is not given the selected images.

Troubleshooting

Some images look stretched

The aspect-ratio lock was disabled. Re-run the batch from your originals with it enabled.

A file is missing from the archive

Check for duplicate filenames in your selection; two identically named files may conflict inside the ZIP. Rename and run again.

The resized images look soft

Either they were enlarged beyond their original dimensions, or reduced very heavily. Neither is recoverable; work from higher-resolution sources where possible.

The photos lost their dates and locations

Re-encoding through a canvas generally does not carry EXIF data across. Your originals still have it.

I set 100% and the files still changed size

Every image passes through decode and re-encode regardless of the percentage, and JPEG and WebP are re-compressed at quality 0.85. A 100% pass is not a copy operation.

Frequently asked questions

Does resizing crop anything off my photos?

No. The entire image is preserved, the same scene and framing, with fewer or more pixels. Cropping is a separate operation that discards part of the picture.

Can I convert formats at the same time, say PNG to JPG?

No. Each image comes back in the format it went in as. Format conversion is a different job and would need a different tool.

Why is the quality fixed at 0.85 for JPEG and WebP?

There is no exposed setting for it. 0.85 is a high value that keeps images looking clean while reducing file size, and it applies to every JPEG and WebP in the batch. PNG is lossless and is not affected by that value in the same way.

What happens if I resize an image larger than its original size?

The pixels are interpolated, so the browser invents intermediate values. The file gets bigger without gaining real detail and edges look softer. The 200% ceiling permits it, but starting from a larger original is always better.

How many images can I process at once?

No limit is coded in, so the honest answer is as many as your device's memory allows. Batches of a few dozen are more dependable than several hundred, particularly with high-resolution photos.

Can I apply different sizes to different images in one run?

No. One setting applies to the entire batch. Group images that need the same treatment and run each group separately.

Shrink a whole folder of images in one pass

Add your JPG, PNG, and WebP files, pick a mode, and download resized_images.zip with every filename and format preserved.

Use Bulk Image Resizer