Bulk Image Resizer: Resize Many Images Without Uploading

The bulk image resizer resizes up to ten images in one pass, entirely inside your browser. Choose the files, set a width, optionally set a height, pick an output format, and download every resized image as a single ZIP. The pictures never leave your device: the resizing happens on a canvas, and the ZIP is assembled locally.

That last point is the reason to use this tool rather than a server-based converter. If you are working with client photos, medical images, unreleased product shots or anything under an NDA, uploading a batch to an unknown server is a real decision. Here there is no upload of the image data for the resize itself, which removes the question.

#What "bulk" means here

The limit is ten images per run. Each file can be up to 5 MB, and the combined selection must stay under 15 MB. That is enough for a product grid, a blog post's image set, or a batch of screenshots — not for a thousand-photo archive. If you need a larger batch, run it in groups of ten.

Accepted inputs are JPG, PNG, WebP, GIF and BMP. Output can be JPG, PNG or WebP. The resize is done in the browser, and the tool packages the results with a filename suffix so the originals are not confused with the resized copies.

#How to bulk resize images

1. Open the bulk image resizer.
2. Select up to ten images. The tool shows thumbnails and the combined size.
3. Enter a width in pixels, from 16 to 8192. This is required.
4. Optionally enter a height. With width alone, the height follows each image's own aspect ratio. With both, each image is scaled down to fit inside the box without stretching or enlarging.
5. Choose the output format: JPG, PNG or WebP.
6. Set the quality for JPG or WebP. The slider runs from 1 to 100 and defaults to 85.
7. Optionally change the filename suffix. The default is -resized.
8. Press Run, then download the ZIP.

The result block confirms how many images were resized, the output dimensions, the total size before and after, and the percentage saved. The download is produced in the browser, so it is available immediately.

#Width only vs width and height

The tool never stretches an image to force it into the exact box. That is deliberate: stretched images are a common cause of distorted faces and squashed logos. If you genuinely need an exact width and height, crop first with the image cropper, then resize the cropped result.

Images are also not enlarged. If the source is 600 pixels wide and you ask for 1200, the output stays at 600 rather than inventing pixels. That keeps the result sharp, but it can surprise you if you expected a larger file.

#Choosing an output format

• JPG is the safe default for photographs. It is small and universally supported, but it has no transparency.
• PNG is the right choice for screenshots, logos and images that need transparency. Files are larger, especially for photos.
• WebP gives the smallest files for both photos and graphics and supports transparency, but a few older apps cannot open it.

If you are resizing for a website, WebP at quality 80–85 is usually the best size-to-quality trade. If the destination is a printer or an older desktop app, JPG is safer. PNG is for flat graphics and anything that needs an alpha channel.

#Common problems and fixes

The images are not the size I asked for. The tool preserves aspect ratio and never enlarges. A 400-pixel-wide source asked for 1200 stays at 400 when a height is also set; with width only, it may upscale depending on the source. Check the reported output dimensions.

The images are distorted. This should not happen with the default settings. Distortion usually means a crop or a separate tool forced an exact size. Use width only, or set both values and let the image fit inside the box.

The batch is rejected. Check three limits: no more than ten files, each under 5 MB, and the combined selection under 15 MB. A single oversized file stops the batch.

The ZIP is not downloading. Large canvases and many images can be memory-heavy in a browser tab. Try fewer images per run, close other tabs, or use a desktop browser rather than a mobile one.

Transparency turned black. JPG has no alpha channel. If the source is a transparent PNG, choose PNG or WebP output instead of JPG.

The file size did not drop much. Resizing reduces pixels, but the output format and quality dominate the final size. A PNG of a photo will still be large. Switch to JPG or WebP, or lower the quality.

Animated GIFs lose their animation. The resize works on a still frame. Use a dedicated animation tool if motion matters.

#Tips for a clean batch

• Standardise the width. For a product grid, a consistent width with varying heights is usually better than forcing identical dimensions.
• Sort your files before selecting. The ZIP preserves the order you add them, which makes matching them back to a list easier.
• Use a suffix. Keeping -resized in the filename prevents accidentally overwriting or confusing the originals.
• Resize, then compress. If the output is still too large, the Image Compressor can reduce it further, or choose a lower quality here.
• Keep the originals. The resized set is a delivery copy. Store the full-resolution sources for print or future crops.
• Use the right device. A desktop browser has more memory than a phone, which matters for ten large images at once.
• Check one image before the whole batch. A quick look at the first result catches a wrong width or format before you process everything.

#Privacy and how the browser workflow differs

A server-based resizer uploads each file, processes it, and sends back a download. That is fine for many images, but it means the file exists on someone else's machine for a while. This tool does the work locally: the file is read into a canvas, resized, encoded, and added to a ZIP in memory. The image data is not sent to the server for the resize.

That makes it a better fit for sensitive material and for large files on a slow connection. The trade-off is that the browser's memory is the limit, and a very large batch or a very large canvas can fail where a server would not.

#Frequently asked questions

#Bottom line

Bulk resizing is mostly about consistency: one width, one format, one ZIP, and no upload. Set a width, leave the height blank to preserve each image's proportions, and choose WebP or JPG for web delivery. Start with the bulk image resizer, check the output dimensions on the first run, and keep the originals for anything that may need a larger version later.