Percentage resizing
Apply the same proportional reduction to every image in a batch, from 1% to 100% of the displayed dimensions.
Resize images online and reduce file size
Resize up to 25 JPEG, PNG or WebP images by percentage or pixel limits. Preserve aspect ratio, keep the input format and optimise every output directly in your browser.
25images per batch25MBmaximum per image100%maximum scale, no upscaling
Resize and optimise
Choose the new size, then add your images
No upload
Drop images hereor choose files from your device
JPEG, PNG or WebP · Up to 25 images · 25MB per image
Original size0 B
Output sizePending
Size changePending
Proportional Aspect ratio stays lockedOptimised Output uses the format codecPrivate Files stay on your device
Resize and optimise together
Reduce dimensions and encoding weight in one workflow
Smaller pixel dimensions usually create a meaningful file-size reduction. ImageOptimise then applies the approved codec for the original format, avoiding a separate compression step.
Pixel limits
Enter a maximum width, height or both. Each image fits inside those limits without cropping or distortion.
Aspect ratio protected
Width and height remain linked automatically, preventing stretched faces, products, graphics or screenshots.
Optimised downloads
The resized result keeps its JPEG, PNG or WebP format and is re-encoded with the approved optimisation settings.
How to resize an image
Choose, add and download in three steps
Settings lock while a batch is active, so every image follows the same resize rule.
Choose percentage or pixels
Use a percentage for consistent proportional scaling, or enter maximum pixel dimensions for a bounding-box fit.
Add up to 25 images
Drag supported files into the tool or browse your device. Resizing and optimisation begin automatically.
Review and download
Check original and output dimensions, file sizes and the genuine size change, then download individually or as one ZIP.
Format-aware output
Resize JPEG, PNG and WebP without changing format
The resize tool keeps the source format and uses a suitable codec after high-quality resampling. This protects transparency where the input format supports it.
Resize JPEG photographs
JPEG output uses progressive MozJPEG quality 77 after resizing, providing the same tested visual-quality and file-size balance as the approved compressor.
Resize PNG graphics
PNG output remains lossless at its new dimensions. Transparent pixels are preserved and the generated PNG is processed with OxiPNG.
Resize WebP images
WebP output uses libwebp quality 80 with full alpha quality, supporting photographs, graphics and transparent content.
Dimensions, quality and file size
Efficient resizing can make images much lighter
Reducing both width and height has a larger effect than the percentage alone may suggest. An image resized to 75% width and 75% height contains about 56% of its original pixel area. At 50% width and height, the output contains about 25% of the original pixel area.
ImageOptimise uses high-quality browser resampling before format-specific encoding. The tool does not upscale because enlargement cannot restore missing source detail and belongs in a separate quality-focused workflow. Results vary by image detail, dimensions, source encoding and selected resize amount.
Keep original master files separately. Review important resized images before replacing production assets, especially where exact print dimensions, colour profiles or metadata matter.
Current optimiser safeguards
✓Aspect ratio is always preserved.
✓Images are never automatically enlarged beyond their displayed source dimensions.
✓The original JPEG, PNG or WebP format is retained.
✓File-size changes are reported honestly, including an unusual larger result.
Practical resizing
Create appropriately sized images for digital use
Serving or sharing an image at far more pixels than needed wastes transfer size, storage and processing time.
Website content
Fit photographs to the maximum width used by a webpage before uploading them to a CMS.
Product catalogues
Standardise product-image bounds while keeping portrait and landscape aspect ratios intact.
Email campaigns
Prepare campaign graphics at more appropriate dimensions before adding them to an email platform.
Reports and slides
Reduce oversized camera images before placing them into documents or presentations.
Portfolio previews
Create lighter display copies while retaining separate original master files.
Batch handovers
Apply one proportional rule to a mixed batch and download every result together.
Private in-browser resizing
Your image files stay in the current tab
The browser decodes, resamples and re-encodes supported images on your device. Image bytes, filenames and resize settings are not sent to an ImageOptimise image-processing server.
- No account or image upload endpoint is required.
- Each browser tab has an independent temporary batch and settings.
- Different devices on the same network cannot see one another’s images.
- Clear All or close the tab to end the temporary session.
Image resize questions
Frequently asked questions
Important details about proportions, pixel limits, optimisation and privacy.
Are resized images also optimised?＋
Yes. After high-quality resizing, JPEG uses MozJPEG quality 77, PNG uses lossless OxiPNG processing and WebP uses libwebp quality 80 with full alpha quality.
Does the tool preserve aspect ratio?＋
Yes. Aspect ratio is always locked. Percentage mode scales width and height equally, while pixel mode fits each image inside the maximum dimensions without stretching.
Can I resize by exact pixels?＋
You can enter a maximum width, maximum height or both. The image is fitted within those limits, so one dimension may be smaller than the entered maximum when required to preserve its proportions.
Can the tool enlarge an image?＋
No. This resize tool does not upscale beyond the decoded source dimensions. Enlarging an image cannot recreate missing detail and will be handled by a separate future tool.
Will PNG and WebP transparency remain?＋
Yes. Transparent content remains supported when resizing PNG and WebP images. JPEG inputs remain JPEG and do not contain transparency.
Will every resized image be smaller?＋
Most meaningful reductions in dimensions will also reduce file size, but results depend on the source and format. Any larger result is reported honestly rather than described as a saving.
What happens at 100%?＋
The pixel dimensions remain unchanged, but the image still passes through the approved optimisation path. If the candidate is not smaller, the original is retained.
How many images can I resize?＋
You can process up to 25 JPEG, PNG or WebP images per batch, with a maximum individual file size of 25MB.
Choose your new dimensions
Resize images now
Resize and optimise your next image batch
Set a percentage or pixel limit, then add up to 25 images from your device.