KB or MB targets
Choose one maximum size that applies separately to every image in the current batch.
Compress images to a specific KB or MB size
Set one maximum size for each JPEG, PNG or WebP image. ImageOptimise searches for a safe result and reports honestly when the requested target cannot be reached.
25images per batch25MBmaximum per image10KBminimum target
Compress to a target
Choose the maximum size for each image
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
Total reductionPending
Honest Reached or closest safe resultQuality floor No extreme encodingPrivate Files stay on your device
A target with safeguards
Aim for a target with clear safeguards
Target-size compression tests bounded quality levels and can reduce dimensions proportionally when necessary. It never labels an oversized result as successful.
Bounded quality search
JPEG and WebP stop at a quality safeguard instead of continuing into extreme visible damage.
Optional smart resizing
Smart target may reduce dimensions proportionally only when encoding alone cannot reach the requested size.
Honest outcomes
Every result is labelled Target reached, Already under target or Closest safe result.
How it works
Set, add and review in three steps
Settings lock while a batch is active so every result follows the same target and strategy.
Set the target
Enter a value from 10KB to 25MB and choose Smart target or Keep dimensions.
Add your images
Add up to 25 supported files. The bounded search starts automatically in browser workers.
Check the outcome
Review the actual output size, dimensions and target status before downloading individually or as one ZIP.
Format-aware target search
Different formats need different target strategies
The source format remains unchanged. JPEG and WebP support bounded quality searching; PNG stays lossless and may need proportional resizing for a demanding target.
JPEG target compression
Progressive MozJPEG searches from quality 82 down to a protected floor of 55, then Smart target can reduce dimensions if required.
Lossless PNG targets
OxiPNG remains lossless. Smart target can reduce pixel dimensions when lossless encoding alone cannot reach the requested size.
WebP target compression
libwebp uses the same bounded quality range with full alpha quality, preserving transparent WebP content.
Quality and target accuracy
A target should not override sensible quality
Some targets are impossible at the original dimensions without severe visible damage. Keep dimensions returns the closest result at the quality floor. Smart target may reduce dimensions proportionally and retry, making demanding targets more achievable.
The output may finish noticeably below the maximum because the search uses a small number of bounded attempts to remain responsive. An image already below the chosen target is retained without unnecessary re-encoding.
Keep original master files separately. Very small targets are unsuitable for large detailed images unless reduced dimensions are acceptable.
Current optimiser safeguards
✓No target is falsely reported as reached.
✓JPEG and WebP do not go below quality 55.
✓Smart resizing preserves aspect ratio and never upscales.
✓PNG and WebP transparency remains supported.
Practical target sizes
Prepare images for systems with upload limits
A known maximum can be useful for forms, portals, email platforms and website performance budgets.
Application portals
Prepare images before using a portal with a stated per-file limit.
Email campaigns
Keep campaign images within an internal transfer-size budget.
Website uploads
Create lighter assets for CMS upload policies and page-weight targets.
Marketplace listings
Prepare product images for services with maximum file sizes.
Documents and slides
Reduce oversized photographs before embedding them into other files.
Batch preparation
Apply one target consistently and download completed results together.
Private target processing
The search runs inside the current browser tab
Images are decoded, tested and encoded locally. Image bytes, filenames, target settings and results are not sent to an ImageOptimise processing server.
- No account or image upload endpoint is required.
- Each tab keeps an independent temporary batch.
- Different devices on the same network cannot see one another’s files.
- Clear All or close the tab to end the temporary session.
Target-size questions
Frequently asked questions
Important details about targets, dimensions, quality and format behaviour.
Will the output always match the target exactly?＋
No. The target is a maximum rather than an exact byte count. A successful output may be smaller, while an unsafe or impossible request is labelled Closest safe result.
What is Smart target?＋
Smart target first searches safe encoding quality. If that is insufficient, it reduces width and height proportionally and retries without upscaling.
What does Keep dimensions do?＋
It protects the decoded width and height. If safe encoding cannot reach the chosen size, the closest result is returned honestly above the target.
Why is the minimum JPEG or WebP quality 55?＋
The floor prevents the engine from chasing a number through extreme visible degradation. It is a safeguard, not a promise of identical appearance.
Can PNG reach any target losslessly?＋
No. Lossless PNG compression has limits. Smart target may reduce dimensions; Keep dimensions reports the closest safe lossless result.
What happens when an image is already smaller?＋
The original file is retained and labelled Already under target, avoiding unnecessary quality loss.
Does transparency remain?＋
Yes for PNG and WebP. JPEG does not support transparency.
How many files can I process?＋
Up to 25 JPEG, PNG or WebP images per batch, with a maximum of 25MB for each input.
Choose your maximum
Compress to target now
Compress your next batch to a target size
Set a KB or MB maximum, choose a strategy and add up to 25 images.