Image Compressor
Shrink image file size with a live preview — before you even click compress.
Also known as: Photo compressor, Image size reducer, Picture compressor
How it works
- 1Upload one or more images — JPG, PNG, WEBP, and most other formats work.
- 2Pick an output format (JPEG or WEBP for adjustable compression, PNG to stay lossless).
- 3Drag the quality slider and watch the estimated file size for your first image update instantly.
- 4Click Compress — a single image downloads directly, and multiple images download together as a ZIP.
Why use Image Compressor
Live size preview
See the estimated compressed size of your first image update in real time as you drag the quality slider — before committing to anything.
Honest about PNG's limits
Tells you plainly when a lossless format like PNG won't shrink much, instead of promising savings it can't deliver.
Convert while compressing
Switch a PNG or JPEG to WEBP in the same step for the biggest realistic size reduction on photos.
Batch compression
Compress a whole folder of images at once and get a single ZIP file back.
Adjustable quality
Fine-tune the quality-to-size trade-off with a slider instead of a fixed "high/medium/low" preset.
Nothing uploaded
Every image is re-encoded locally in your browser tab.
Who uses Image Compressor
Speeding up a website
Shrink photo file sizes before adding them to a web page so it loads faster.
Fitting an email attachment limit
Compress a batch of photos so they fit under a mail provider's attachment size cap.
Saving phone storage
Shrink a folder of camera photos before archiving or backing them up.
Meeting an upload size cap
Reduce an image below a form or portal's maximum file size before submitting it.
Preparing social media images
Compress photos before posting, since most platforms recompress large files anyway.
Bulk-shrinking a photo archive
Run a whole folder of old photos through compression at once to reclaim disk space.
About Image Compressor
Most online image compressors work the same way: upload a file, wait for a server to process it, then download the result — and you only find out how much smaller it got after that whole round trip. This tool skips the guesswork by computing a live preview of the compressed file size for your first image the instant you touch the quality slider, using your browser's own image encoder — no server, no waiting, no upload.
Compression quality genuinely depends on the format. JPEG and WEBP are lossy formats with a real quality dial: dragging it down trades some visual detail for a meaningfully smaller file, which is exactly where most of the file-size savings on photos come from. PNG, on the other hand, is a lossless format — re-encoding it through a browser's canvas doesn't meaningfully shrink it, because there's no quality to trade away. Rather than pretend otherwise, this tool tells you exactly that when PNG is selected, and suggests switching to WEBP for real savings on images that don't strictly need to stay lossless.
For photos specifically, WEBP at a moderate quality setting typically produces the smallest file of the three formats for a given visual quality, which is why it's the default when the tool detects a photo-like image being compressed. JPEG remains a safe, universally-compatible choice when you need broad compatibility with older software or systems that don't recognize WEBP.
Batch mode compresses every image in your selection using the same format and quality setting, then bundles the results into a single ZIP file if you added more than one — so shrinking a whole folder of photos before uploading them elsewhere takes one action instead of one-by-one.
Image Compressor vs. other options
How Open Tools Library compares to desktop software and other online tools.
| Feature | Open Tools Library | Desktop software | Other online tools |
|---|---|---|---|
| Price | Free, unlimited | Often paid or subscription | Often free with daily limits |
| Installation | None | Required | None |
| File privacy | Never leaves your device | Stays local | Uploaded to a server |
| Result preview | Live, before you compress | Varies by app | Only after upload + processing |
| Speed | Instant, on-device | Fast | Depends on upload + server queue |
| Watermarks | Never | Never | Sometimes on free tiers |
Pro tips
- For photos, WEBP at 70-80% quality usually gives the best size-to-quality trade-off of the three formats.
- If you selected PNG and the live preview barely changes size, that's expected — switch to JPEG or WEBP for real compression on photographic content.
- Keep quality above 60% for images with fine text or detail; lower settings can introduce visible blocky artifacts.
- The live preview only computes for your first selected image — actual results for every image appear after you click Compress.
- PNG remains the right choice for screenshots or graphics with sharp edges and flat colors, even though it won't compress much further here.
Technical specs
- Supported input
- .jpg, .jpeg, .png, .webp, .gif, .bmp, and more
- Output formats
- JPEG, PNG, or WEBP
- Quality range
- 10% – 100%, adjustable in 5% steps
- Live preview
- Instant, computed for the first selected image
- Batch output
- ZIP file when compressing more than one image
- Processing location
- 100% local, in your browser
Privacy & security
Photos you're compressing to share or upload elsewhere shouldn't have to pass through yet another server first.
Each image is re-encoded locally — never uploaded, never seen by a server.
No account, no email, no login — just images in, compressed images out.
Nothing is retained after your download finishes; there's no copy waiting on a remote server.
Equally private whether you're compressing a single photo or a batch of hundreds.
Frequently asked questions
Is my image uploaded to a server?
No. Every image is re-encoded entirely in your browser — nothing is ever uploaded.
Which format compresses best?
For photos, WEBP typically gives the smallest file at a given visual quality, followed by JPEG. PNG is lossless and won't shrink much regardless of settings.
Can I compress multiple images at once?
Yes. Add as many images as you like and compress them all in one action — you'll get a ZIP file if you compressed more than one.
Will compressing reduce image dimensions?
No, only file size. Compression here changes encoding quality, not pixel dimensions — use Image Resizer if you also want to change dimensions.
Why does the live preview only show one image?
Computing a full preview for every image in a large batch on every slider movement would be slow — showing the first image gives you an instant, representative estimate instead.
Is there a limit on image size or count?
No hard limit — very large images or batches just take a little longer since everything processes on your device.
Troubleshooting
PNG output barely got smaller
This is expected — PNG is a lossless format, and a browser's PNG encoder doesn't have a quality dial to trade away detail for size the way JPEG and WEBP do. Switch the output format to JPEG or WEBP for meaningful compression on photos.
The compressed image looks blocky or smudged
The quality setting is too low for that image's content. Raise the quality slider, especially for images with text or fine detail.
The live preview isn't updating
It only recomputes for the first image in your selection and briefly debounces while you drag the slider — give it a moment after you stop moving it.
One image in my batch failed to compress
The file may be corrupted or in a format your browser can't decode. Try opening it in an image viewer first to confirm it's valid.
Related searches
Landed here looking for something worded a little differently? Image Compressor covers all of these too:
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