About Image Compressor
This image compressor makes a picture file smaller by re-encoding it as JPEG or WebP at a quality you set between 5 and 95 percent. The default is 70 percent JPEG. The pixel dimensions stay exactly the same; only the amount of detail kept per pixel changes. After each run the Details panel shows the new file size, the original size and how much was saved, as a size and as a percentage, so you can move the slider until the trade looks right. Compression is lossy, and it happens in your browser, so the file is not sent to a server.
JPEG and WebP quality settings: what to expect at each level
The slider maps directly to the encoder quality your browser uses. Results vary by picture, so treat this as a starting point and check the preview.
| Quality | Typical look | Good for |
|---|---|---|
| 90 to 95 | Visually the same as the source for most photos; modest saving | Images that will be edited again, print files, product close-ups |
| 80 to 85 | Differences only visible when zoomed in and compared side by side | Portfolio and hero images, photos with fine texture |
| 70 to 75 | Clean at normal viewing size; the tool's default range | General web photos, blog images, email attachments |
| 55 to 65 | Slight softness; faint halos around sharp edges | Thumbnails, listing photos, previews |
| 40 to 50 | Visible blocks in skies and gradients, fuzzy text | Small previews where size matters more than looks |
| 5 to 35 | Heavy blocking and colour banding | Placeholders and tests only |
No file sizes are quoted here because they depend entirely on the image: a busy, detailed photo keeps more data at any setting than a plain one.
What happens to each file type when you compress it
| Source file | Output as JPEG | Output as WebP |
|---|---|---|
| JPEG photo | Re-encoded at the chosen quality; smaller if the setting is below the original's | Re-encoded as WebP, usually smaller again |
| PNG photo or screenshot | Converted to lossy JPEG, often a very large saving for photos | Converted to lossy WebP |
| PNG with transparency | Transparent areas are filled with white | Transparency is kept |
| WebP | Converted to JPEG; may grow if the source was heavily compressed | Re-encoded at the chosen quality |
| Animated GIF | First frame only, as a still image | First frame only, as a still image |
There is no PNG output. A file that must stay lossless needs a dedicated PNG optimiser instead. WebP output relies on the browser's own encoder: a browser that cannot write WebP produces a PNG instead, usually larger than the source, so check the Format line in the Details panel.
How to get an image under a size limit
Upload forms and email often set a ceiling such as 100 KB, 500 KB or 2 MB. Work through these in order and stop when File size is below the limit.
- Compress at 70 percent JPEG and read File size.
- If the form accepts WebP, switch Output format to WebP at the same quality and compare.
- Step the quality down by 5 at a time to about 50, checking the preview each time.
- Still too large? Reduce the pixel dimensions with the Image Resizer, for example to 1600 pixels on the long side, then compress the resized copy.
- For a strict limit on a document scan or ID photo, crop away empty margins before resizing. Fewer pixels always means fewer bytes.
Why a PNG barely shrinks until you change its format
PNG is lossless. It stores every pixel exactly, and its size depends on how repetitive the picture is, not on a quality setting. A screenshot with large flat areas is small as a PNG. A photograph has almost no repetition, so the same photo saved as PNG is often several times the size of a good JPEG.
That is why this tool always writes JPEG or WebP. For a photo that arrived as a PNG, switching format does most of the work before the slider is touched. For a logo, chart or screenshot with sharp text, the trade is worse: lossy encoding puts faint halos around hard edges, and the saving is smaller. Check the preview at full size before replacing a crisp PNG with a JPEG.
Re-encoding also drops the embedded metadata, such as camera model, capture time and GPS position, because only the pixels are redrawn. That saves a little space and removes location data from photos you plan to share.
Reading the Details panel after a run
The Saved line is the original size minus the new size, with the percentage rounded to a whole number.
A photo that shrinks
Original size 4.00 MB, new File size 1.00 MB
Saved shows 3.00 MB (75%). Dimensions are unchanged and Format shows JPEG or WebP.
A file that was already small
A JPEG saved at low quality, re-encoded at Quality 90
The new file is larger than the source, so Saved shows 0 B with the hint that the original is already smaller than the recompressed version.
Keep the original in this case, or lower the slider.
A transparent PNG logo
Output format JPEG
The logo appears on a white background, because JPEG cannot store transparency. Choose WebP to keep the transparent areas.
Step by step
- 1
Under Image, choose a JPEG, PNG, WebP or other picture file up to 30 MB.
- 2
Set Output format to JPEG (best compression) or WebP (smaller, modern browsers).
- 3
Move the Quality slider. It runs from 5 to 95 percent in steps of 5 and starts at 70.
- 4
Read File size, Original size and Saved in the Details panel, and look closely at the preview around edges and text.
- 5
Download the result. It is saved as the original name with -compressed added, ending in .jpg or .webp.