How to Compress Images Without Losing Quality
Quick answer
To compress an image without visible quality loss, first resize it to the largest size it will actually be displayed at, then save it as JPEG or WebP at a quality setting of about 75-85, or as lossless PNG/WebP if it is a graphic with sharp edges or transparency. This combination usually cuts file size by well over half while the result looks the same to the eye.
Key takeaways
- Resizing oversized photos to their real display size is the single biggest saving.
- JPEG or WebP quality 75-85 is a common sweet spot: much smaller files with no obvious artifacts.
- Lossless compression (PNG, lossless WebP) keeps every pixel but saves far less on photos.
- Re-saving a JPEG repeatedly adds new loss each time, so always compress from the original.
- Removing metadata trims a few extra kilobytes and protects your privacy.
Can you really compress an image without losing quality?
Yes, in two different senses: lossless compression keeps every pixel identical, while well-tuned lossy compression discards detail the eye cannot see, so the result is visually lossless even though it is not bit-for-bit identical.
Lossless formats such as PNG and lossless WebP are ideal for logos, screenshots and graphics with text, but they only shrink photos modestly. Lossy formats such as JPEG, WebP and AVIF are built for photographs and can reduce file size dramatically before any change becomes noticeable.
Step-by-step: compress an image the right way
The order of operations matters: change the dimensions first, then the format, then the quality setting.
- Start from the original, highest-quality file, not a copy that has already been compressed.
- Resize to the largest size the image will be shown at. For a blog column 800 px wide, 1600 px covers high-density (2x) screens; a 6000 px camera original is wasted bandwidth.
- Choose the format: JPEG or WebP for photos, PNG or lossless WebP for graphics, screenshots and anything that needs transparency.
- Set quality to around 80, compare the preview with the original at 100% zoom, and lower it in small steps until you see artifacts, then step back up.
- Strip metadata (camera data, GPS) if the image is going on the web.
- Save the result under a new name so the original stays untouched.
What quality setting should I use?
For most photos, a JPEG or WebP quality of 75-85 gives the best balance between size and appearance; going above 90 makes files much larger for very little visible gain.
Quality numbers are not comparable between encoders or formats, so WebP 75 and JPEG 75 do not mean exactly the same thing. Judge by eye: look at smooth gradients like sky and skin, and at sharp edges such as text, where blocking and halos appear first. Images with fine text or line art usually need a higher setting or a lossless format.
Which format compresses best?
For photos on the web, WebP and AVIF usually beat JPEG at the same visual quality; according to Google's WebP compression study, lossy WebP files were about 25-34% smaller than comparable JPEGs.
AVIF often compresses further still, but it encodes more slowly and older software may not open it. JPEG remains the safest choice when you do not know where the file will end up, such as email attachments or upload forms that only accept JPG. For a deeper comparison, see the JPG vs PNG vs WebP guide.
Mistakes that quietly ruin image quality
Most visible quality loss comes from a handful of avoidable habits rather than from compression itself.
- Re-compressing a JPEG that was already compressed, which stacks artifacts each time (generation loss).
- Saving photos as PNG, which produces huge files with no quality benefit.
- Saving logos or screenshots as low-quality JPEG, which smears text and flat colors.
- Upscaling a small image to make it look sharper; it only adds pixels, not detail.
- Letting a website or app compress the image again after you already did, so it is compressed twice.
How to compress images for free in your browser
imgloom's Compress Image tool lets you adjust a quality slider for JPG, WebP or AVIF and see the new file size before you download, and everything runs on your own device, so your images are never uploaded to a server.
If you need to hit an exact limit, such as under 200 KB for a form, the Compress to Size tool searches for the highest quality that fits your KB target. Pair either with Resize Image when the original dimensions are far larger than you need. The tools are free, need no sign-up, and work in any modern browser on desktop or phone.
Frequently asked questions
- Does compressing an image reduce its resolution?
- Not necessarily. Compression changes how the pixels are stored, while resolution only changes if you also resize the image. You can keep the same dimensions and still shrink the file by lowering quality or switching format.
- What is the best quality setting for JPEG?
- A quality of 75-85 is a widely used sweet spot for photos. Go higher for images with fine text or for print, and lower only if you have checked the result at full size.
- Is PNG better quality than JPG?
- PNG is lossless, so it never adds compression artifacts, but for photos a high-quality JPG looks the same at a fraction of the size. PNG is the better choice for graphics, screenshots and images that need transparency.
- Why does my image look worse after compressing it several times?
- Each lossy save throws away a little more detail and adds new artifacts. Always compress from the original file rather than from an already-compressed copy.
- Is it safe to compress private photos online?
- It depends on the tool. Many online compressors upload your file to a server; browser-based tools such as imgloom process the image on your own device, so the file never leaves it.