Whenever you convert to JPG or WebP, you meet the quality slider. It runs from 1 to 100, and it is tempting to drag it to the top "just to be safe" or leave it wherever it happens to be. Neither approach is ideal. This guide explains what the number actually controls, recommends values for common situations, and gives you a quick test so you never have to guess again.
What the number really means
The quality value is not a percentage of quality. A JPG at 50 is not "half as good" as one at 100. The number controls how aggressively the encoder simplifies the picture. Lower numbers discard more fine detail and produce smaller files; higher numbers keep more detail and produce larger files.
Different programs use the scale differently, so "quality 80" in one app may not look exactly like "quality 80" in another. That is another reason to test with your own images rather than relying on numbers alone.
Why higher is not always better
The relationship between quality and file size is not a straight line. Near the top of the scale, file size climbs steeply while visible improvement almost disappears.
Roughly speaking, for a typical photo:
- Going from 70 to 85 increases file size noticeably and gives a visible improvement in fine detail.
- Going from 85 to 95 increases file size a lot, with an improvement most people cannot see at normal size.
- Going from 95 to 100 can nearly double the file size for practically no visible benefit.
That is why our converters default to around 85 for JPG and around 80 for WebP.
Recommended values
Photos for sharing, email and messaging: 80 to 85
Most messaging apps and social platforms re-compress images anyway, so very high quality is wasted.
Website photos: 75 to 85
Combine this with resizing to the display size. Visitors cannot tell the difference, and pages load faster.
Printing: 90 to 95
Prints are viewed up close and can reveal artefacts. Use a higher setting, and start from the highest-quality original.
Thumbnails and previews: 65 to 75
Small images hide compression artefacts well, so you can save more space.
Archiving: use a lossless format
For originals you want to keep forever, do not rely on any lossy quality setting. Keep the original file or a lossless PNG or TIFF copy.
What artefacts look like
Knowing what to look for helps you judge quality quickly.
- Blockiness: square patches in smooth areas such as skies and walls, typical of low-quality JPG.
- Ringing or halos: faint ripples around sharp edges and text.
- Colour smearing: colours bleeding slightly beyond edges, especially around red and blue objects.
- Blur and loss of texture: fine details such as hair, grass or fabric becoming smooth and plastic-looking.
- Banding: smooth gradients breaking into visible steps.
If you do not see any of these at the size your image will be viewed, your quality setting is high enough.
Lossless settings are different
Some formats offer a lossless option instead of, or as well as, a quality slider. Lossless WebP and PNG do not have a quality trade-off: every pixel is kept. Use them for screenshots, logos, text and diagrams. For photographs, lossless files are much larger, and the quality slider is usually the better approach.
A five-minute test to find your sweet spot
- Pick three typical images: a portrait, a landscape with sky, and something with fine detail or text.
- Convert each at 95, 85 and 70.
- View them at the size they will actually be used, on the device your audience uses.
- Note the lowest setting where you cannot see a difference.
- Use that value for similar images from now on.
Most people discover that 80 to 85 is indistinguishable from 95 for everyday photos, and that 70 is fine for small thumbnails.
Special cases
Images with text
Screenshots, slides and infographics show artefacts around letters at moderate quality. Use lossless WebP or PNG, or raise JPG quality to 90 and above.
Images converted from already-compressed sources
If your source is already a JPG, WebP or AVIF, it has been compressed once. Re-compressing at a high setting mostly preserves the existing artefacts and inflates the file. A setting around 85 is usually plenty.
Images with large smooth areas
Skies, studio backgrounds and gradients reveal banding and blockiness first. Check those areas specifically.
A worked example: hitting an upload size limit
A job portal requires a profile photo under 500 KB. Your photo is a 4 MB JPG. The tempting move is to drop quality to 30, which makes the face blotchy. A better approach:
- Resize the photo first. The portal shows profile pictures at a few hundred pixels wide, so 800 pixels is plenty.
- Convert at quality 85.
- Check the size. In most cases the photo is now far under the limit and still looks crisp.
Reducing dimensions to what is actually displayed almost always beats lowering quality aggressively.
How quality relates to resizing
Resizing and quality work together. Resizing removes pixels you do not need; quality controls how carefully the remaining pixels are stored. If you must save space, remove pixels first. A smaller image at quality 85 nearly always looks better than a large image at quality 40, even when both files are the same size.
Common mistakes
- Always choosing 100. Huge files, no visible gain.
- Choosing very low values to hit a size limit when resizing would be better. Reducing dimensions often saves more space with less visible harm.
- Judging quality zoomed in at 400 percent. Nobody views images that way. Judge at real size.
- Repeatedly re-saving lossy files. Each save loses a little more. Edit in a lossless format and export once.
Questions people ask
Is 85 good enough for professional work? For screen use, yes. For print, consider 90 to 95.
Why do two images at the same quality have different file sizes? File size depends on content. Detailed, noisy images need more data than simple, smooth ones.
Does quality affect image dimensions? No. Quality only controls compression; dimensions stay the same unless you resize.
In short
The quality slider controls how much detail is discarded, not a percentage of goodness. Use around 85 for everyday photos, 75 to 85 for the web, 90 to 95 for print, lower for thumbnails, and lossless for text and graphics. Run a quick test with your own images once, and you will never need to guess again.