How to Compress Images Without Losing Visible Quality

What without losing quality really means

Strictly speaking, most compression that makes a meaningful difference to file size does discard some information. The practical goal is no visible loss: a file that looks the same to a person viewing it at its intended size, while being a fraction of the original weight. Getting there is mostly about three decisions made in the right order: the pixel size, the format and the quality setting.

Lossless compression, by contrast, keeps every pixel identical. It is the right choice for some images, such as screenshots and logos, but for camera photos it rarely saves much. Knowing which kind of image you have is the first step.

Resize first: the biggest saving

A modern phone photo can be several thousand pixels wide. If it will appear in a blog post, an email, a presentation or a form at a few hundred or a thousand pixels wide, all those extra pixels are wasted. Halving both the width and the height leaves only a quarter of the pixels, which usually shrinks the file dramatically before you touch any quality setting.

• Work out the display size. A full-width image on a typical web page, a thumbnail and a form photo all need very different sizes.
• Allow for sharp screens. For crisp display on high-density phone and laptop screens, many people use around twice the displayed width. Beyond that, extra pixels add bytes but little visible benefit.
• Crop away what you do not need. Empty sky or wall still costs bytes.
• Never enlarge to compress. Making an image bigger adds pixels without adding detail.

The Resize and crop tool handles single images. For a batch, the Batch image compressor can work through many files in one go.

Choosing JPEG, PNG, WebP or AVIF

For online application forms, use whatever the form asks for, which is usually JPEG. A beautifully compressed WebP is no use if the portal rejects it. Our guide on reducing a photo to 20 KB or 50 KB covers form uploads specifically.

For your own website or blog, WebP is a good everyday choice for photos, and AVIF is worth testing if your audience uses modern browsers. Keep a JPEG fallback in mind if you are not sure every visitor or platform supports the newer format.

For sharing on chat apps or email, JPEG is the safest bet, because every phone and computer opens it.

TipConverting between formats is easy with the Image format converter. iPhone HEIC photos need their own converter first; see converting HEIC to JPG.

When PNG is the right answer

PNG is often blamed for big files, but for the right kind of image it is the best choice. Screenshots, app interfaces, charts, diagrams, logos, scanned line drawings and anything with crisp text have large areas of flat colour and hard edges. Lossless PNG compression handles these efficiently, and the text stays perfectly sharp.

Save the same screenshot as a JPEG and you will often see faint smudges and ringing around letters, sometimes at a file size that is not even smaller. JPEG is designed for the smooth gradients of photographs, not hard edges.

• Use PNG for screenshots, logos, icons, diagrams and images that need transparency.
• Use JPEG or WebP for photographs, including photos of people, places and products.
• Mixed image? A photo with a small caption is still a photo. A screenshot of a web page that contains a small photo is still a screenshot.

If a PNG is still too large, reduce its pixel dimensions first. For website use, WebP can also store graphics losslessly or with transparency and is often smaller than PNG.

Picking a quality setting

Lossy formats such as JPEG and WebP have a quality slider, usually from 0 to 100. The relationship between the number and the file size is not linear: the top end of the scale adds a lot of bytes for detail you are unlikely to see, while the bottom end quickly introduces blocky patches and smeared textures. Most images look good somewhere in the middle to upper range, but the exact sweet spot depends on the picture.

1. Start with a moderate to high setting in the Batch image compressor.
2. Compare the result with the original at 100% zoom, looking at faces, fine hair, foliage, gradients in the sky and any text.
3. If you cannot see a difference, try a lower setting and compare again.
4. Stop at the lowest quality where the image still looks right to you.
5. If you need a specific file size, set the optional target KB per image and let the tool search the quality for you.

Watch outAvoid compressing the same JPEG repeatedly. Each lossy save throws away a little more detail, and artefacts build up. Keep your original and always compress from it.

For a single photo that must fit a strict KB limit for a form, the Photo and signature size optimizer combines crop, maximum dimensions and a target KB in one step.

Strip metadata for smaller, more private files

Camera photos carry EXIF metadata: the date and time, camera or phone model, settings and, if location was enabled, GPS coordinates. Some files also contain embedded thumbnails or colour profiles. This metadata usually makes up only a small part of a large photo, but on a heavily compressed small image it can be a noticeable share of the file. More importantly, location data can reveal where you live or work.

The EXIF and location cleaner removes this information in your browser. It is a good last step before posting images publicly or sending them to people you do not know.

Images inside PDFs

If your images end up in a PDF, for example scanned certificates or photos of documents, compressing the images before you build the PDF gives you the most control. Resize and compress them first, then combine them with Images to PDF. If the finished PDF is still too large, Compress PDF or our guide to compressing a PDF to 100 KB will help.

All of these tools run in your browser, so your images are processed on your own device. There is no upload, no sign-up and no watermark.