How the image compressor makes files smaller
Each format is squeezed in the way that suits it. A JPG or WebP photo is encoded again at a lower quality setting. Both formats store a picture as small blocks of detail and drop the finest variations the eye barely notices; a lower setting drops more of them, so the file shrinks while the picture looks almost the same at normal viewing size.
PNG is lossless, so a quality setting does nothing for it. Instead the image compressor reduces the picture to a palette of at most 256 colors, a technique called color quantization, and stores every pixel as one number pointing into that palette. In our tests a PNG screenshot shrank by 67 percent and a PNG photo by 60 percent at 256 colors, and transparent areas stay transparent.
Compress by quality or to a target file size
Quality mode applies the same settings to every file. The default of 75 percent for JPG and WebP is a good balance for screens, and 256 colors is the safe choice for PNG. Lower either one for smaller files, or pick All colors to recompress a PNG without changing a single pixel.
Target size mode is for limits you have to meet. Enter a number such as 100 KB and the image compressor looks for the highest quality that still fits under it. If even a modest quality is too large, it scales the picture down step by step until it fits, and the result line shows the new dimensions. Sizes are counted in thousands of bytes, so a file under 100 KB passes forms that count 1,000 bytes per kilobyte as well as those that count 1,024.
Choosing settings for photos, graphics and screenshots
For photos you might print or edit later, stay between 85 and 92 percent. For images on a website or in a presentation, 70 to 80 percent usually looks identical on screen at a fraction of the size. Thumbnails and previews can go down to about 60 percent before blocky edges appear around fine detail.
Screenshots, charts, logos and illustrations with flat colors compress best as PNG with a reduced palette, and many look perfect at 128 or even 64 colors. Keep photos in JPG or WebP, because a photo saved as PNG stays large even after quantization. Pixel art and images where every exact color matters should use All colors.
Meeting size limits on upload forms
Job portals, exam registrations, visa applications and government forms often cap photos and signatures at 20 KB, 50 KB or 100 KB, while a phone camera produces files of several megabytes. Switch the image compressor to Target file size, click the limit you need, and download the result.
Many of those forms also ask for a particular format or pixel size, so read the instructions first. If they want a JPG, set Save as to JPG. When a file is far larger than the limit, its dimensions are reduced as well as its quality, which is usually what such forms expect; check the new width and height in the list before you submit.
Compressing images for websites and page speed
Images often make up most of the weight of a web page, and large ones delay the moment the main content appears. Compressing every picture before it goes into a CMS or an online shop keeps pages fast on mobile connections and saves storage on your hosting plan.
For photos on the web, WebP at 75 percent is a strong default, since every current browser displays it. Keep a copy of the original as well: if you later need a bigger or sharper version, you can start again from the full-quality file instead of compressing a copy that was already compressed.
Email, messaging and cloud storage
Personal Gmail accounts accept 25 MB of attachments per message, and anything larger is turned into a Google Drive link. A handful of camera photos can pass that limit, while the same photos compressed to around 500 KB each fit easily and open faster for the person receiving them.
Messaging apps shrink photos themselves before sending, so there a compressor mostly saves mobile data and upload time. For pictures shared through cloud folders, smaller files sync faster and use less of your storage quota.
Why a compressed image can come out larger
Some files are already optimized. A JPG saved at a low quality, a PNG with only a few colors, or a picture that has been through another compressor may not get any smaller, and encoding it again could even add bytes. When that happens the image compressor keeps your original file untouched and says so in the list, so you never download something heavier.
Changing format can also add bytes. A screenshot turned from PNG into JPG, or a small graphic turned into WebP, may grow because the new format suits that picture less well. In that case set Save as back to Same format.
Privacy, metadata and the before-and-after view
Everything happens in your browser: files are read, compressed and saved on your own device, so private screenshots and client work never reach a server. Compressed copies are written without EXIF data, which removes camera details and GPS location. Originals that are kept untouched still carry their metadata.
Press Compare on any result and drag the divider across the original and the compressed version. Look at fine textures, text edges and smooth skies, where compression shows first, and raise the quality if you see blocks or bands.