How to compress a JPEG
- Add your images. Drag and drop your JPG files onto the dropzone, click to browse, or paste from your clipboard. You can add several at once.
- Choose a quality level. Use the quality slider or a preset. Around 75 is a great balance of size and visual quality for most photos.
- Let it compress on your device. Each image is compressed locally with MozJPEG. You'll see the original size, new size, and percentage saved for every file.
- Download your files. Download images one by one, or grab everything at once as a ZIP. Adjust the quality and re-compress anytime.
Why compress JPEG images?
JPEG (also written JPG) is the most common format for photographs on the web, but camera and phone images are often far larger than they need to be — frequently several megabytes each. Large images slow down websites, fill up email attachments, eat into cloud storage, and waste mobile data. Compressing them keeps the visual quality you care about while dramatically cutting the file size, often by 60–80%.
Because this tool runs entirely on your device, it is also the private way to do it. Traditional online compressors upload your photos to a remote server, process them there, and send them back. Here, your images are read into memory, compressed with a WebAssembly build of MozJPEG, and handed straight back to you — they never touch a network.
Lossy compression and quality: what to expect
JPEG is a lossyformat: to make files smaller it permanently discards image detail that the human eye is least likely to notice. The quality slider controls how aggressive that is. Higher values preserve more detail and produce larger files; lower values save more space but can introduce visible “artifacts” such as blockiness or halos around sharp edges.
For most photographs, a quality of 70–80 is the sweet spot — the result is visually indistinguishable from the original at normal viewing sizes, yet a fraction of the size. Drop to 50–60 when small size matters more than perfect fidelity (for example thumbnails), and stay at 85–90 for images with fine gradients or text where artifacts are more obvious. Compression is cumulative, so always re-compress from your highest quality original rather than from an already-compressed copy.
What is a JPEG, and when should you use it?
JPEG was standardized by the Joint Photographic Experts Group and uses the discrete cosine transform to compress continuous-tone images efficiently. It excels at photographs and realistic imagery with smooth color transitions, which is why nearly every camera saves JPEGs by default. You can read the technical details on MDN’s image format reference.
JPEG is not always the right choice, though. It does not support transparency and handles flat graphics, logos, screenshots, and text poorly — those compress better and look sharper as PNG. And for the smallest possible photos with modern browser support, newer formats win: a WebP file is typically 25–35% smaller than an equivalent JPEG, and AVIFcan be smaller still. If you’re optimizing for the web, try converting with our image converter and compare.
Tips for the best results
- Start from the original. Re-saving a JPEG repeatedly degrades it. Keep a master copy and compress from that.
- Resize before you compress.If an image will be displayed at 1200px wide, there’s no need to ship a 6000px file. Use the built-in resize option for a much bigger saving than quality alone.
- Use presets to compare.Try “Balanced” first, then re-compress at “Smallest” and check whether you can tell the difference at your display size.
- Batch similar images together. Photos from the same camera usually look great at the same quality setting, so you can process them in one go.