Image Compressor

Why compress images before you upload them

Photographs from phones are often several megabytes. That is more than a web page, an email, or a CMS upload limit needs. Compression reduces those bytes by discarding detail the eye is unlikely to notice — typically by encoding as JPEG or WebP at a chosen quality, and by shrinking the longest side so a 4000-pixel photo is not served at 4000 pixels on a 1200-pixel article.

JPEG and WebP are lossy: each pass throws some information away. PNG is lossless and keeps sharp edges and transparency, but it rarely beats JPEG on photos. WebP usually wins on size at a given visual quality in current browsers. This tool never upscales; the max-edge setting only shrinks images that are larger than the cap.

Animated GIFs become a single frame because the Canvas API draws one bitmap. SVG is rasterised. If you need the original vector, keep the SVG. All of this runs in your browser — the file is not uploaded.

A practical workflow: cap the long edge at 1920 for web articles, 1200 for social posts, and use JPEG quality around 70–80 or WebP around 75. Compare the before/after sizes on this page before you download.

Do not compress a file that is already a tiny PNG icon, and do not re-compress a JPEG many times — each pass adds artefacts. Start from the original when you can.

Two ways the file gets smaller

The compressor combines two independent savings. The longest-edge limit (1920 pixels by default) scales large photos down without ever enlarging small ones — a 4000×3000 phone photo becomes 1920×1440, less than a quarter of the pixels. The quality setting (75% by default) then controls how aggressively JPEG or WebP encode those pixels. Reducing dimensions usually saves more than lowering quality.

If a combination of settings would produce a file that is not smaller than the original — common for images that were already optimised — the tool warns you, so you can keep the original instead.

Settings for common jobs

• Website photos: longest edge 1600–2000 px, JPEG quality 70–80 or WebP 70–75.
• Email attachments: longest edge 1280–1600 px and quality around 70 keeps a photo well under 1 MB.
• Upload forms with a size cap (often 1–2 MB): start at 1920 px and quality 75, then lower the edge before the quality.
• Screenshots and diagrams with text: use PNG, or WebP at high quality — JPEG blurs sharp text edges.

Why lower quality is not always smaller

File size depends on image content as much as on settings. Smooth skies and blurred backgrounds compress very well; grass, gravel, fabric and camera noise do not. A screenshot saved as JPEG can come out larger than the original PNG, because flat colours and sharp edges are exactly what PNG is good at. Compare the before and after figures and the preview rather than relying on the slider alone.

Checking the result

Look at the preview at full size on the areas compression damages first: faces and skin, which turn waxy; blue skies, which show banding; and edges of text or logos, which grow halos. If any of those look wrong, raise the quality a step or use WebP, which degrades more gracefully than JPEG at low settings.