Large image files slow down websites, bounce off email size limits, and fill up storage. Reducing image size is one of the most useful skills for anyone who works with photos or graphics. Here's how to do it effectively.
Modern cameras and phones produce images at very high resolutions — a recent iPhone photo can be 10–20 MB. This is great for printing, but far more data than you need for screen display, email, or web use. A typical website image only needs to be 100–300 KB to look sharp on screen.
Lossy compression (used for JPG) discards some image data to achieve smaller sizes. At moderate quality settings (70–85%), the difference is invisible to the human eye, but file sizes drop by 60–80%.
Lossless compression (used for PNG) reduces file size without discarding any data — useful when you need pixel-perfect accuracy (logos, screenshots, graphics with text). The size reduction is more modest, typically 10–30%.
💡 Rule of thumb: Use JPG for photos, PNG for graphics, WebP for web. If in doubt, JPG at 80% quality is a safe default.
Processing happens entirely in your browser — your image is never uploaded to a server.
For web use, aim for images under 200 KB. A quality setting of 75–80% for JPG is usually indistinguishable from the original at screen resolution. Also resize the image to the actual dimensions it will display — a 4000×3000 photo displayed at 800×600 is carrying unnecessary data.