Images are usually the heaviest part of a web page. A single unedited photo from a modern phone camera can be several megabytes, and a page with a handful of such images can take seconds to load on a mobile connection. Visitors leave slow pages, and search engines treat loading speed as a ranking factor, so oversized images cost you twice: lost readers and lost visibility.

The good news is that most images carry far more data than the screen ever shows. A photo displayed at 800 pixels wide does not need to be stored at 4000 pixels wide, and the human eye cannot distinguish fine compression differences at normal viewing sizes. Reducing image file size is therefore mostly about removing data nobody will miss, not about accepting visibly worse pictures.

Before touching any compression setting, resize the image to the largest size at which it will actually be displayed. If your blog layout shows images at 1200 pixels wide, there is no benefit in uploading a 4000-pixel original. Resizing alone often cuts the file size by more than half, and it is a lossless step in the sense that you are simply discarding pixels the layout never uses.

Keep the original file archived separately so you can re-export at a different size later. For responsive sites, export two or three sizes and let the browser pick with the srcset attribute, so phones download the small version instead of the desktop-sized file. This single habit fixes the most common image-size problem on the web.

Format choice matters as much as compression. JPEG is the right choice for photographs, because it compresses smooth color gradients efficiently. PNG is better for graphics with sharp edges, text, and transparency, but it produces much larger files for photos, so never upload a photographic PNG to a web page. WebP, supported by all modern browsers, typically delivers the same visual quality as JPEG at a noticeably smaller file size, and AVIF goes further still where browser support allows.

A practical approach is to serve WebP with a JPEG fallback, or simply to export everything as WebP if your platform handles it. Converting a photographic PNG to JPEG or WebP is often the biggest single win available, and it requires nothing more than a free converter.

For JPEG and WebP, a quality setting between 75 and 85 percent is the sweet spot for web use. At this range, a typical camera photo shrinks dramatically while looking identical to the original at normal viewing distance. Below 70 percent, blocky artifacts start to appear in skies, skin tones, and flat color areas, and above 90 percent the file size grows quickly for almost no visible gain.

Two more free wins are worth applying to every image. First, strip EXIF metadata — camera model, GPS location, and shooting settings — which can add tens of kilobytes with zero visual value and also removes location data you may not want to publish. Second, for PNG graphics, run a lossless optimizer, which recompresses the file without changing a single pixel and typically saves a useful percentage.

Put it together into a checklist you can run in under a minute per image: resize to the display width, pick JPEG for photos or PNG for graphics, export at 75 to 85 percent quality, strip metadata, and convert to WebP when your platform supports it. Free tools like Squoosh, TinyPNG, and ImageOptim handle all of this in the browser or on the desktop, and most content management systems offer plugins that automate the whole pipeline on upload.

Finally, measure the result. Open your page, check the total image weight in your browser's developer tools, and compare before and after. When a page drops from several megabytes of images to a few hundred kilobytes with no visible difference, you have done the job properly, and both your visitors and your search rankings will reflect it.