Every photo from a modern phone is several megabytes, and a page full of them loads slowly, costs mobile data and frustrates visitors. Compression solves this by removing data the eye barely notices, and done well it can cut a file to a tenth of its size with no visible difference. The key is choosing the right method for the image in front of you, because a photo, a logo and a screenshot all compress differently. This guide covers the three steps that matter most, choosing the right format, resizing to the size you actually need, and applying compression at a sensible quality setting.

Start With the Right Format

Format choice does more work than any compression slider. Use JPEG for photographs, because it is designed for the smooth gradients and colours of real images. Use PNG only when you need transparency or crisp text, such as a logo, because PNG files are much larger for photos. For the web, consider WebP, which typically produces files noticeably smaller than JPEG at the same visible quality and is now supported by all major browsers.

If your site or tool supports it, serve WebP with a JPEG fallback so older devices still see the image. Avoid saving screenshots as JPEG, because the compression smudges sharp text edges; PNG or WebP suits them better. Getting the format right first means the compression step has far less work to do, and your final file will be smaller at the same quality.

Resize Before You Compress

Most images are far larger than they need to be. A photo displayed at 800 pixels wide does not need to be stored at 4000 pixels wide, and resizing it first can cut the file size by more than half before compression even starts. Check the display size on your page, resize the image to roughly that width, and only then apply compression. There is no benefit in keeping pixels nobody will ever see.

Use a proper image editor or a batch resizing tool rather than relying on the browser to shrink a huge file, because the browser still downloads the full file. For a blog or shop, a good rule is to keep the longest edge under 1600 pixels for full-width images and under 800 pixels for thumbnails. Resize once, at the start, and every later step becomes faster and more effective.

Use Lossy Compression Wisely

Lossy compression is where the real savings happen. A quality setting around 70 to 80 percent usually looks identical to the original on screen while removing a large share of the file size, and dropping to 60 percent is often still fine for web photos. Work from a copy of the original, never the only copy, so you can always re-export if you go too far. Compare the compressed version side by side with the original at full zoom before you publish it.

Online compressors are convenient for one-off images, while desktop tools and batch scripts suit a whole folder. Whichever you use, aim for a target file size rather than a fixed quality number: under 200 kilobytes for a typical web photo is a sensible goal, and under 100 kilobytes is even better for thumbnails. If an image still looks sharp at that size, you have compressed it well; if it looks blocky or washed out, raise the quality slightly and try again.

Compressing images is a three-step habit: pick the right format, resize to the display size, then apply sensible lossy compression. Follow that order and your pages will load faster, your storage will last longer, and nobody will notice a difference in how your images look. Once you have done it a few times, the whole process takes less than a minute per image, and the faster loading times will be noticeable to everyone who visits your site.