Compress Your Images Before Uploading Them to Your Website

The single biggest reason websites load slowly is oversized images. I see it constantly: a 4MB photo file displayed at 800 pixels wide on a page that takes eight seconds to load. Your visitors won’t wait that long. Neither will Google.

The difference between size and dimensions

This trips people up. An image has two kinds of “size”: its pixel dimensions (3000 x 2000) and its file weight (4.2 MB). You need to address both, but they’re separate problems.

Dimensions should match how the image will be displayed. If your layout shows an image at 1200 pixels wide, there’s no reason to upload a 6000-pixel original. Serve what you need. (WordPress handles this automatically — more on that below.)

File weight depends on compression. A 1200-pixel-wide JPEG can be 2 MB or 200 KB depending on how it’s compressed. The visual difference between the two is usually invisible. The speed difference is not.

How to compress

Before uploading, run your images through a compression tool. My go-to is Squoosh — it’s free, runs in your browser, and lets you compare before and after side by side. For batch processing, ImageOptim (Mac) or ShortPixel work well.

For JPEGs, a quality setting of 80-85% is usually the sweet spot — significant file savings with no visible loss. For PNG files, the savings come from reducing unnecessary metadata and optimizing the compression algorithm.

Modern formats

WebP and AVIF are newer image formats that produce smaller files at the same visual quality as JPEG. Most browsers now support them. If your CMS or hosting setup can serve these formats automatically, use them. If not, a well-compressed JPEG is still perfectly fine.

Don’t skip this

A fast website ranks higher, converts more visitors, and feels more professional. 3 Millimeters is a media-rich storytelling site I built with video, audio, and large photographs — it loads fast because every image is properly compressed and served in modern formats. Image compression is the single easiest thing you can do to speed up your site. It takes a minute per batch and the impact is immediate.