What Is a Good Image File Size for Squarespace? (The 250 KB Rule Explained)

You have probably seen this number before

Search for Squarespace image size advice and 250 KB comes up constantly. Squarespace's own help documentation recommends keeping images under 500 KB. Many SEO experts say 250 KB for most images, 500 KB for banners.

But where does 250 KB come from? And what actually happens if your images are larger than that?

Where the 250 KB number comes from

250 KB is not an arbitrary number. It is based on two things: what produces acceptable visual quality at typical web display sizes, and what Google's Core Web Vitals thresholds require to achieve a good Largest Contentful Paint score.

At 250 KB, a 1,500-pixel-wide image looks sharp on both standard and retina screens. At 2 MB, the same image looks identical on screen but takes 8 times longer to load. The extra file size is data that screens cannot display, it is wasted bytes.

Google's LCP threshold for a "good" score is under 2.5 seconds. On a standard mobile connection, a single 2 MB image can push LCP above that threshold on its own. A 250 KB image typically does not.

What happens above 250 KB

Above 250 KB, each additional megabyte of image data costs you:

• Load time on mobile - typically 0.5 to 2 seconds per megabyte on a standard 4G connection
• LCP score - the more image data, the worse your Largest Contentful Paint
• Bounce rate - every extra second of load time increases the percentage of visitors who leave before the page finishes loading
• Google rankings - page speed is a confirmed ranking signal

A site with 100 images averaging 2 MB each has 200 MB of total image weight. At 250 KB per image, that drops to 25 MB. Pages that took 5 seconds to load start loading in under 2 seconds.

Does Squarespace not handle this automatically?

Squarespace resizes images to multiple widths and serves them through a CDN. It does not aggressively compress your original file. If you upload a 5 MB image, Squarespace serves a smaller dimension version but that version is still derived from a 5 MB source. It will be larger than it would be if you had started with a properly compressed file.

The platform also applies some automatic compression, but not enough to bring a 5 MB phone photo down to 250 KB. You need to do that step yourself.

How to get every image on your site to 250 KB

For images you have not yet uploaded: run them through TinyPNG or Squoosh before uploading. Aim for 250 KB or below.

For images already on your live Squarespace site: re-uploading them one by one is time-consuming. SquareOptimizer is a browser extension that compresses all existing images on your site in one session, directly inside your editor. It targets 250 KB automatically without any manual intervention.

Scan your site for free and compress Squarespace images to 250 KB across your entire site in one click.