How to optimize and resize images for your website
The exact process I use — no extra apps, no learning curve, just what's already on your Mac.
Images make up over 51% of the average website's total bandwidth, more than any other single resource on a page. That's the kind of stat that sends people straight to Google looking for a fix. Skip that step — your Mac already has what you need.
Why you don't need extra compression apps
I get asked a lot which app I use to compress photos before they go on a website. People expect a name they've never heard of, some clever plugin, a paid subscription. But I use Preview. :)
I've tried multiple tools and apps, but most add a step without adding real value, and a few just repackage what your Mac can already do on its own. For a task this simple, the built-in option wins.
Here's exactly what I do every time I upload a new photo to my site and my clients'.
Optimize your photos the simple way
The process takes less time than it takes to explain it, and once you've done it a couple of times, it becomes automatic.
Open your image in Preview
Double-click any image on your Mac and it opens in Preview by default.
Resize your image
Once the image is open, Preview lets you adjust width, height, and file size directly through its built-in size tool. Go to Tools > Adjust Size… I keep the default resolution and scale it down using percent until the file lands well under 500 KB, which is comfortably fast for almost any site (the closer to 250 KB, the better).
Then, I also crop them if necessary, and I feel like I beat the system by reducing the image size even more. 🤓
Skip PNG unless you need transparency
PNG has its place, but it's not for regular photos. PNG is a format built for graphics and transparency, while JPEG is built for photos and compresses them far smaller with almost no visible difference. Save your PNGs for logos. Export everything else as JPEG.
Check the file size before you upload
Before I upload images into sites, I view them as List, and check all file sizes one more time. If it's still sitting north of a MB, I go back and resize it again. It only takes a second, and it saves me from ever wondering later why a page feels heavy.
Four small habits, and none of them require anything you don't already have. But the reason this matters goes past just having a faster site.
What optimizing images does for your site
Google's own research on image performance points at the same thing over and over: the biggest single win for site speed usually comes from properly sized images, not a redesign or a platform switch. That lines up with what I see on client sites constantly. The fix is almost always this.
There's an SEO upside here too. Images are often the biggest single contributor to a page's overall size, and a slow page works against you in search just as much as it works against you with visitors. Optimize your images, and you're not just making the site feel faster. You're doing real work toward how well it ranks. You go SEO girl!
There's a compounding effect too. Every photo you resize before uploading is one less thing dragging down every page it lives on, and that adds up fast on a site with a gallery, a shop, or a blog that grows every month. A habit that takes 30 seconds per photo now saves you a much bigger cleanup job later.
I build this step into every site I hand off, and it's one of the easiest wins a business owner can take on themselves. No new software, no learning curve, no subscription. Just an app that's already sitting in your dock.
