If your website feels slow, there is a good chance images are the reason. A single photo straight from a phone camera can be 3 to 5 MB, while a well optimised web image of the same scene is often under 150 KB. That difference decides whether a page appears in one second or five, especially on mobile data.
Why image size matters
- Visitors leave slow pages. Many people give up if a page takes more than a few seconds to show content.
- Speed affects SEO. Google's Core Web Vitals, especially Largest Contentful Paint, are often held back by a large hero image.
- Mobile users pay for data. Smaller images make your site friendlier for people on limited plans.
Step 1: resize before you compress
There is no point sending a 4000 pixel wide photo to a phone with a 400 pixel wide screen. For most websites, 1200 to 1600 pixels wide is plenty for full width images, and 800 pixels is enough for images inside an article. Use the Max width option in our Image Compressor or the Image Resizer to get the right dimensions.
Step 2: choose the right format
- WebP gives the smallest files for both photos and graphics, and every modern browser supports it.
- JPG is a safe choice for photos when you need maximum compatibility.
- PNG is best for logos, icons and screenshots with sharp edges or transparency.
Switching an existing PNG photo to WebP often cuts its size by 70 to 90 percent. You can convert in bulk with our WebP Converter.
Step 3: pick a sensible quality level
Quality between 70 and 80 percent is the sweet spot for most photos. Most people cannot tell the difference on screen, but the file is a fraction of the size. Go higher for images with fine text, and lower for small thumbnails.
Our Image Compressor runs entirely in your browser, so your photos are never uploaded. Drop in a whole folder, check the savings, and download everything as a single ZIP.
Step 4: let the browser help
- Add loading="lazy" to images further down the page so they load only when needed.
- Always set width and height attributes so the layout does not jump while images load.
- Serve images through a CDN if your site has visitors from many countries.
Measure the results
After optimising, run your page through our Page Speed Checker to confirm the page weight has dropped, then keep an eye on Core Web Vitals in Google Search Console. Image optimisation is one of the quickest and cheapest speed wins you can get.