Why PNG hurts page speed
Google measures how fast your page loads — especially Largest Contentful Paint (LCP), which is often a hero image or banner. If that image is a 3 MB PNG photo, visitors on mobile wait longer, bounce rates rise, and your SEO score drops.
JPG compresses photos efficiently. A 3 MB PNG photo might become 200–400 KB as JPG with little visible difference on screen.
PNG vs JPG for websites
| Image type | Best format | Why |
|---|---|---|
| Hero photos, blog images | JPG | Smaller file, faster LCP |
| Logos with transparency | PNG | JPG cannot do transparency |
| Icons, UI graphics | PNG or SVG | Sharp edges at small sizes |
| Screenshots with text | PNG | JPG blurs fine text |
How to convert PNG to JPG for your site
- Identify large PNG photos on your site (check PageSpeed Insights or your CMS media library).
- Open the PNG to JPG converter.
- Convert each photo PNG and re-upload the JPG to WordPress, Shopify, or your host.
- Update image references in your pages or let your CMS replace the file.
Core Web Vitals checklist
- Convert photo PNGs to JPG (or WebP if your CMS supports it)
- Resize images to the display size — don't serve 4000px wide images in a 800px slot
- Add
widthandheightattributes to prevent layout shift - Use lazy loading for below-the-fold images
FAQ
Does PNG slow down websites?
Yes, when used for photos. PNG files are often 5–10× larger than JPG for the same photographic content.
Should all website images be JPG?
No. Keep PNG for logos, icons, and transparent graphics. Convert photo PNGs to JPG.
Will converting PNG to JPG hurt SEO?
Faster pages help SEO. Converting bloated photo PNGs to JPG is a common speed optimization.