What's the ideal size for a web image?

Aim for under 200 KB for main images and under 100 KB for secondary images. Dimensions depend on your layout.

Is WebP really better for the web?

Yes, WebP offers 25-35% better compression than JPG. All modern browsers have supported it since 2020.

How do I optimize images for mobile?

Use responsive images (srcset), compress more (70-75% quality), and favor WebP format.

Does lazy loading affect SEO?

No, Google understands lazy loading. Use loading='lazy' natively or an SEO-compatible library.

Should I convert all my images to WebP?

For modern web, yes. Provide a JPG/PNG fallback for rare cases of incompatibility with the tag.

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ConvertlyPICTURE

Optimize images for your website

Complete guide to optimize images for your website: compression, formats, dimensions and best practices for fast loading.

ConvertlyPicture · August 13, 2026

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Easy access with no mandatory account for essential tools and a processing method suited to each tool.

Use Compress an image

Images often represent more than 50% of a web page's total weight. Their optimization is therefore essential for your site's performance and SEO.

An unoptimized image can weigh several megabytes and take several seconds to load, driving away visitors and hurting your Google rankings.

discover all professional techniques to optimize your web images and improve your loading speed.

Why image optimization matters for SEO

Google uses Core Web Vitals to evaluate site performance. Images directly impact the Largest Contentful Paint (LCP).

A slow site drives away visitors: 53% of mobile users abandon a site that takes more than 3 seconds to load.

Reducing image weight also decreases your bandwidth and hosting costs.

Choosing the right image format

WebP: the best overall choice, 25-35% lighter than JPG with equivalent quality. Compatible with all modern browsers.

JPG: ideal for photos, good size/quality compromise. Use 75-85% quality.

PNG: reserve for images with transparency or simple graphics.

SVG: perfect for logos, icons, and illustrations. Scalable.

Advanced optimization techniques

Responsive images: serve different sizes based on device with srcset and sizes.

Lazy loading: load off-screen images only when they come into the viewport.

CDN with optimization: use a CDN that optimizes and resizes images on the fly.

Measuring optimization impact

Use Google PageSpeed Insights to identify images to optimize.

Test on a slow connection (Chrome DevTools Network tab) to see the real impact.

Recommended tools

Compress an image

Reduce image file size with an adjustable quality level. You can select up to 50...

Convert an image Resize an image

How to do it in 3 steps

Resize your images to the maximum necessary dimensions (no more than 1920px for banners, 1200px for content).

Upload your images to our compression tool and choose an appropriate quality (75-85% for photos).

Download the optimized images and implement lazy loading on your site.

Pro tips

Keep an original version.
Test several quality settings.
Use WebP when possible.
Choose a descriptive file name.

Common mistakes to avoid

✗Uploading full resolution images (4000+ pixels) to display them at 800px.
✗Using PNG for photos instead of JPG or WebP.
✗Not implementing lazy loading for images below the fold.
✗Forgetting to compress CSS background images.

Frequently asked questions

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