PrestaShop Image Optimization: Sizes, Quality Settings & Performance Guide
PrestaShop generates more image variants per product than most ecommerce platforms -- seven or more size crops from every upload. That means an unoptimized 2MB product photo turns into 14MB+ of image data on the server. Controlling file sizes starts with the right source image dimensions and compression settings in the PrestaShop back office.
PrestaShop Image Size Configuration
In PrestaShop, image sizes are configured under Design > Image Settings. Each "image type" maps to a specific display context (product page, home page, category listing, cart). The default dimensions vary by theme, but the values below represent the PrestaShop 8.x defaults that work with the Classic theme.
| Image Type | Dimensions | Max File Size | Format |
|---|---|---|---|
| Product (main) | 800 x 800 px | 150 KB | JPG, WebP |
| Small thumbnail | 125 x 125 px | 15 KB | JPG, WebP |
| Large thumbnail | 458 x 458 px | 80 KB | JPG, WebP |
| Home page | 250 x 250 px | 40 KB | JPG, WebP |
| Category header | 870 x 217 px | 100 KB | JPG, WebP |
According to the PrestaShop 8 developer documentation, you can add custom image types or modify existing ones, but changing dimensions on a live store requires regenerating all thumbnails afterward. Plan this step for low-traffic periods.
Why Default Quality 90 Is Too High
By default, PrestaShop's JPG compression quality is set to 90 out of 100. At this level, an 800x800 product image weighs roughly 250KB. The same image at quality 80 weighs 160KB -- a 36% reduction -- with no visible difference on screen. Since PrestaShop generates 7+ variants per product, this quality change cascades across the entire catalog.
A store with 1,000 products and 5 images each at quality 90 stores approximately 8.75GB of generated thumbnails (1,000 x 5 x 7 variants x 250KB). At quality 80, that drops to approximately 5.6GB. The 3GB difference translates directly to faster page loads and lower hosting costs.
Compression Workflow for PrestaShop
- Lower the default JPG quality from 90 to 80. Go to Design > Image Settings in the back office. This single change reduces file sizes by 30-40% across all generated image variants with no perceptible quality difference on screen.
- Compress source images before uploading. Upload product photos through a lossless compression tool first. PrestaShop generates 7+ variants per image, so a smaller source file produces smaller variants across the board. Target 150KB or less for the source image.
- Switch from GD to ImageMagick. PrestaShop defaults to PHP GD for image processing, which produces lower-quality output than ImageMagick at the same file size. If your hosting supports ImageMagick, enable it in Advanced Parameters > Performance for sharper thumbnails.
- Regenerate thumbnails after theme or setting changes. Go to Design > Image Settings and click Regenerate thumbnails after changing themes or modifying image dimensions. For catalogs over 500 products on shared hosting, run regeneration during off-peak hours to avoid timeout errors.
Multi-Language Alt Text
For multi-language PrestaShop stores, separate alt text per language is available through the product editing interface. Search engines index alt text for each locale, so translating alt text improves image search visibility in each market. Avoid leaving alt text blank for non-default languages -- PrestaShop does not fall back to the default language automatically in all theme configurations.
Frequently Asked Questions
What image sizes does PrestaShop use for products?
PrestaShop uses multiple image sizes per product: 800x800 for the main product view, 458x458 for large thumbnails, 250x250 for home page display, 125x125 for small thumbnails, and 870x217 for category headers. These dimensions are configurable in Design > Image Settings in the back office.
Why does PrestaShop thumbnail regeneration time out?
Thumbnail regeneration times out on shared hosting when the catalog exceeds 500 products because PrestaShop must rebuild 7+ image variants per product. Each regeneration cycle requires substantial CPU and memory. Solutions include running regeneration during off-peak hours, increasing PHP max_execution_time to 600 seconds, or regenerating one image type at a time instead of all types simultaneously.
Should I change PrestaShop default JPG quality from 90?
Yes. PrestaShop defaults to JPG quality 90, which produces files 30-40% larger than quality 80 with no visible difference on screen. Lowering the setting to 80 in Design > Image Settings reduces page weight across your entire catalog. For stores with thousands of products, this change alone can cut total image bandwidth by a third.
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