How to Convert PNG to JPG in Shopify (and Why It Speeds Up Your Store)

PNG to JPG conversion is the single highest-impact image optimisation you can do for most Shopify stores. A product photograph saved as a PNG is typically 3–8 MB. The same photograph saved as a JPG at 80% quality is 200–500 KB. That’s a 90% reduction in file size with no visible quality difference on screen. Multiplied across every product image in your store, this is the difference between a fast store and a slow one.

Why PNGs Are Wrong for Shopify Product Photos

PNG is a lossless image format. It stores every pixel of data in the original file with no compression artefacts. This makes it the right choice for images that need pixel-perfect reproduction: logos, icons, graphics with sharp edges and flat colours, and anything with a transparent background.

Product photography is none of these things. A product photo is a continuous-tone image with gradients, shadows, highlights, and textures. Lossless compression for this type of content produces enormous files. JPEG, which uses lossy compression tuned to the characteristics of photographic content, achieves a dramatic size reduction with losses that are invisible to the human eye at normal viewing sizes.

The typical reason merchants end up with PNG product photos is that their photographer or retoucher exports in PNG by default, or because they’ve been told “PNG is better quality.” For product photography displayed on a screen, this is not true in any practical sense.

The Shopify WebP Misconception

Many Shopify merchants believe they don’t need to worry about image formats because Shopify automatically serves WebP. This is technically true but practically misleading.

WebP is a modern image format developed by Google that offers better compression than both JPEG and PNG. Shopify’s CDN does convert images to WebP for supporting browsers. But WebP is a container format — it wraps the compressed image data. If the source image is a 6 MB PNG, the WebP version is still a very large file because WebP preserves the lossless nature of the original PNG encoding.

Converting a PNG product photo to JPG before uploading, then letting Shopify’s CDN convert that JPG to WebP, produces a file 3–5× smaller than letting the CDN convert the original PNG to WebP.

How to Convert PNG to JPG in Shopify

There are several approaches:

Before upload: Convert images before uploading using Photoshop, GIMP, Squoosh (free web tool), or ImageMagick. This is the best practice for new product photography but doesn’t help with your existing product catalogue.

Bulk conversion of existing images: For an existing Shopify store with PNG product photos already uploaded, you need a tool that can identify PNG files, convert them to JPG, and replace them in your store without manual file management. AssetScope’s Image Optimiser does this — it identifies PNG files that should be JPGs, shows you a preview comparison, and saves the JPG version back to your Shopify store.

What to Check Before Converting

Before converting a PNG to JPG, verify two things: does the image require transparency? If there is a transparent background (a cutout product on white often uses transparency in the original file, even if it looks white on your storefront), converting to JPG will fill the transparent areas with a solid colour. For most product photos this is fine, but check.

Second: is the image referenced with a hardcoded URL anywhere in your theme? Converting and replacing an image changes its CDN URL. If your theme or a page builder references the old PNG URL directly, that reference will break. AssetScope’s replace workflow checks for theme references before proceeding.

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