JPG vs PNG: Which Image Format is Best for Your Website?

The Core Difference

JPG and PNG use different compression strategies built for different types of images.

JPG uses lossy compression — ideal for photographs with millions of gradual colour variations. The compression exploits the fact that humans cannot notice slight colour inaccuracies in realistic scenes.

PNG uses lossless compression — every pixel is stored exactly. Ideal for images with sharp colour transitions: logos, icons, text on a background, UI screenshots.

File Size Comparison

For a 1000x1000 pixel image:

• A photograph as JPG: ~150KB
• The same photograph as PNG: ~800KB–1.5MB
• A logo as PNG: ~25KB
• The same logo as JPG: ~80KB with visible artifacts around edges

The Rule

Use JPG when: The image is a photograph or realistic image, transparency is not needed, and you want the smallest file size.

Use PNG when: The image has text, sharp edges, or flat colours, transparency is needed, or you plan to edit the image further.

What About WebP?

WebP combines the advantages of both: it can be lossy like JPG or lossless like PNG, it supports transparency, and it is smaller than either format. If you are building a website today, convert your images to WebP for best performance.

File Size in Real Scenarios

A 1200×800 product photo exported from a camera:

• PNG: approximately 1.5–2.5 MB
• JPG (quality 85%): approximately 150–300 KB

The JPG is 8–10× smaller. For a page with 20 product images, this difference is 24 MB vs 4 MB — a dramatic impact on page load time.

A screenshot of a user interface with text and icons:

• PNG: approximately 200–400 KB (varies by colour complexity)
• JPG (quality 85%): approximately 100–200 KB but with visible compression artifacts around text edges

For the UI screenshot, PNG is the right choice despite the size difference — JPG's artifacts around sharp text edges are visible and look unprofessional.

Transparency: PNG's Exclusive Feature

PNG supports alpha channel transparency — pixels can be fully transparent, fully opaque, or anywhere in between. This is essential for logos, icons, cutout product photos, and any image that needs to sit on different coloured backgrounds without a white box around it.

JPG does not support transparency. A JPG on a webpage always has a solid background colour (typically white). For any image requiring transparency, PNG is required. WebP is an alternative that supports transparency while being smaller than PNG.

Repeated Editing

JPG is lossy — every save slightly degrades the image. This is invisible for one or two saves but accumulates over many generations. If you're editing an image repeatedly (cropping, adjusting, annotating), save it as PNG during the editing process and export to JPG only for the final web version.

PNG is lossless — you can save and re-open thousands of times with no degradation.

The Practical Decision Tree

1. Does the image need a transparent background? → PNG
2. Is it a photo or complex-colour image for web? → JPG (or WebP if modern browser support is confirmed)
3. Is it a screenshot, UI element, or image with text? → PNG
4. Will you be editing it repeatedly? → PNG for working file, JPG for final export
5. Is file size the overriding concern for a photo? → JPG or lossy WebP

Frequently Asked Questions

Can I use JPG for logos on my website? Only if the logo has a solid background and doesn't require transparency. For logos with transparent backgrounds (the standard for web use), PNG or WebP is required.

Does converting a JPG to PNG improve its quality? No. Converting from JPG to PNG stores the existing image losslessly but cannot recover quality that was already lost during JPG compression.

Should I accept PNG uploads from users on my website? Yes, but convert them to WebP or JPG on your server before serving them to other users. Storing and serving large PNGs for photographic content wastes bandwidth.

What about AVIF — is it better than both? AVIF (AV1 Image File Format) achieves even better compression than WebP. Browser support is nearly universal in 2025. For new projects, AVIF is worth evaluating alongside WebP.