JPEG vs PNG compression.
JPEG and PNG are the two most common image formats on the web. Each is optimised for a different use case — choosing the wrong one wastes bandwidth, storage, and quality. Here is exactly when to use each.
Quick comparison
| Feature | JPEG | PNG |
|---|---|---|
| Compression type | Lossy (discards data) | Lossless (preserves all data) |
| File size (photo) | Small (200-600 KB for web) | Large (2-5 MB for same photo) |
| File size (screenshot) | Medium (100-400 KB) | Medium (200-800 KB) |
| Transparency | Not supported | Full alpha channel |
| Colour depth | 24-bit (16.7M colours) | 24-bit + 8-bit alpha (or indexed) |
| Text and sharp edges | Artefacts at low quality | Crisp and sharp |
| Animation | Not supported | Not supported (APNG limited) |
| Browser support | 100% | 100% |
| Best for | Photographs, gradients, web | Logos, screenshots, transparency |
When to use JPEG
JPEG is the default choice for photographs, product images, and any visual with smooth colour transitions. It achieves dramatic file size reduction — typically 80-90% — by discarding colour information that the human eye struggles to perceive. A photograph that is 5 MB as a TIFF or 15 MB as a PNG becomes 200-500 KB as a JPEG at quality 80, with no visible difference at normal viewing sizes.
JPEG uses a block-based DCT (Discrete Cosine Transform) algorithm that excels at compressing smooth gradients and fine textures. It is the standard format for digital cameras, web content, and social media. Use our JPEG compressor to optimise your JPEG images with Mozilla's mozJPEG encoder, which produces smaller files than standard JPEG at the same quality setting. For bulk photo optimisation, the bulk compressor processes hundreds of images in parallel.
When to use PNG
PNG is the right choice for images that need crisp edges, text legibility, or transparency. Logos, screenshots, UI elements, icons, and images with text overlays all benefit from PNG's lossless compression, which preserves every pixel exactly. PNG also supports an alpha channel for variable transparency — essential for logos that sit on different coloured backgrounds and UI assets.
PNG uses deflate compression (the same algorithm as ZIP) combined with per-row pixel filtering. For images with large uniform areas or limited colour palettes, PNG can achieve excellent compression ratios. Our PNG compressor supports both lossless mode (pixel-perfect output with optimised filtering) and lossy mode (colour quantization for dramatic size reduction on PNG photographs). For batch processing, use the bulk compressor.
JPEG vs PNG: file size comparison
A 12-megapixel photo (4000×3000px) from a modern smartphone: JPEG at quality 80: 400-800 KB. PNG lossless: 10-20 MB. Difference: PNG is 15-30× larger with no visual benefit for photographic content.
A 1920×1080 screenshot of a web page: JPEG at quality 80: 150-400 KB (visible artefacts around text). PNG lossless: 400-1200 KB (crisp text). Difference: PNG is 2-4× larger but text is sharp and perfectly readable.
A 512×512 logo with transparency: JPEG: Not suitable (no transparency support). PNG-32: 5-20 KB (lossless, transparent background). Winner: PNG is the only viable choice for logos and icons with transparent backgrounds.
Modern alternatives: WebP and AVIF
For new projects, consider WebP and AVIF, which offer the best of both worlds: small file sizes like JPEG with full transparency support like PNG. WebP is supported by 97% of browsers and typically produces files 25-35% smaller than JPEG. AVIF achieves 50% smaller files than JPEG with even better quality. Both support lossless and lossy compression with alpha channels.
Frequently asked questions
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Which is better for photos — JPEG or PNG?
JPEG is almost always better for photographs. It supports millions of colours with efficient compression, producing files 5-10x smaller than PNG at equivalent quality. PNG photographs are needlessly large — a 5 MB JPEG might be 15-25 MB as PNG.
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Which is better for screenshots — JPEG or PNG?
PNG is better for screenshots with text, UI elements, or sharp edges. The lossless compression preserves text clarity perfectly. JPEG introduces blurry artefacts around text at low quality settings. For screenshots, use PNG lossless compression — our tool reduces PNG size by 10-40% with no quality loss.
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Does JPEG or PNG support transparency?
Only PNG supports transparency (alpha channel). JPEG has no alpha support — areas that should be transparent appear white instead. For logos, icons, and overlays that need transparency, PNG is the only choice between these two formats.
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Can I convert between JPEG and PNG?
Yes — our compressor supports format conversion. Converting PNG to JPEG saves significant file size but loses transparency. Converting JPEG to PNG preserves every pixel but produces much larger files. Use our image converter tool for batch format conversion.
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Which format loads faster on websites?
JPEG loads faster on slow connections because the files are 5-10x smaller. However, PNG loads faster on fast connections for images with few colours (like flat-design icons) because the decoding is simpler. For photographs on any connection, JPEG is faster.
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Which format is better for printing?
PNG is preferred for printing when lossless quality is required — for logos, line art, and text. JPEG with minimal compression (quality 95-100) is fine for photographic prints. Most print shops accept both, but PNG avoids any risk of JPEG compression artefacts in the final print.
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