Format Overviews
JPEG (Joint Photographic Experts Group)
Standardised in 1992 and still the most widely used photographic image format, JPEG achieves small file sizes through lossy compression based on Discrete Cosine Transform. It divides images into 8×8 pixel blocks, converts to frequency space, and discards high-frequency detail that is less perceptible to human vision.
JPEG is universally compatible — every device, browser, operating system, and application supports it. Its weakness is that it does not support transparency, produces visible artefacts (blocking, ringing) at high compression ratios, and each save introduces additional quality degradation.
PNG (Portable Network Graphics)
PNG was developed in 1995 as an open-standard alternative to the patented GIF format. It uses lossless compression (DEFLATE), meaning no image data is discarded. PNG is ideal for images requiring perfect reproduction and transparency support.
PNG excels with graphics that have flat colour areas, sharp edges, and text — logos, screenshots, icons, and illustrations. For photographs, PNG's lossless approach produces much larger files than JPEG at comparable visual quality, making it a poor choice for photographic web images.
WebP (Web Picture Format)
WebP was developed by Google and formally announced in 2010. It supports both lossy and lossless compression, transparency (alpha channel), and animation. Google's WebP documentation describes it as achieving 25–35% smaller files than JPEG at equivalent quality for lossy compression, and 26% smaller files than PNG for lossless compression.
WebP is now supported in all major browsers (Chrome, Firefox, Safari 14+, Edge, Opera), making it a practical choice for most web projects in 2025. For email, desktop software, and older systems, JPEG and PNG remain safer choices due to their universal compatibility.
Full Comparison Table
| Feature | JPEG | PNG | WebP |
|---|---|---|---|
| Compression type | Lossy only | Lossless only | Lossy or Lossless |
| Transparency support | No | Yes (full alpha) | Yes (full alpha) |
| Animation support | No | No (use APNG) | Yes |
| Colour depth | 8-bit (24-bit RGB) | 1–48 bit | 8-bit (lossy), up to 8-bit lossless |
| Typical photo file size (vs JPEG) | Baseline | Larger (lossless) | 25–35% smaller |
| Typical graphic file size (vs PNG) | Sometimes smaller | Baseline | ~26% smaller (lossless) |
| Browser support | Universal | Universal | All modern browsers (2025) |
| OS / software support | Universal | Universal | Good, not universal |
| Best for photographs | Yes | Not ideal (large files) | Yes (best option) |
| Best for logos/graphics | No (artefacts on edges) | Yes | Yes |
| Best for screenshots | No (text artefacts) | Yes | Yes (lossless mode) |
| Accumulated quality loss on re-save | Yes | No | Yes (lossy mode) |
File Size: The Numbers Behind the Formats
The practical difference between formats is most visible in real file sizes. As a concrete example, consider a 1200×800px full-colour photograph:
- JPEG at 85% quality: approximately 180–250KB
- PNG (lossless): approximately 900KB–2MB (no quality loss, but large)
- WebP at equivalent quality: approximately 120–180KB (25–35% smaller than JPEG)
- WebP lossless: approximately 700KB–1.5MB (smaller than PNG, larger than lossy JPEG)
For a logo or flat graphic at 500×200px:
- JPEG: May have visible artefacts on edges; file size varies significantly
- PNG: approximately 15–50KB (lossless, excellent quality)
- WebP lossless: approximately 12–40KB (26% smaller than PNG on average)
Best Format by Use Case
Website Photography and Hero Images
Use WebP as the primary format with JPEG fallback via the HTML <picture> element. This gives modern browsers the smaller WebP file while older systems fall back to JPEG.
Product Thumbnails and Content Images
Use WebP or JPEG. For e-commerce product images on white backgrounds, compressed JPEG or WebP both work well. If the product photo has a transparent background (already processed with a background remover), use WebP or PNG to preserve the transparency.
Logos and Brand Assets
Use SVG whenever possible — it scales perfectly to any size and has tiny file sizes. For raster logos that need transparency, use WebP or PNG. Never use JPEG for logos.
Screenshots and UI Documentation
Use PNG or WebP lossless to preserve sharp text and interface details. JPEG's blocking artefacts on text are very noticeable and make screenshots look unprofessional.
Email Images
Use JPEG for photographs and PNG for graphics in emails. Email clients have inconsistent WebP support in 2025 — JPEG and PNG are safer choices for mass-distributed email campaigns.
Social Media
Most social platforms accept JPEG and PNG for uploads and handle conversion internally. Upload JPEG for photographs and PNG for graphics with transparency. Most platforms will re-compress images on their servers anyway, so the input format matters less than for web pages you control.
How to Convert Between Formats
ToolMasta's free image format converter converts between JPEG, PNG, WebP, BMP, and other formats. Simply upload your image, select the output format, and download the converted file. No account needed, no watermarks.
For compressing images after conversion, use the image compressor. For understanding compression in depth, read our guide on how to compress images for web without losing quality.
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