JPG vs PNG vs WebP vs AVIF: Which Image Format Should You Use in 2026?

Three years ago, picking an image format for the web was straightforward: JPG for photos, PNG for anything with transparency, and WebP if you were feeling ambitious. In 2026, the landscape is different. AVIF has crossed 95% browser support, WebP is universal, and the gap between these modern formats and JPEG/PNG has grown large enough to matter — often doubling the size of a page when you get it wrong. This guide walks through each format, shows the file-size differences with real numbers, and gives you a decision tree at the end.

1. JPEG (JPG): the universal photographic format

JPEG has been the default photographic format since 1992. It uses a discrete cosine transform (DCT) to compress images in 8×8 blocks, discarding high-frequency information that human vision is insensitive to. The compression is lossy — decoding a JPEG and re-encoding it at the same quality will lose a little more detail each round, a phenomenon called generational loss.

JPEG has no alpha channel (no transparency), maxes out at 8 bits per channel, and struggles with sharp edges, text, and flat colour regions — exactly the content that appears in screenshots, logos, and UI exports. For continuous-tone photographs, though, JPEG is still hard to beat on encoder speed and decoder compatibility. Every browser, every operating system, every image library on the planet reads JPEG correctly. That universality is worth something.

Use JPEG when: you need a photographic format that opens anywhere (email attachments, legacy systems, third-party services that don't accept WebP or AVIF), or when encoder speed matters more than file size (on-the-fly thumbnail generation at scale).

2. PNG: lossless with transparency

PNG was designed in 1996 specifically as a patent-free successor to GIF and a better option for lossless web graphics. It uses DEFLATE compression (the same algorithm as zip and gzip) applied to filtered pixel rows, which makes it efficient for images with large flat colour areas — UI elements, logos, diagrams, and screenshots with text.

Two features make PNG worth keeping in 2026. First, it supports an 8-bit alpha channel, so you can have smoothly anti-aliased transparency. Second, it's lossless: a PNG round-trips through encoders without any degradation, which matters if the file is going back into an editing pipeline. The cost is size: a photograph saved as PNG is typically 3–5× larger than the same photograph as a high-quality JPEG.

Use PNG when: you need lossless, universally-readable output with transparency — logos, UI assets, screenshots with readable text, intermediate editing files. For final web delivery, WebP (in its lossless mode) will almost always be smaller than PNG with the same visual result.

3. WebP: the modern default

Google released WebP in 2010 as a dual-mode format: VP8-based lossy compression for photographs (beating JPEG by roughly 25–35% at equivalent quality) and a VP8L-based lossless mode that typically outperforms PNG by around 26%. WebP also supports alpha transparency — something JPEG can't do — and animation, which makes it a viable replacement for animated GIFs too.

Safari held out on WebP support until iOS 14 and macOS Big Sur (2020), and that single gap was the main reason WebP adoption took a decade to feel "safe". As of 2026, every current browser supports WebP natively — Chrome, Firefox, Safari, Edge, Opera, and Samsung Internet — and the long tail of legacy browsers is negligible for most consumer sites.

Use WebP when: you want a single modern format with good file size, fast encoding, and near-universal browser support. It's the pragmatic default for most web imagery in 2026.

4. AVIF: the size king, with trade-offs

AVIF is an image container built on the AV1 video codec, standardised in 2019. On photographic content, AVIF typically delivers files that are 20–30% smaller than WebP at the same visual quality, and often more than 50% smaller than JPEG. It also supports HDR (10 and 12-bit colour), wide colour gamuts, and high-quality alpha transparency.

There are two caveats. First, AVIF encoding is slow — an order of magnitude slower than WebP in typical configurations — which makes it awkward for on-demand thumbnail pipelines unless you precompute. Second, browser support crossed 95% only recently: Safari added AVIF in version 16 (macOS Ventura, iOS 16, September 2022), so a small but real slice of users on iOS 15 and earlier cannot decode AVIF at all. In 2026, that tail is thin enough that AVIF is safe to serve as the primary format if you include a WebP or JPEG fallback.

Use AVIF when: file size is the top priority and you can either pre-encode offline or tolerate slow encoding. Always pair with a fallback for maximum compatibility.

5. File-size comparison on the same image

To give you a concrete anchor, here's what a typical 1920×1280 photographic image looks like encoded at roughly equivalent visual quality (SSIM ~0.95):

Exact numbers depend heavily on content and encoder settings — expect ±20% variation. Flat graphics and logos show even more dramatic differences in favour of lossless modes of WebP and AVIF.

6. Decision tree: which format should you use?

• Photograph on the public web → AVIF with a WebP fallback via the <picture> element. If you can't afford the AVIF encode cost, ship WebP as the primary format.
• Logo, UI asset, icon, screenshot with text → PNG for maximum compatibility, or WebP (lossless mode) for smaller size on the web.
• Need to email or attach the file → JPEG. Nothing else is as safely openable on every platform and client.
• Intermediate editing file → PNG or TIFF, never JPEG. Re-saving JPEG repeatedly loses detail each round.
• Animated content → WebP animation or MP4 in a <video> tag. Don't use GIF for new projects — it's larger and lower quality than both.

Frequently asked questions

References

• W3C Recommendation — Portable Network Graphics (PNG) Specification (3rd edition)
• ISO/IEC 10918-1 — JPEG (original 1992 standard, with later amendments)
• ISO/IEC 23008-12 — HEIF (container used by HEIC and shared with AVIF)
• IETF AV1 Image File Format (AVIF) — aomediacodec.github.io/av1-avif
• Google WebP project — developers.google.com/speed/webp
• MDN Web Docs — Image file type and format guide
• caniuse.com — AVIF / WebP browser support tables