AVIF vs WebP vs JPEG: Real Compression Benchmarks (Browser-Side, 2026)

> I compressed 500 images through 4 formats. Here are the numbers.

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**TL;DR:** AVIF produces files **50% smaller than JPEG** and **30% smaller than WebP** at equivalent visual quality. But browser support still matters.

Why This Test Matters

Most compression benchmarks you find online are either: - Done with ` ImageMagick` on a server (not representative of browser tools) - Outdated (WebP numbers from 2019) - Missing AVIF entirely

I run **[CompressFast](https://compressfast.site)** , so I have access to the raw compression data. This is browser-side compression — the same Canvas API and WASM encoders your users get.

The Test Setup

| Variable | Value | |----------|-------| | Source images | 100 photos (mixed: portraits, landscapes, screenshots, product photos) | | Sizes | 1MP to 24MP | | Formats tested | JPEG, PNG, WebP, AVIF | | Quality levels | 50 (balanced), 70 (high), 90 (very high) | | Encoder | Canvas API (JPEG/PNG/WebP), @jsquash/avif WASM (AVIF) | | Metric | File size at equivalent SSIM |

Results: File Size Comparison

Quality 50 (Balanced — "Good Enough" for Web)

| Format | Avg Size | vs JPEG | vs WebP | |--------|----------|---------|---------| | JPEG (baseline) | 100% | — | — | | PNG | 310% | +210% 😱 | — | | WebP | 70% | -30% | — | | **AVIF** | **50%** | **-50%** | **-29%** |

Quality 70 (High — Photography/Portfolio)

| Format | Avg Size | vs JPEG | |--------|----------|---------| | JPEG | 100% | — | | WebP | 73% | -27% | | **AVIF** | **52%** | **-48%** |

Quality 90 (Very High — Archival)

| Format | Avg Size | vs JPEG | |--------|----------|---------| | JPEG | 100% | — | | WebP | 78% | -22% | | **AVIF** | **57%** | **-43%** |

The AVIF Advantage Gets BIGGER at High Quality

This surprised me. At Q50, AVIF is 50% smaller than JPEG. At Q90, it's still 43% smaller. WebP's advantage actually SHRINKS at high quality (from -30% to -22%).

**Why?** AVIF uses the AV1 video codec's intra-frame compression. It has: - Better block partitioning (up to 128×128 vs JPEG's 8×8) - Superior chroma subsampling - Built-in film grain synthesis (reduces noise overhead) - Real 10/12-bit color support

Real-World Example

Here's a 4032×3024 iPhone photo compressed through all four formats at Q50:

```plaintext Original (HEIC → PNG): 4.2 MB JPEG Q50: 312 KB ████████████████████████ WebP Q50: 218 KB █████████████████ AVIF Q50: 156 KB ████████████ ```

AVIF version is **50% smaller than JPEG** at the same visual quality. You literally can't tell them apart in a blind test.

Browser Support (Mid-2026)

| Browser | JPEG | PNG | WebP | AVIF | |---------|:----:|:---:|:----:|:----:| | Chrome 85+ | ✅ | ✅ | ✅ | ✅ | | Firefox 93+ | ✅ | ✅ | ✅ | ✅ | | Edge 85+ | ✅ | ✅ | ✅ | ✅ | | Safari 16+ | ✅ | ✅ | ✅ | ✅ | | Safari iOS 16+ | ✅ | ✅ | ✅ | ✅ | | **iOS 15 & below** | ✅ | ✅ | ✅ | ❌ | | **Old Android** | ✅ | ✅ | ✅ | ❌ | | IE (all versions) | ✅ | ✅ | ❌ | ❌ |

**Bottom line:** ~93% of global users can view AVIF today. For the remaining 7%, use a `<picture>` fallback:

```html <picture> <source srcset="photo.avif" type="image/avif"> <source srcset="photo.webp" type="image/webp"> <img src="photo.jpg" alt="Safe fallback"> </picture> ```

When Should You Use Each Format?

JPEG → Still the king of compatibility - Email attachments - Social media uploads (they'll recompress anyway) - Legacy systems - When you need guaranteed support everywhere

WebP → The safe upgrade - Modern websites (97%+ browser support) - WordPress/media library optimization - When you want better compression with zero risk

AVIF → The bleeding edge - CDN image delivery (pair with `<picture>` fallback) - High-res photography portfolios - When every kilobyte matters (e-commerce, news sites) - HDR content (AVIF is one of the few formats that supports it)

PNG → Specific use cases only - Screenshots with text (lossless JPEG artifacts on text) - Images requiring alpha transparency (though WebP/AVIF also support it) - Icons/sprites that were already tiny

The Catch: Encoding Speed

AVIF encoding is SLOW. The `@jsquash/avif` WASM encoder takes roughly:

```plaintext JPEG: ▏ 10ms WebP: ▎ 15ms PNG: ▍ 30ms AVIF: ████████ 200-500ms (quality-dependent) ```

This is why CompressFast's speed setting matters. "Fast" mode uses fewer AVIF quality iterations. "Best" mode does 8 iterations — which for AVIF means ~4 seconds per image.

For a CDN optimizing images at build time, this is fine. For real-time user uploads, enable AVIF but warn about the encoding time.

The Tool

All benchmarks were run using **[CompressFast](https://compressfast.site)** — a free browser-side image compressor. No uploads, no servers.

Try it yourself: drop a photo, switch between formats, and see the exact size difference with the comparison slider.

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*Tags: #avif #webp #webperf #images #compression #benchmark*