Image Converter
Convert between JPG, PNG, WebP & AVIF — instant, free, private
Drop images here or click to browse (up to 10)
JPEG, PNG, WebP, AVIF up to 50MB each
How It Works
Drop Your Images
Drop up to 10 images at once, paste from clipboard, or click to browse. Krunkit detects each format automatically.
Choose Output Format
Select your target format from the settings panel. Adjust quality with the slider.
Download Converted Files
Download converted files individually, or grab all results as a single ZIP.
Which Format Should You Use?
JPEG (.jpg)
Best for photos with complex colors and gradients. No transparency support. Widely compatible with all devices and browsers. Typical savings: 60–80% vs. PNG.
PNG (.png)
Best for logos, screenshots, and images requiring transparency (alpha channel). Lossless compression preserves every pixel. Larger file sizes than JPEG for photos.
WebP (.webp)
Google's modern format. ~30% smaller than JPEG at equivalent quality. Supports transparency like PNG. Ideal for web use. Supported by all modern browsers since 2020.
AVIF (.avif)
The newest and most efficient format. Up to 50% smaller than JPEG. Excellent HDR and wide color gamut support. Supported by Chrome 85+, Firefox 93+, Safari 16+.
How Image Conversion Works
The Decode-Encode Pipeline
Image conversion is a two-step process: first the source file is decoded into raw pixel data (an uncompressed bitmap), then that pixel data is re-encoded into the target format. Krunkit performs both steps entirely in your browser using WebAssembly-compiled codecs. The decoded image exists only in memory as an HTML Canvas ImageData object — an array of RGBA values for every pixel. This intermediate representation is format-agnostic, which is why you can convert between any supported format pair.
Understanding Format Trade-offs
Each image format makes different trade-offs between file size, quality, features, and compatibility. JPEG excels at compressing photographs using DCT-based lossy compression, achieving small files but sacrificing transparency support. PNG preserves every pixel losslessly and supports alpha transparency, at the cost of larger files. WebP combines lossy and lossless modes with transparency, offering 25-35% smaller files than JPEG. AVIF pushes compression efficiency further with AV1-based encoding, supporting HDR and wide color gamut at the cost of slower encoding speed.
Handling Transparency During Conversion
When converting from a format that supports transparency (PNG, WebP, AVIF) to one that doesn't (JPEG), the alpha channel must be resolved. Krunkit automatically detects transparent pixels in your source image and prompts you to choose a background color — white, black, or a custom value. This color fills the transparent areas before encoding. Converting in the other direction (JPEG to PNG) doesn't add transparency; the image becomes a fully opaque PNG that can then be edited in a graphics tool to add transparent regions.
Quality and Generation Loss
Converting between two lossy formats (e.g., JPEG to WebP) involves re-encoding, which introduces a small amount of additional quality loss called generation loss. Each lossy encode-decode cycle degrades the image slightly, similar to photocopying a photocopy. To minimize this, use the highest quality setting when converting between lossy formats. Converting lossy-to-lossless (JPEG to PNG) preserves the current state perfectly but cannot restore quality already lost. For critical work, always keep your highest-quality original and convert from that source.
Frequently Asked Questions
Does converting images reduce quality?
Converting from a lossless format (PNG) to a lossy one (JPEG, WebP, AVIF) will involve some quality tradeoff, which you control with the quality slider. Converting between two lossless formats or keeping the same format with quality 100 is lossless.
What happens when I convert a PNG with transparency to JPEG?
JPEG doesn't support transparency. Krunkit detects transparent images and lets you choose a background color (white, black, or custom) to flatten the alpha channel before converting.
Is WebP better than JPEG?
For web use, yes. WebP produces files 25–35% smaller than JPEG at the same visual quality, and also supports transparency. All modern browsers have supported WebP since 2020. Use JPEG only for maximum compatibility with very old software.
Should I use AVIF or WebP?
AVIF is newer and more efficient (typically 20–30% smaller than WebP), but has slightly less browser support. For maximum performance, use AVIF. For broad compatibility including older browsers, use WebP.
Can I convert multiple images at once?
Yes! Drop up to 10 images at once, or paste from your clipboard. All files are converted with the same output format and quality settings. Download individually or as a single ZIP.