画像変換ツール
Client-Side Only画像形式を変換・最適化します。
🔒 Privacy-First Design: Your images never leave your device. All conversion and resizing happens client-side using Canvas API.
📤 Upload Image
Drop image here or click to browse
Supports: PNG, JPG, WebP, GIF
🔄 Convert Format
PNG
Lossless
JPG
Smaller size
WebP
Modern
GIF
Animation
📏 Resize Image
📷 Original Image
No image uploaded
✨ Converted Image
Convert to see result
Multiple Formats
Convert between PNG, JPG, WebP, and GIF formats with quality control
Flexible Resizing
Resize by percentage, dimensions, or max width/height with aspect ratio control
Instant Processing
Client-side processing using Canvas API - no uploads, instant results
Image Formats Compared (PNG/JPEG/WebP)
Choosing the right image format is crucial for web performance and visual quality. JPEG is best for photographs and complex images with many colors, as it uses lossy compression to achieve small file sizes. PNG is ideal for images that require transparency or have sharp edges and solid colors (like logos and icons), as it uses lossless compression.
WebP is a modern format that provides superior lossy and lossless compression, often resulting in significantly smaller file sizes than JPEG or PNG while maintaining high quality.
How to Use This Tool
- Upload your image by dropping it into the Upload Image zone or clicking to browse your files.
- Select your desired output format (PNG, JPG, WebP, or GIF) from the Convert Format options.
- If you have selected a lossy format like JPG or WebP, use the quality slider to balance file size and visual fidelity.
- Optionally, use the Resize Image settings to scale your image by percentage or specific dimensions.
- Click Convert & Resize Image and then Download to save your optimized asset.
Common Use Cases
- Web Optimization: Convert large PNG or JPEG images to WebP to improve your website load speed and Core Web Vitals.
- Social Media: Resize and compress photos to meet the specific upload requirements of platforms like Instagram, Twitter, or LinkedIn.
- Email Marketing: Reduce the file size of images in your email campaigns to ensure they load quickly for all recipients.
- App Development: Generate multiple sizes of the same icon or asset for different screen densities using the resizing features.
Pro Tips
- Use WebP whenever possible for web projects, as it is supported by all modern browsers and offers the best compression-to-quality ratio.
- When converting to JPEG, a quality setting of 70-80% usually provides the best balance between file size and visual quality for most web uses.
- Always keep your original high-resolution images and only convert or resize copies for specific use cases to avoid losing quality over time through repeated compression.