Why Convert Formats
Your phone holds images in many formats — JPG for small files, PNG for transparency, WebP for balanced quality and size. Different scenarios call for different formats. Image Converter supports conversion between JPG, JPEG, PNG, WebP, BMP, and TIFF, all processed locally on your device without any loss in quality.
The Characteristics of the Six Formats
JPG / JPEG: Lossy Compression, Smallest Files
The most common photo format. Almost every camera and phone outputs JPG by default. JPG uses lossy compression, dropping details the human eye is less sensitive to in exchange for smaller files. Strengths: smallest file size and widest compatibility. Weaknesses: every re-save loses more detail, and transparency is not supported.
Typical uses: photo sharing, social media, web images.
PNG: Lossless Compression with Transparency
PNG uses lossless compression, so quality matches the original. It supports the alpha channel (transparency), making it the go-to format for icons, UI design files, and screenshots. Strengths: lossless quality with transparency support. Weaknesses: file sizes are 3–5× larger than JPG.
Typical uses: icons, logos, UI design files, and images that need a transparent background.
WebP: The Modern Web Format
A modern image format introduced by Google that balances quality and size. WebP is 25–35% smaller than JPG and compresses better than PNG. Strengths: small files with lossy, lossless, and transparency options. Weaknesses: compatibility on older devices is limited (natively supported on iOS 16+ and Android 5+).
Typical uses: web images, app assets, and any scenario where minimizing size is critical.
BMP: Bitmap, No Compression
A long-standing Windows format. BMP does not compress — every pixel is preserved. Strengths: lossless quality with good compatibility. Weaknesses: very large files, typically 5–10× the size of JPG.
Typical uses: built-in Windows tools and temporary files in professional software.
TIFF: Archival and Print Grade
A professional-grade image format. Lossless, multi-layer, with support for CMYK and other print color spaces. Strengths: top-tier quality with rich metadata. Weaknesses: very large files and weaker compatibility than JPG.
Typical uses: print and publishing, professional photography archives, and scanned records.
Preserving Quality During Conversion
- Same-format or same-class conversion: JPG ↔ WebP are both lossy, so no extra loss is added.
- JPG → PNG: pixels are copied over. File size grows but quality is preserved (lossless conversion).
- PNG → JPG: the alpha channel is dropped (filled with white). File size shrinks dramatically with quality intact.
- Any format → TIFF: lossless. The best quality and the largest files.
How Image Converter Handles Conversion
- Auto-detect the source format: Identified from both the file extension and the file signature (PNG 89 50 4E 47, JPEG FF D8 FF, WebP RIFF + WEBP).
- Correct EXIF rotation: iPhone photos with EXIF tags are rotated at the pixel level before conversion.
- Skip meaningless targets: The original format is excluded from the target list.
- Local processing: Everything happens on the device. Files are never uploaded.
Which Format to Choose: Quick Reference
| Scenario | Recommended Format | Why |
|---|---|---|
| WeChat Moments / Weibo sharing | JPG | Broad compatibility, small files |
| Screenshots / tutorials | PNG | Clear and sharp text |
| Web / app assets | WebP | Smallest files with good quality |
| Design files / logos | PNG | Transparency support, lossless quality |
| Print / archival | TIFF | Top-tier quality, complete metadata |
| Windows system workflows | BMP | Native system compatibility |
If you're still unsure which to pick, JPG is the safest choice — virtually every platform supports it and it keeps files small. The only trade-off is no transparency support.