Image Converter

Different programs want different image formats: an upload form insists on JPG, a website runs faster with WebP, Windows needs an ICO, a print shop asks for TIFF. This converter reads almost any image your browser can open — plus iPhone HEIC photos — and saves it as JPG, PNG, WebP, GIF, BMP, ICO or TIFF. Batch conversion works too, and nothing is uploaded.

How to use this tool

1. Drop one or more images. Mixed formats in one batch are fine.
2. Choose the target format and, for JPG or WebP, a quality (90% is near-lossless).
3. Decide about transparency: keep it for PNG, WebP, GIF, BMP, ICO and TIFF, or fill it with a background colour. JPG is always filled.
4. Optionally limit the long side, set the icon sizes for ICO, or a render width for SVG files.
5. Download each converted file or the whole set as a ZIP.

Formula

Decode (browser decoder, or libheif for HEIC) → draw on a canvas → encode in the chosen format

JPG, PNG and WebP use the browser’s own encoders. The others are written byte by byte on your device: BMP as 24-bit (or 32-bit BGRA with a V4 header when transparency is kept), ICO as PNG images inside an icon directory, GIF with a 256-colour palette (gifenc), and TIFF as a baseline uncompressed RGB or RGBA file. AVIF output is not offered because most browsers cannot encode it.

Example

A 512 × 512 px transparent logo PNG converted to ICO with sizes 16, 32, 48, 256 gives one .ico file of about 25–40 KB holding four PNG icons, ready for a website favicon or a Windows shortcut. The same logo saved as BMP with transparency switched off is a 24-bit file of exactly 54 + 512 × 1536 = 786,486 bytes (a 54-byte header plus 3 bytes per pixel).