Image Format Converter

about this tool

In: almost anything, including HEIC

Drop PNG, JPEG, WebP, AVIF, GIF or BMP files and the browser decodes them natively, with EXIF orientation applied. HEIC — the format iPhones shoot in, which no browser but Safari can read — is recognised by its name and by the ftyp box in its first bytes (its MIME type is usually blank), and decoded by libheif, about a megabyte, fetched the first time a HEIC file is dropped and then kept. TIFF is accepted where the browser can decode it, which today means Safari. SVGs are pointed at the SVG optimiser; they are vector, and this tool works in pixels.

Out: six formats

PNG, JPEG, WebP and AVIF come from the browser's own encoders, so AVIF and WebP are offered only where the browser can write them; the tool asks a canvas and greys out the rest. BMP has no browser encoder, so the tool writes it: standard 24-bit uncompressed, bottom-up rows padded to four bytes, which every program that has ever opened a BMP can read. ICO is a single-image Windows icon: the centre square of the image, scaled to at most 256 px, stored as a PNG entry in the ICO container the favicon generator also uses.

Lossy outputs take a quality setting; outputs without transparency — JPEG and BMP — take a background colour for what was transparent. An optional longest-side limit resizes on the way through, never upscaling. Each file is renamed with the new extension and downloaded alone or in a zip, with duplicate names numbered.

Batches

Files are converted one after another so a folder of holiday photos does not lock the page, with the stage shown per file (decoding, converting), and any change to the settings re-runs the batch under a run token that throws away stale results. Metadata does not survive: EXIF, GPS location and colour profiles are gone, and the pixels are sRGB.

Limits

No GIF or TIFF output; animated GIFs convert their first frame. AVIF encoding depends on the browser (Chrome and Firefox can, Safari cannot). HEIC decoding is the slowest step and the decoder is a large download the first time. The canvas size limit, around 16 000 px a side, bounds very large images, and a 36-megapixel BMP is a 108 MB file whatever you do. Nothing is stored.

To squeeze more out of a file at the same format, use the image compressor. Vector sources have their own route: SVG to PNG/JPG.

questions

How do I convert HEIC photos from an iPhone to JPG?

Drop them here and choose JPEG. Browsers other than Safari cannot read HEIC, so a decoder (libheif, about a megabyte) is fetched the first time you drop one and runs in your browser; the photos are never uploaded. Live Photos and bursts convert their main image.

Which format should I convert to?

WebP for anything going on a web page: it is smaller than both JPEG and PNG, keeps transparency and every current browser shows it. PNG when you need lossless quality or the file is a graphic with sharp edges. JPEG for photos where WebP is not accepted. AVIF is smaller still but only some browsers can write it, and the tool greys it out where yours cannot.

What happens to transparency when converting to JPEG or BMP?

Neither format has an alpha channel, so transparent areas are filled with the background colour you choose — white unless you change it. PNG, WebP, AVIF and ICO keep transparency.

Why is BMP so large?

Because it is uncompressed: three bytes per pixel, so a 4000 × 3000 photo is 36 MB regardless of content. It exists for old software and embedded devices that read nothing else. The converter writes standard 24-bit BMP, which everything reads.

Can I convert to GIF or TIFF?

Not here. Browsers have no GIF or TIFF encoder and writing them well is a project of its own; GIF is also limited to 256 colours, which makes it a poor target for photos. Both are accepted as input where the browser can decode them — GIF everywhere, TIFF in Safari.