Image Converter decodes a batch of images into pixels in the browser and repackages them with the encoder you choose — JPG, PNG or WebP — into new files. The input can be an iPhone HEIC, a WebP saved from a web page, or PNG, JPG, GIF, BMP or AVIF. Images are not uploaded.

It targets two problems: “the other side cannot open it” and “the format is not accepted”. An HEIC photo sent to a Windows colleague, a web image saved as WebP that will not go into an older office suite, a system that only accepts JPG uploads, a transparent logo that needs PNG.

The difference from “Image Compress” is the goal: that tool reduces size within one format, this one changes the format. Underneath, both use the same canvas encoding, so the lossy-versus-lossless rules, the quality parameter and what happens to metadata are identical — this page only covers what is specific to conversion; for the background see the how-it-works section of Image Compress.

1. 01Add imagesdrag them in, click to choose or paste, with multi-select supported; when HEIC is detected the page says “converting to JPEG…”, which is a local decode, so just wait a moment. The list shows each image's pixel dimensions and size.
2. 02Choose the target formatJPG (small, no transparency), PNG (lossless, with transparency), WebP (lossy with transparency, usually the smallest).
3. 03Set the encoding quality0.1–1, 0.9 by default; choosing PNG disables the slider and notes that “PNG is a lossless format, so this has no effect”.
4. 04Click “Start converting”the progress bar advances image by image; the result keeps the original name and only the extension changes.
5. 05Downloaduse the download icon for one image, or “Download as zip” for several.

Measured sizes for the same batch of five images converted to three formats (quality 0.9, plus the JPG and WebP results at 0.75):

Input                          Original   → JPG 0.9   → PNG       → WebP 0.9   → WebP 0.75   → JPG 0.75
photo-3000x4000.jpg (photo)    1.3 MB     1.6 MB      16.3 MB     1.3 MB       263 KB        1.1 MB
logo-800x600.png (transparent) 22.2 KB    23.7 KB*    38.1 KB     13.8 KB      10.5 KB       16.8 KB*
scan-1600x1200.webp            342.5 KB   555.9 KB    4.1 MB      378.9 KB     282.3 KB      261.5 KB
screenshot-1920x1080.png       21.7 KB    72.4 KB     56.2 KB     13.7 KB      13.0 KB       58.2 KB
logo-400x300.gif               5 KB       11.7 KB     13.5 KB     5.5 KB       3.9 KB        8.2 KB
                                          * transparent areas become white

Three conclusions: a photo converted to PNG balloons more than tenfold (1.3 MB → 16.3 MB) without getting any better; a screenshot or line art converted to JPG is actually larger and rings (a 21.7 KB PNG becomes a 72 KB JPG); and WebP near 0.75 is the smallest for almost every type, at the cost of compatibility with older software.

Lossy versus lossless, JPEG quantisation, why PNG has no quality parameter and what canvas encoding implies are all explained in Image Compress. This section covers only the three things specific to the conversion path.

The intermediate state is a block of bare pixels

Whatever the input, the browser first decodes it into RGBA pixels on a canvas. That step flattens every format difference and drops everything that is not a pixel: EXIF shooting data and GPS, colour profiles, the later animation frames of a GIF, layers and comments. The orientation flag has already been applied to the pixels at decode time, so a portrait photo will not come out sideways — but the flag itself no longer exists. When that information has to survive, conversion is not the right tool.

Where the transparency goes

The A (alpha) of the RGBA survives on the canvas, and whether it reaches the output depends on the target format: PNG and WebP support transparency natively and JPG has no alpha channel. Before writing a JPG the tool lays down white and then draws the image on top, so a transparent logo becomes a white-background logo (the two starred rows in the table). The three squares on the right of the SVG above are the same logo in three results: PNG at 38 KB keeps the transparency, JPG at 24 KB is on white, and WebP at 14 KB is both transparent and the smallest.

How HEIC gets in

HEIC/HEIF is the default photo format on Apple devices, built on HEVC video coding, and most browsers cannot decode it directly. When you add a file the tool decodes it locally with heic2any (the WebAssembly build of libheif) and encodes an intermediate JPEG at quality 0.92 before the normal conversion path. So HEIC → PNG gives you “a lossless wrapper around a lossy intermediate”, large in size and no better in quality than HEIC → JPG; HEIC → JPG is the ordinary route. The .heic in the file name is replaced with the target extension.

What the three encoders are for

• JPG: lossy, the quality parameter applies, no transparency. The first choice for photographs and the widest compatibility.
• PNG: lossless, the quality parameter is ignored, transparency preserved. The first choice for screenshots, icons, text and assets that will be edited again; a photograph should not go to PNG.
• WebP: this tool outputs lossy WebP, the quality parameter applies and transparency is preserved. At the same visual quality it is 25%–35% smaller than JPG and far smaller than PNG; browsers from before 2020, some office suites and some government upload systems do not recognise it.

GIF and BMP can only be inputs: a GIF contributes its first frame only and the animation is lost (use “GIF Edit” to work on animated images), and BMP is an uncompressed bitmap that shrinks dramatically in any other format.

• An iPhone photo album to Windows in bulk: drag a whole album of HEIC files in, target JPG, quality 0.9, download as a zip. It will be 30%–40% larger than HEIC — that is the efficiency gap between HEVC and JPEG, not damage.
• Preparing web images: target WebP at quality 0.75–0.8, which gives the smallest size for both photos and screenshots; keep a JPG or PNG copy as a fallback where WebP is not supported.
• Normalising transparent assets: unify the various formats a designer supplied into PNG for documents and slides; if they are only used on the web, WebP saves more.
• Convert first, then compress: conversion and compression chain together — convert a WebP scan to JPG, then use the target-size mode of “Image Compress” to get under an upload threshold.

Input

JPG / JPEG, PNG, WebP, GIF (first frame), BMP, AVIF (needs browser support), HEIC / HEIF (decoded locally).

Output

JPG, PNG, lossy WebP; no GIF, BMP, TIFF, AVIF or lossless WebP.

Quality

0.1–1 in steps of 0.05, 0.9 by default; no effect on PNG.

Dimensions

pixel dimensions are unchanged (use “Resize Images” first if you need that); browser canvas limits apply, so an image with a side beyond about 16,000 px or an extreme total pixel count may fail.

Metadata

EXIF, GPS and colour profiles are not preserved; orientation has already been applied to the pixels.

Transparency

preserved for PNG and WebP; a JPG output gets a white background.

File names

the original name is kept with the extension replaced; a same-format conversion such as JPG → JPG produces a file with the same name.

HEIC intermediate

decoded to a JPEG at quality 0.92 first, then converted to the target format.

What it does not do

it does not change dimensions, does not compress to a target size (use “Image Compress”), does not handle animated images, does not convert between SVG vectors and bitmaps, and does not batch rename.

• “Converting to PNG gives better quality”: PNG only stores the decoded pixels losslessly; the loss the JPEG already suffered does not come back, while the size can be more than ten times larger.
• “WebP works everywhere”: on the web it very nearly does, but it is often rejected when sent to other people or uploaded to an older system. JPG or PNG is safer for a file that leaves your hands.
• “Conversion keeps the shooting information”: it does not — EXIF and GPS are dropped together. Export it first with “EXIF Viewer and Remover” if you need to keep it.
• “A GIF converted to WebP stays animated”: this tool takes the first frame only; use “GIF Edit” or “GIF to Video” for animated images.

Decoding (including HEIC), canvas drawing and encoding all happen inside your browser; images are never uploaded and the tool works without a network connection. The output carries no EXIF and no GPS. See the privacy policy for more.

• MDN Web Docs, Image file type and format guide — compression type, transparency and animation support, and browser compatibility for each format: https://developer.mozilla.org/en-US/docs/Web/Media/Guides/Formats/Image_types（访问日期：2026-09-09）
• Google for Developers, WebP Container Specification — the lossy VP8 bitstream, the lossless mode and the ALPH transparency chunk: https://developers.google.com/speed/webp/docs/riff_container（访问日期：2026-09-09）
• RFC 2083, PNG (Portable Network Graphics) Specification — lossless compression and the alpha channel: https://www.rfc-editor.org/rfc/rfc2083（访问日期：2026-09-09）
• heic2any (GitHub) — a browser-side HEIC/HEIF decoder based on libheif, with its toType and quality parameters: https://github.com/alexcorvi/heic2any（访问日期：2026-09-09）