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画像ツール カテゴリ

画像形式変換ツール

JPGをPNGに、PNGをJPGにブラウザ内で変換します。透明部分には背景色を指定できます。

ツールを読み込み中…

このツールはブラウザ内で動作します。入力内容、ファイル、生成した値はこの端末に残ります。お気に入りと最近使ったツールを利用する場合も、ローカルストレージに保存されるのはツール名だけで、パスワード、文書、QR コードの内容は保存されません。 詳しくはプライバシーポリシーをご覧ください。

このツールの詳しい解説（使い方、例、よくある質問）は、現在英語のみでご用意しています。

What this tool does

Turn a JPG into a PNG, or a PNG into a JPG. Use it when a form or a site accepts only one of those formats. A clear PNG background is filled with the color you choose before it becomes a JPEG, and WebP is not converted here.

How to use

  1. Upload a JPG or PNG image.
  2. Choose JPG → PNG or PNG → JPG. The tool also lets you pick the output format directly.
  3. If you convert PNG to JPG, set a background color for transparent pixels. White is the default.
  4. Press Convert, then download the file.

Examples

  • JPG to PNG

    Useful when you need PNG for further editing. JPEG artifacts already in the file stay in the pixels.

  • PNG with transparency to JPG

    JPG has no alpha channel. Transparent pixels are filled with the background color you choose.

How it works

JPG is a lossy photo format without transparency. PNG is lossless and can include transparency. Converting JPG to PNG does not restore quality that JPEG already discarded. Converting PNG to JPG is also lossy. The conversion uses the browser canvas and stays on your device.

Limitations

JPG cannot store a transparent pixel, so a clear PNG background is filled with the color you choose before the JPEG is written. The reverse direction, JPG to PNG, keeps damage that JPEG already introduced. WebP, GIF, and HEIC are not converted here.

See the disclaimer for what these tools do not cover.

FAQ

Is the Image Converter free?
Yes. Turning a JPG into a PNG, or a PNG into a JPG, is free here, with no signup.
Is PNG to JPG lossless?
No. JPEG is a lossy format. Fine detail and sharp edges may change, and transparency becomes a solid background.
Is the file uploaded?
No. JPG and PNG conversion stays on this page. The file is not posted to a server.
Should I use PNG or JPG?
Use JPG for photos, where a smaller file matters more than perfect edges. Use PNG for logos, screenshots, text, and anything that needs a transparent background.
Why did my transparent background turn white?
JPG cannot store transparency, so transparent pixels are filled with a background color when you convert PNG to JPG. White is the default, and you can choose another color.
Does it work on mobile?
Yes. You can open this page on a phone or tablet. File pickers and downloads use the browser on your device. Large files may be slower on a small phone than on a desktop.

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