Convert JPG to ICO: Free Online Converter
Convert JPEG Image to Windows Icon online for free. Fast, secure image conversion with no watermarks or registration.
JPGに対応
アップロードすることで、これらのファイルの権利を有していること、および利用規約に同意することを確認したものとみなされます。
変換設定: ファイルを追加すると調整できます
安全な転送
HTTPS暗号化アップロード
プライバシー優先
ゲストのファイルは約2時間で自動削除
登録不要
すぐに変換を開始
どこでも動作
あらゆるブラウザ、あらゆるデバイス
JPG から ICO への設定
- エンジン
- 画像
- 設定
- 調整できる設定: 3
- Icon Size
- Rotate upright
- Strip Metadata
変換方法
アップロードエリアにドラッグするか、クリックして選択し、.jpgファイルをアップロードしてください。
必要に応じて出力設定を調整してください。デフォルト設定ではオリジナルの品質を維持します。
「変換」をクリックし、準備ができたら.icoファイルをダウンロードしてください。
JPGからICOへの変換について
ICO (Windows Icon) is the standard image format for desktop icons, favicons, and application shortcuts on Windows. A single ICO file can contain multiple image sizes (16x16, 32x32, 48x48, 256x256) embedded together, allowing Windows to select the appropriate resolution for each display context: taskbar, desktop, file explorer, and high-DPI screens. Converting JPG to ICO takes your photograph or graphic and produces a multi-resolution icon file ready for use in Windows applications, websites, and software projects.
Favicons (the small icons displayed in browser tabs and bookmark lists) are the most common use case. While modern browsers accept PNG and SVG favicons, the ICO format remains the most universally supported option, working in Internet Explorer, Edge, Chrome, Firefox, Safari, and every other browser. A properly generated ICO favicon ensures your website displays its icon consistently across all platforms and browser versions.
JPGをICOに変換する理由
Websites need favicons, and ICO is the only format guaranteed to work in every browser including legacy Internet Explorer versions. While you can use PNG favicons with a `<link>` tag, the classic `/favicon.ico` file at the site root is the fallback that browsers check automatically. Converting a JPG logo or image to ICO with multiple embedded sizes ensures your favicon looks sharp at every resolution.
Windows desktop applications, installers, and shortcuts require ICO format for their icons. If you are developing software, creating a desktop shortcut, or customizing folder icons on Windows, ICO is the only accepted format. The multi-size embedding means a single ICO file serves the 16x16 taskbar icon, the 32x32 desktop icon, and the 256x256 high-DPI icon without separate files.
主な活用例
- Create a website favicon from a logo or brand image
- Generate application icons for Windows desktop software
- Make custom folder icons for Windows file organization
- Produce installer icons for Windows setup packages (MSI/NSIS)
- Create desktop shortcut icons from company logos
- Generate browser tab icons that work in all browsers including legacy IE
仕組み
The converter resizes the source JPG to multiple standard icon sizes (16x16, 32x32, 48x48) and embeds them all within a single ICO container. For sizes up to 48x48, the image data is stored as BMP within the ICO. The resizing uses Lanczos3 resampling for the sharpest possible downscaling results. The source JPG should ideally be square — non-square images are center-cropped to a 1:1 aspect ratio before resizing.
品質とパフォーマンス
Quality depends heavily on the source image content. Photographs with fine detail lose clarity when shrunk to 16x16 or 32x32 pixels — icon design typically uses simple, bold shapes for this reason. For best results, start with a simple graphic or logo on a solid background. Complex photographs become unrecognizable at small icon sizes. The 256x256 size retains good detail and is used for Windows Vista+ large icon views.
デバイス互換性
| Device | JPG | ICO |
|---|---|---|
| Windows PC | Native | Native |
| macOS | Native | Partial |
| iPhone/iPad | Native | Partial |
| Android | Native | Partial |
| Linux | Partial | Partial |
| Web Browser | Native | No |
最良の結果を得るためのヒント
- 1Use a simple logo or graphic rather than a photograph for the best icon appearance
- 2Start with a square source image to avoid unwanted cropping
- 3For website favicons, also provide a 180x180 PNG for Apple Touch Icon
- 4Test your icon at 16x16 size — if it is not recognizable, simplify the design
- 5ICO is required for Windows applications and legacy browser favicon support
関連する変換
JPG to ICO conversion produces multi-resolution Windows icons and web favicons from your source image. For best results, use simple graphics with bold shapes rather than detailed photographs, since icons are viewed at very small sizes.
JPGとICOの比較
| 特徴 | JPG | ICO |
|---|---|---|
| 正式名称 | JPEG Image | Windows Icon |
| 拡張子 | .jpg | .ico |