BMP から WEBP へのオンライン変換

BMP ファイルを WEBP 形式に3ステップで簡単変換。

WEBP⌄

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⚙ オプション設定

Resize

Color Filter

DPI

dpi

Crop (px)

BMP vs WEBP：完全なフォーマットガイド

BMP

None

圧縮

WEBP

Lossy+Lossless

BMP

Only in 32-bit BMP via BITMAPV4/V5HEADER alpha channel — inconsistently supported by applications

透明度

WEBP

Full 8-bit alpha channel — same capability as PNG, with better compression efficiency

BMP

Not supported

アニメーション

WEBP

Supported — animated WebP stores multiple frames with per-frame timing data, offering vastly better quality and smaller files than animated GIF

BMP

1-bit monochrome to 32-bit RGBA — most common use is 24-bit (16.7 million colors)

色深度

WEBP

24-bit RGB + 8-bit alpha — 16.7 million colors with full alpha transparency

BMP

3 MB – 25 MB per image — a 1920×1080 24-bit BMP is approximately 5.9 MB

ファイルサイズ

WEBP

25–35% smaller than an equivalent-quality JPEG or PNG — typically 30–80 KB for standard web images

BMP

Technically supported by most browsers but virtually never used on the web due to enormous file sizes

ブラウザサポート

WEBP

Chrome 23+, Firefox 65+, Edge 18+, Safari 14+, Opera 12+. Not supported in Internet Explorer or Safari prior to iOS/macOS in 2020.

BMP

Legacy Windows apps

最適な用途

WEBP

Web images, modern apps

一般的なユースケース：BMP → WEBP

🌐 Modernizing legacy image archives⚡ Web performance optimization🛒 E-commerce image migration

⚠️Excellent for batch-modernizing old BMP image archives for web use. The file size reduction compared to original BMP is dramatic — typically 95–99% smaller.

Format

BMP

BMP (Device-Independent Bitmap) was introduced by Microsoft with the Windows 3.0 SDK in 1990 as the native raster format for Windows. It stores pixel data with zero compression, ensuring perfect repro…

長所

+Zero compression artifacts — the highest possible fidelity for raw storage

+Simple, well-documented format trivial to read/write programmatically

+Universal support across all Windows software and development tools

+Direct pixel data access with no decoding overhead

制限事項

−Extremely large files — a 1080p image is ~6 MB vs ~300 KB as JPG

−No practical web use — impractically large for any internet delivery

−Limited support outside Windows ecosystem

−No meaningful advantages over PNG for any modern use case

Legacy Windows applications that exclusively require BMP formatAutomated Windows image processing pipelines as an intermediate formatSystem resource files (wallpaper, specific application bitmaps)When absolute raw pixel fidelity is needed and file size is irrelevant

Format

WEBP

Google developed WebP and announced it in 2010 using technology from the VP8 video codec. Initial adoption was Chrome-only, but Firefox added support in 2019 and Apple's Safari 14 followed in 2020 — f…

長所

+25–34% smaller than JPEG/PNG at equal quality — direct page load improvement

+Both lossy and lossless compression modes in a single format

+Full alpha transparency like PNG at significantly smaller file sizes

+Animated WebP replaces GIF with full-color quality and dramatically smaller files

制限事項

−Not supported in Internet Explorer or Safari before iOS 14 / macOS Big Sur

−Print shops, Outlook, and Office apps don't accept WebP

−Limited native support in professional desktop imaging software

−Not practical for offline print workflows requiring Photoshop or Lightroom native support

Websites targeting modern browsers (Chrome, Firefox, Edge, Safari 14+)E-commerce and high-traffic sites where image performance impacts conversionsMobile-first apps where bandwidth and load time are criticalReplacing animated GIFs with higher-quality, much smaller animated alternatives

BMP から WEBP：知っておくべきこと

WebPはBMPが持っていないすべてを提供します：最新の圧縮（可逆と非可逆両方）、透明度サポート、大幅に小さいファイルサイズ。BMPをWebPに変換すると、目に見える品質損失なしに6MBの非圧縮ビットマップを200KB未満に削減できます。

なぜ BMP を WEBP に変換するのか？

📉

90〜97%のサイズ削減

WebPはBMPファイルを90〜97%圧縮し、ギガバイトのビットマップを管理可能なWebアセットに変換します。

Web対応形式

ブラウザはWebPをネイティブに表示します。BMPはプラグインなしにどのWebブラウザでもレンダリングできません。

🌐

🎨

可逆または非可逆

BMPの正確なピクセルデータを保持するために可逆WebPを、最大圧縮のために非可逆WebPを選択します。

即時読み込み

小さなWebPファイルはWebアプリで即座に読み込まれ、ユーザーエクスペリエンスを大幅に改善します。

⚡

BMP

ファイル拡張子.bmp
説明BMP (Bitmap) stores uncompressed bitmap digital images independently of the display device. Large file sizes but no quality loss.
関連プログラムMicrosoft Paint, Adobe Photoshop, GIMP, MS Photo Editor
開発者Microsoft
MIME タイプimage/bmp

WEBP

ファイル拡張子.webp
説明WebP provides superior lossless and lossy compression for images on the web. WebP images are typically 25-34% smaller than comparable JPEG or PNG files.
関連プログラムGoogle Chrome, Firefox, Adobe Photoshop (with plugin), GIMP
開発者Google
MIME タイプimage/webp