How do I crop an image to exact dimensions?

Upload your image, then enter the X offset, Y offset, width, and height in pixels. The X and Y values set the starting point of the crop from the top-left corner. Width and height define the size of the cropped area. Click Crop to see the result and download it.

Does cropping an image reduce its quality?

No, cropping does not reduce image quality. It simply extracts a portion of the original image. This tool outputs the cropped area as a PNG file, which is a lossless format that preserves the original pixel data within the selected region.

Can I crop images without uploading them to a server?

Yes, this tool processes images entirely in your browser using the HTML5 Canvas API. Your images never leave your device. No server communication occurs, making it completely private and secure for sensitive or confidential images.

Image Cropper

ブラウザ内で画像をトリミング。座標とサイズを指定して正確に切り抜き。

How to Use the Image Cropper

This free online image cropper lets you trim and cut images directly in your browser using the HTML5 Canvas API. Upload any image, specify the crop region using exact pixel coordinates (X offset, Y offset, width, and height), then download the cropped result as a PNG file. All processing happens entirely client-side, meaning your images never leave your device, ensuring complete privacy and instant results regardless of internet speed.

Setting the Crop Area

The crop area is defined by four values: X and Y offsets specify the top-left corner of the crop region relative to the original image, while width and height define the size of the area to extract. By default, the crop area covers the entire image. Adjust these values to select the exact portion you need. The tool validates that the crop area stays within the image boundaries to prevent errors.

Common Cropping Scenarios

Image cropping is useful for removing unwanted borders, focusing on specific subjects, creating profile pictures from larger photos, and preparing images for specific aspect ratios. For social media thumbnails, crop to square dimensions. For website hero images, use wide landscape crops. Product photography often benefits from tight cropping around the subject to remove distracting backgrounds and create a clean, professional look.

Tips for Best Results

Note the original image dimensions shown after upload, then calculate your desired crop coordinates accordingly. For centering a crop, set X to (imageWidth - cropWidth) / 2 and Y to (imageHeight - cropHeight) / 2. The output is PNG format which preserves quality without compression artifacts. If you need to resize the cropped image afterwards, use the Image Resizer tool for further dimension adjustments.

Image Cropperの使い方

このツールはブラウザ上で動作する無料の画像トリミングツールです。画像をアップロードし、X/Yオフセットと幅・高さをピクセル単位で指定して正確にトリミングできます。すべての処理はクライアントサイドで完結し、画像がサーバーに送信されることはありません。トリミング結果はPNG形式でダウンロード可能です。

よくある落とし穴と対処 / Common Pitfalls

落とし穴 / Pitfall	問題 / Problem	対処 / Fix
SNSごとに比率が違う Each platform wants a different ratio	正方形(1:1)・縦長(4:5, 9:16)・横長(1.91:1)が混在 Square, portrait and landscape ratios coexist	投稿先の比率を先に決めてからトリミング。比率計算はAspect Ratio Calculator Decide the target ratio first
サムネイルで重要部分が見切れる Subject cut off in thumbnails	一覧表示はさらに中央クロップされることがある Lists may center-crop again	被写体を中央寄りに配置し、端に重要要素を置かない Keep key content near the center
切り抜き後の解像度不足 Cropped result too small	小さい領域の切り出しは実質的な拡大表示になりぼやける Small crops get upscaled and blur	必要な表示サイズ以上の領域を切り出す Crop at least the display resolution
「見えない」だけで残っている Hidden but not removed	一部アプリの「クロップ」は表示範囲の記録だけで元データが残る場合がある Some apps store crop as metadata, keeping the full image	本ツールはピクセル自体を切り出すため、範囲外のデータは残らない This tool re-renders pixels; nothing outside survives

用途別の定番比率 / Common Ratios

プロフィールアイコン: 1:1 (512x512)
OGP / リンクカード:   1.91:1 (1200x630)
YouTubeサムネ:        16:9 (1280x720)
Instagramフィード:    1:1 / 4:5
ストーリー・Shorts:   9:16 (1080x1920)

Why browser-only?

Cropping is often about removing something private — a face, an address bar, a document edge. Doing that on a server means the uncropped original gets uploaded first. This tool crops with the Canvas API entirely in your browser: the full image never leaves your device, and the discarded region is truly gone from the output. Zero requests in the DevTools Network tab.

トリミングの目的は「写したくない部分を消す」ことが多いもの。本ツールは切り抜き前の元画像がアップロードされることはなく、範囲外のピクセルは出力に一切残りません。