画像コンバーター




オンラインで画像のサイズを変更する

Upload an image, enter the new pixel dimensions, keep the aspect ratio if needed, and download a resized PNG, JPG, or WebP.

Resize previewまずは画像をアップロードしてください

Your resized image will appear here

Resize images for web, social, and documents

Exact pixel dimensions

Set the output width and height directly, or keep the original aspect ratio while changing one side.

PNG, JPG, or WebP output

Choose the format that fits your workflow, from transparent PNG to smaller WebP files.

Private local resizing

Your image stays in your browser. ImageConver does not upload the source file.

仕組み

  1. 1

    画像をアップロードする

    Choose a JPG, PNG, WebP, or other browser-readable image.

  2. 2

    寸法を入力してください

    Type the target width and height, then choose the output format.

  3. 3

    Download result

    Preview the resized image and save it to your device.

Best practices for image resizing

Resize images to the largest size you actually need. Smaller dimensions reduce file size and help pages load faster, while keeping aspect ratio prevents faces, products, and screenshots from looking stretched.

よくある質問

Can I keep the original aspect ratio?

Yes. Turn on keep aspect ratio, then changing width or height automatically updates the other side.

Does resizing upload my image?

いいえ。画像はブラウザーに残り、サイズ変更はローカルで実行されます。

Which output format should I use?

Use PNG for transparency, JPG for photos, and WebP when you want a smaller web-friendly file.

Resize Image Online last reviewed: Jun 27, 2026.