📐

Aspect Ratio Calculator

Resize dimensions while keeping the aspect ratio, with a visual preview

Change any field and the other side will be calculated automatically in proportion.

Scale preview

Instructions

アスペクト比計算機の使い方



機能概要


画像、動画、キャンバスのサイズを変更するとき、比率が崩れるのが一番の心配です。このツールは元の比率を保ったままもう片方のサイズを換算し、簡約した比率も表示します。

使用方法


  • 元の幅と高さを入力します(既定は 1920 × 1080)

  • 「新しい幅」または「新しい高さ」のどちらかを変更すると、もう片方が自動で計算されます

  • 上部のよく使う比率ボタン(16:9、4:3、1:1、21:9、9:16、3:2)をクリックして素早く適用することもできます

  • 結果エリアには簡約した比率、小数の比率、新しいサイズ、総ピクセル数が表示され、下には比率に応じて縮小した図が表示されます


  • 注意事項


  • 結果が小数の場合は四捨五入して小数点以下2桁で表示します。実際の書き出しは整数ピクセルを基準にしてください

  • 元のアスペクト比が特殊すぎる場合(例:1920:1081)は、簡約した比率を小数形式で表示します

  • すべてフロントエンドでの計算で、画像は一切アップロードされません
  • ❓ FAQ

    Why calculate the ratio before resizing?

    Stretching only the width or height distorts the image. Calculating the other side from the ratio keeps the image undistorted, which is exactly what the "keep aspect ratio" button does in image editing software.

    What are common 16:9 sizes?

    Common ones include 1920×1080, 1280×720, 2560×1440 and 3840×2160. Enter 1920 and 1080 as the original width and height, then set the new width to the value you want.

    Which ratio is used for vertical videos?

    The common vertical ratio for short videos is 9:16, for example 1080×1920 and 720×1280. Just click the 9:16 button to apply it.

    📝 Related Articles

    tool-tutorials

    How to Use a Countdown Timer: Complete Steps from Setting to Ringing

    This guide breaks down how to use a countdown timer into actionable steps, covering duration setting, start/pause, ring troubleshooting, phone mute and background restrictions, maximum duration limits, and the trade-offs between online and system timers, with developer API debugging points included—read it and you can start using it right away.

    tool-tutorials

    How to Use a Running Pace Calculator? Enter Distance and Time to Get Your Pace per Kilometer

    Want to know how long it takes you to run each kilometer? Just enter distance and total time to instantly get pace, speed, and split references. You can also troubleshoot common issues like wrong units, result deviations, and the calculator not opening on mobile—helping beginners quickly establish their own training baseline.

    tool-tutorials

    How to Use JS Formatter and Minifier: Beginner Step-by-Step Guide

    Use a browser-local JS formatter and minifier to restore a script minified into one line back to a readable structure, or remove whitespace and comments to reduce size—all without uploading code. This article provides step-by-step operations, error troubleshooting, API debugging, and large file handling methods—follow along and you can independently complete a formatting or minification task.

    tool-tutorials

    How to Use English Case Conversion: Beginner Step-by-Step Guide

    Paste English text into an online tool, choose the case mode, and complete the conversion with one click. This article provides the complete step-by-step operation, methods for mobile and large file handling, usage in API debugging scenarios, and troubleshooting ideas when conversion fails, helping you learn English case conversion in a few minutes and avoid common pitfalls such as abbreviations, line breaks, and mixed Chinese-English text.