アスペクト比計算機

無料のアスペクト比計算機。幅と高さから比率を計算し、いずれかの軸をリサイズして同じ比率を維持します。画像、動画、デザインに。

Runs in your browserUpdated Apr 26, 2026

Original width

Original height

Resize to fit a new width

Ratio

16:9

Decimal

1.7778

よくある質問

›How do I calculate aspect ratio?

Divide width by height, then simplify the resulting fraction. We do it for you and show common-name matches (16:9, 4:3, etc.).

›Can I resize keeping the ratio?

Yes — enter a new width and the height auto-adjusts (or vice versa) to maintain the original ratio.

›What's the most common video ratio?

16:9 for landscape (HD/4K video, YouTube), 9:16 for vertical (TikTok, Instagram Reels), 1:1 for square (Instagram feed).

›Is the calculator free?

Yes — fully free, no signup.