Image Aspect Ratio Calculator
The Image Aspect Ratio Calculator determines the aspect ratio of any image from its pixel width and height. Calculate proportional resize dimensions, compare standard photo sizes, and ensure your images maintain the correct proportions across different platforms.
🕐 Recent Calculations
What is Image Aspect Ratio?
Image aspect ratio is the proportional relationship between an image's width and height measured in pixels. A 4000 × 3000 pixel image has a 4:3 aspect ratio. Knowing the aspect ratio is essential for cropping, resizing, and formatting images for web, print, and social media without distortion.
Standard image aspect ratios include 3:2 (DSLR cameras), 4:3 (smartphone cameras, micro four-thirds), 16:9 (screenshots, wallpapers), 1:1 (Instagram posts), and 5:4 (8×10 prints). The Image Aspect Ratio Calculator helps photographers and designers maintain consistency.
使用される計算公式・方程式
この計算ツールは5つの主要な公式を使用しています：
1 Image Aspect Ratio ▼
A 6000 × 4000 image: GCD = 2000, so ratio = 3 : 2. This is the standard DSLR sensor ratio.
2 Proportional Resize (New Height) ▼
Resizing a 4000×3000 image to 1200px wide: New Height = 1200 × (3000/4000) = 900 pixels.
3 Megapixel Calculation ▼
A 6000 × 4000 image = 24,000,000 pixels = 24 megapixels.
比率計算ツールの使い方
この比率計算ツールは、以下の3ステップで簡単にご利用いただけます：
数値を入力
入力欄に既知の比率の値を入力します。求めたい未知数の入力欄は空欄のままにしておきます。
モードを選択
比率モード（解く、簡素化、スケーリング）を選択します。各モードで異なる計算式が適用されます。
結果を確認
計算するボタンを押します。結果画面に答えと、視覚的な比率バー、円グラフ、詳細なステップバイステップの解決プロセスが表示されます。
実例問題と段階的な解説
本比率計算ツールを使って、以下の3つの例題をステップバイステップで解決するプロセスです：
入力 1 Find aspect ratio of a 5184 × 3456 image
入力 2 Resize a 4032 × 3024 photo to 800px wide
入力 3 Calculate megapixels of 7680 × 4320
よくある質問 (FAQ)
What aspect ratio do DSLR cameras use? ▼
Most DSLR cameras use a 3:2 aspect ratio, which matches the 35mm film format. Common resolutions include 6000×4000 (24MP), 6720×4480 (30MP), and 8256×5504 (45MP).
How do I find the aspect ratio of an image on my computer? ▼
Right-click the image → Properties → Details tab. Note the width and height in pixels. Divide both by their GCD to get the simplified aspect ratio. For example, 3840×2160 simplifies to 16:9.
What is the best image aspect ratio for Instagram? ▼
Instagram supports 1:1 (square, 1080×1080), 4:5 (portrait, 1080×1350), and 1.91:1 (landscape, 1080×566). The 4:5 portrait format takes up the most screen space in feeds.
Can I change an image's aspect ratio without cropping? ▼
Changing aspect ratio without cropping requires adding padding (letterboxing) or stretching the image. Stretching distorts the content. Adding colored bars preserves quality but changes the visual composition.
What resolution should I use for printing? ▼
For high-quality prints, use 300 DPI. An 8×10 inch print needs 2400×3000 pixels (4:5 ratio). A 16×20 inch poster needs 4800×6000 pixels.