Aspect Ratio Calculator
Calculate the aspect ratio of any image or screen from its width and height. Find ratios, resize dimensions, compare common ratios, and get print sizes at any DPI.
Extended More scenarios, charts & detailed breakdown ▾
Professional Full parameters & maximum detail ▾
Ratio & Properties
Print Size at 300 DPI
Platform Crop
How to Use This Calculator
Enter your Width and Height in pixels to instantly see the aspect ratio in W:H form, the decimal ratio, and orientation. Use the Find Ratio tab for detailed stats including megapixels. The Resize tab lets you enter a target ratio and one dimension to calculate the other. The Common Ratios tab shows heights for popular ratios at your chosen width. The Professional tab adds print sizing at custom DPI and platform crop analysis.
Formula
GCD Method: Divide W and H by their greatest common divisor (GCD) to get the simplified ratio.
Resize: Other dimension = Known ÷ Ratio side × Other ratio side
Print size: Width (in) = Pixels ÷ DPI
Example
1920×1080: GCD(1920,1080) = 120 → 1920/120 : 1080/120 = 16:9 | Decimal = 1.7778 | Print at 300 DPI = 6.4 × 3.6 inches
Frequently Asked Questions
- Aspect ratio is the proportional relationship between width and height, expressed as W:H (e.g., 16:9). It defines the shape of an image or screen.
- 16:9 is the most common aspect ratio for modern displays, including HD and 4K TVs, monitors, and YouTube videos. 9:16 is standard for vertical mobile content (TikTok, Reels).
- Divide both width and height by their greatest common divisor (GCD). For example, 1920×1080: GCD = 120, so 1920/120 = 16 and 1080/120 = 9, giving 16:9.
- Use the Resize tab. Enter your target ratio and one known dimension (width or height), and the calculator provides the other dimension automatically.
- Instagram supports 1:1 (square), 4:5 (portrait, 1080×1350), and 16:9 (landscape). TikTok uses 9:16. YouTube thumbnails use 16:9 (1280×720).