📐 Aspect Ratio Calculator

An aspect ratio is the proportional relationship between the width and height of an image, video, or screen. It is expressed as two numbers separated by a colon (e.g., 16:9), where the first number represents width and the second represents height. For example, a 16:9 ratio means the width is 16/9 (approximately 1.78) times the height. Aspect ratios are crucial in video production, photography, web design, and display manufacturing to ensure content displays correctly without stretching or cropping.

To calculate a 16:9 dimension, use these formulas:

• If you know the width: Height = Width × (9 ÷ 16) = Width × 0.5625
• If you know the height: Width = Height × (16 ÷ 9) = Height × 1.7778

For example, if your width is 1920 pixels, the matching 16:9 height would be 1920 × 0.5625 = 1080 pixels (Full HD). Our aspect ratio calculator above automates this instantly — just enter one dimension and select 16:9.

16:9 (widescreen) is wider and shorter — it has a width-to-height ratio of 1.78:1. It's the modern standard for HDTVs, YouTube videos, computer monitors, and streaming content.

4:3 (fullscreen) is more square-shaped with a ratio of 1.33:1. It was the standard for older CRT televisions, early computer monitors, and is still used by some iPads and digital cameras.

The shift from 4:3 to 16:9 happened because widescreen better matches human peripheral vision and provides a more immersive viewing experience.

• YouTube: 16:9 is the standard for regular videos (e.g., 1920×1080).
• YouTube Shorts: 9:16 vertical format (e.g., 1080×1920).
• Instagram Feed: 1:1 (square, 1080×1080), 4:5 (portrait, 1080×1350), or 1.91:1 (landscape).
• Instagram Stories/Reels: 9:16 (1080×1920).
• TikTok: 9:16 vertical (1080×1920) is the standard.
• Facebook: 16:9 or 1:1 for feed posts; 9:16 for Stories.

Use our calculator above to quickly find the right dimensions for any platform.

To find the aspect ratio from width and height, divide both numbers by their greatest common divisor (GCD). For example, for 1920×1080:

1. Find GCD of 1920 and 1080 → 120
2. Divide both: 1920 ÷ 120 = 16, 1080 ÷ 120 = 9
3. Result: 16:9

Our calculator does this automatically — simply enter your width and height values, and the simplified ratio appears instantly along with the diagonal measurement.

Absolutely! Our aspect ratio calculator supports any custom ratio. Simply type your desired ratio in the format W:H (e.g., "2.35:1", "3:2", "1.85:1", or even "16:10") into the custom ratio field. You can also use decimals like "1.78:1". The calculator will lock to that ratio and compute matching dimensions when you enter either width or height. It also handles ratio simplification — if you enter 20:15, it will simplify to 4:3.

The diagonal is the straight-line distance from one corner of a rectangle to the opposite corner, calculated using the Pythagorean theorem: √(width² + height²). It's important because screen sizes (TVs, monitors, phones) are universally measured diagonally. For example, a "24-inch monitor" refers to its diagonal screen size, not its width or height. Our calculator displays the diagonal in the same unit you use for width and height, helping you understand the overall scale of your dimensions.