Aspect Ratio Calculator

1920x1080 has an aspect ratio of 16:9. This is the standard HD (High Definition) resolution used for most videos, TV broadcasts, computer monitors, and streaming content. It replaced the older 4:3 standard.

YouTube recommends 16:9 aspect ratio for standard videos. Use 1920x1080 for HD or 3840x2160 for 4K. For YouTube Shorts, use 9:16 vertical format at 1080x1920. YouTube will add letterboxing if your video doesn't match 16:9.

Instagram supports multiple ratios: 1:1 (1080x1080) for square posts, 4:5 (1080x1350) for portrait posts (this takes up the most screen space and is recommended), 1.91:1 (1080x608) for landscape, and 9:16 (1080x1920) for Stories and Reels.

Divide the width by the height, then simplify the fraction to its lowest terms. For example, 1920/1080 = 1.778. To find the ratio, calculate the Greatest Common Divisor (GCD) of both numbers. GCD(1920, 1080) = 120, so 1920/120 : 1080/120 = 16:9.

16:9 is widescreen (1.78:1 decimal), the modern standard for HD and 4K content. 4:3 (1.33:1 decimal) is the older standard definition format used for traditional CRT TVs and early computer monitors. 16:9 is 33% wider than 4:3 for the same height.

TikTok uses 9:16 vertical aspect ratio at 1080x1920 pixels. This full-screen vertical format is also used by Instagram Reels, YouTube Shorts, and Snapchat. Horizontal 16:9 videos are also supported but won't fill the screen.

To maintain aspect ratio when resizing, only change one dimension (width OR height), and calculate the other using the formula: new_height = new_width / aspect_ratio, or new_width = new_height * aspect_ratio. Our calculator does this automatically.

Cinema commonly uses 2.35:1 (CinemaScope/anamorphic) and 1.85:1 (theatrical flat). IMAX uses 1.43:1. These wider ratios create a more immersive, panoramic viewing experience. Many filmmakers add black bars to 16:9 content to achieve this cinematic look.