Definition
Aspect ratio is the proportional relationship between the width and height of a video frame or image, expressed as two numbers separated by a colon (e.g., 16:9, 4:3, 9:16). The 16:9 widescreen ratio is the standard for YouTube, television, and most digital displays. The 9:16 vertical ratio is the standard for TikTok, Instagram Reels, and YouTube Shorts. The 4:3 ratio was the television standard before widescreen adoption. Choosing the correct aspect ratio for each platform is essential for proper display without cropping, letterboxing, or pillarboxing.