What Is an Aspect Ratio Calculator?
An aspect ratio calculator determines the proportional relationship between width and height of an image, video, or screen. It helps designers and developers maintain correct proportions when resizing media for different displays and platforms.
How to Use This Aspect Ratio Calculator
- Enter the original width and height.
- Enter either the new width or new height.
- The calculator automatically computes the missing dimension to maintain the original ratio.
Key Concepts
Aspect ratio is expressed as width:height. Common ratios: 16:9 (widescreen, HD video), 4:3 (classic TV/monitors), 1:1 (square, social media), 9:16 (vertical mobile video), and 21:9 (ultrawide). The ratio is calculated by dividing both dimensions by their greatest common divisor (GCD). Maintaining aspect ratio prevents image distortion when scaling.
Width ÷ Height = Ratio, New Width = New Height × (Width ÷ Height)
Frequently Asked Questions
What aspect ratio should I use for YouTube videos?
YouTube recommends 16:9 (1920×1080 for Full HD, 3840×2160 for 4K). Vertical videos use 9:16. Non-standard ratios will have black bars (letterboxing or pillarboxing).
How do I calculate aspect ratio from pixel dimensions?
Divide both width and height by their GCD. For 1920×1080: GCD is 120, so 1920/120 : 1080/120 = 16:9.
What is the best ratio for social media images?
Instagram feed: 1:1 or 4:5. Instagram Stories: 9:16. Twitter/X: 16:9. Facebook: 1.91:1. LinkedIn: 1.91:1. Each platform has optimal dimensions for best display.