Aspect Ratio Calculator
Maintain aspect ratios when scaling images, videos, or designs. Enter any dimension to calculate the other.
Common ratios
Scale dimensions
px
px
16:9
Simplified ratio
1.778
Ratio as decimal
2.07 MP
Megapixels
1080p / Full HD
Common name
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Common aspect ratios reference
- 16:9 — HD and UHD video, YouTube, most monitors (1920×1080, 3840×2160)
- 4:3 — Legacy SD television, many tablets (1024×768)
- 1:1 — Square, Instagram posts, album art
- 21:9 — Ultrawide cinema displays, cinematic film
- 9:16 — Vertical video, mobile-first content (TikTok, Instagram Stories)
- 3:2 — DSLR cameras, 35mm film, many laptop screens
Frequently Asked Questions
What is aspect ratio?
An aspect ratio is the proportional relationship between an image's width and height, expressed as two numbers separated by a colon. For example, 16:9 means for every 16 units of width there are 9 units of height. It describes the shape of a frame, not its size.
Why is 16:9 so common?
16:9 (widescreen) became the standard for HD television, computer monitors, and online video platforms because it makes efficient use of the horizontal space in our peripheral vision. YouTube, Netflix, and most modern displays use 16:9.
What ratio is best for social media?
Different platforms prefer different ratios: Instagram square posts use 1:1, Instagram portrait stories use 9:16, Twitter/X recommended images use 16:9, Facebook covers use 16:9, and Pinterest favours 2:3 (portrait).