Aspect Ratio Calculator

Find 16:9, 4:3, 1:1 image and screen dimensions.

Overview

Calculates widescreen display dimensions (16:9, 4:3, 21:9, 1:1) and resizes image/video pixel dimensions while preserving original visual proportions.

Formula & Calculation Method

New Height = (New Width × Original Height) / Original Width | Aspect Ratio = (Width / GCD) : (Height / GCD)

Uses the Greatest Common Divisor to express display aspect ratios in lowest canonical integer terms.

Worked Example: Resizing 1920×1080 Full HD Video to 1280px Width

Inputs: Original Width = 1920px | Original Height = 1080px | Target Width = 1280px

  • Find canonical ratio: GCD(1920, 1080) = 120; Ratio = 16:9 (1.7778)
  • Calculate proportional height: (1280 × 1080) / 1920 = (1280 × 9) / 16 = 720px
  • Resulting proportional resolution: 1280 × 720 pixels (720p HD)

Summary: Original = 1920×1080 (16:9) | Resized = 1280×720 (16:9) | Distortion = 0%

Common Use Cases

  • Video Production & Editing: Calculate custom render dimensions for 4K UHD, 1080p Full HD, and 720p exports.
  • Social Media Graphic Design: Format banner graphics to fit Instagram (1:1 and 4:5), YouTube thumbnails (16:9), and Stories (9:16).
  • Web Responsive Images: Set width and height attributes on HTML <img> tags to prevent Cumulative Layout Shift (CLS).

Frequently Asked Questions

What is the aspect ratio of 1920x1080?

1920x1080 has an aspect ratio of 16:9 (1.78:1), standard for widescreen video and monitors.

What aspect ratio is used for Instagram Reels and TikTok?

9:16 (vertical video, typically 1080×1920 pixels).

How does setting aspect ratio improve web performance?

Specifying aspect ratios on images lets browsers reserve space before images load, preventing Cumulative Layout Shift (CLS) layout jumps.

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