Design & Freelance

Aspect Ratio Calculator

Calculate proportional dimensions, simplify aspect ratios with GCD, and generate responsive CSS aspect-ratio properties.

🔒 100% Private In-Browser Geometry: Instant precision scaling for video editing, responsive web development, and social media image sizing.
Simplified Aspect Ratio
16:9(1.778:1 decimal)

CSS Rule: aspect-ratio: 16 / 9;

Padding Fallback: 56.25%

1. Original Dimensions (or Base Ratio)

Defines the locked proportional ratio baseline

2. Target Scaled Dimensions

Changing either value automatically calculates the other

Interactive Proportion Preview
16:91280 × 720 px
Standard Screen & Video Presets
CSS aspect-ratio
aspect-ratio: 16 / 9;
Padding-Top Trick Fallback
/* Legacy responsive container */
.aspect-box {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
}
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What is Aspect Ratio Calculator?

Maintaining correct aspect ratios prevents visual layout distortion and Cumulative Layout Shift (CLS) when resizing images, videos, and responsive containers. Our Aspect Ratio Calculator simplifies dimensions using Euclidean Greatest Common Divisor (GCD) math, solves missing widths/heights, and outputs modern CSS aspect-ratio declarations.

Designed for accuracy, speed, and privacy, this tool runs entirely on your local device with zero network latency.

How to Use the Aspect Ratio Calculator

  1. 1
    Enter your original container Width and Height (e.g., 1920 x 1080) to compute the simplified ratio (16:9).
  2. 2
    Select a common preset (16:9, 4:3, 1:1, 21:9, 9:16, 3:2, Golden Ratio) to populate dimensions instantly.
  3. 3
    Type a new target Width or Height to solve for the missing proportional dimension in real time.
  4. 4
    Copy the calculated pixel dimensions, simplified fraction ratio, or modern CSS aspect-ratio declaration.

Formula & Calculation Logic

Applies cross-multiplication for dimension scaling and the Euclidean algorithm to find the Greatest Common Divisor (GCD) for exact integer ratio reduction.

Proportional Equation: NewHeight = (OriginalHeight * NewWidth) / OriginalWidth; Simplified Ratio = (W / GCD) : (H / GCD)

Aspect Ratio Calculator Frequently Asked Questions

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