Aspect Ratio & Resolution Calculator
Calculate proportional dimensions, simplify resolutions into whole-number ratios via GCD, and preview 16:9, 9:16, 4:3, and 21:9 video layouts in real time.
CSS Property: aspect-ratio: 16 / 9;
How Aspect Ratio Calculations Work
An aspect ratio describes the proportional relationship between a display or image's width and height, written as W:H.
Height = (Width × Ratio Height) / Ratio Width
Width = (Height × Ratio Width) / Ratio Height
Simplifying Custom Resolutions
To convert raw pixel dimensions (such as 2560 × 1440) into a ratio, divide both the width and height by their Greatest Common Divisor (GCD):
GCD(2560, 1440) = 160.2560 / 160 = 16, and 1440 / 160 = 9. Thus, 2560 × 1440 simplifies to 16:9.
How to Use Aspect Ratio & Resolution Calculator (Step-by-Step)
Choose whether you want to calculate dimensions from a ratio, or find the ratio from pixel dimensions.
Enter your known width or height, or select a preset ratio (16:9, 4:3, 9:16, 21:9, 1:1).
Inspect the calculated dimensions and examine the real-time scaled visual preview box.
Applications
Common Use Cases
- Find the exact width or height required to maintain 16:9 or 9:16 proportions for video production.
- Calculate aspect ratios for responsive web images, hero banners, and CSS containers.
- Determine aspect ratios from non-standard camera dimensions or custom monitor resolutions.
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Understanding Aspect Ratios in Video, Photography & Web Design: 16:9 vs 4:3 vs 9:16
A complete guide to aspect ratios. Calculate width and height from ratios, understand standard 16:9, 9:16, 4:3, and 21:9 dimensions, and avoid black letterbox bars.
FAQ
Frequently Asked Questions
What is the formula for calculating aspect ratio dimensions?
Height = (Width × Ratio Height) / Ratio Width. Conversely, Width = (Height × Ratio Width) / Ratio Height.
What are the most common aspect ratios today?
16:9 is standard for YouTube, HDTV, and desktop monitors. 9:16 is standard for vertical mobile video (TikTok, Instagram Reels, YouTube Shorts). 4:3 is standard for classic photos, and 21:9 is ultrawide cinema.
How does the ratio simplifier work?
It uses the Euclidean greatest common divisor (GCD) algorithm to divide both width and height by their greatest common factor to find the simplest whole number ratio.
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