Web & SEO

Aspect Ratio Calculator — Free 2026

Enter width and height to find the ratio, or select a preset ratio to calculate dimensions. Bidirectional and instant.

Width (px)

Height (px)

Preset Ratio

Visual Preview

Results

16:9

Aspect Ratio

1920

Width (px)

1080

Height (px)

1.778

Decimal Ratio

How It Works

Enter dimensions
Or select a ratio
Read the results

Understanding Aspect Ratios

Aspect ratio describes the proportional relationship between the width and height of a visual element. Whether you are resizing images for a website, setting up a video project, or designing social media content, understanding aspect ratios ensures your visuals display correctly without unwanted cropping or stretching. This calculator makes it easy to convert between dimensions and ratios in both directions.

Common Aspect Ratios and Their Uses

16:9 is the universal widescreen standard, used by YouTube, Netflix, HDTVs, and most computer monitors. 4:3 was the traditional TV and computer monitor ratio, still used on iPads and some presentations. 1:1 (square) is popular for Instagram feed posts and profile pictures. 9:16 (vertical) dominates mobile-first platforms like Instagram Stories, TikTok, and YouTube Shorts. 21:9 is the ultrawide cinema format used in movie theaters and gaming monitors.

Aspect Ratios for Social Media

Each social platform has preferred dimensions: Facebook recommends 1200x630 (roughly 1.91:1) for link previews, Instagram supports 1080x1080 (1:1) and 1080x1350 (4:5), Twitter recommends 1200x675 (16:9) for images, and LinkedIn prefers 1200x627. Using the correct ratio prevents cropping and ensures maximum visual impact. For resizing images to these dimensions, try our image resizer, or use the percentage calculator for scaling proportionally.

How Aspect Ratio Is Calculated

The aspect ratio is found by dividing both the width and height by their greatest common divisor (GCD). For example, 1920 / 120 = 16 and 1080 / 120 = 9, giving 16:9. The GCD is calculated using the Euclidean algorithm. When you need to find dimensions from a ratio, multiply the ratio components by a scale factor: for 16:9 at 1280px wide, the height is 1280 * (9/16) = 720px.

Frequently Asked Questions

What is aspect ratio?

Aspect ratio is the proportional relationship between width and height of an image, video, or screen. It is expressed as two numbers separated by a colon, such as 16:9 or 4:3. The ratio remains constant regardless of the actual pixel dimensions.

What is the most common aspect ratio for video?

16:9 (widescreen) is the standard aspect ratio for YouTube, most streaming services, HDTVs, and modern monitors. Common resolutions in 16:9 include 1920x1080 (Full HD), 2560x1440 (QHD), and 3840x2160 (4K UHD).

What aspect ratio is best for Instagram?

Instagram supports multiple ratios: 1:1 (square, 1080x1080) for feed posts, 4:5 (portrait, 1080x1350) for maximum feed visibility, and 9:16 (vertical, 1080x1920) for Stories and Reels. The 4:5 ratio takes up the most screen space in the feed.

How do I calculate aspect ratio from dimensions?

Divide both width and height by their greatest common divisor (GCD). For example, 1920 and 1080 both divide by 120, giving 16:9. This calculator does it automatically — just enter your width and height to see the simplified ratio.