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Aspect Ratio Calculator

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Calculate proportional image and video dimensions, find common screen aspect ratios (16:9, 4:3, 1:1, 21:9), and scale resolutions without distortion.

100% In-Browser Privacy
Zero Server Uploads

Standard Aspect Ratio Presets

:
Width
×
Height
1920 × 1080(16:9)

Who Is Aspect Ratio Calculator Built For?

Video editors and motion designers scaling video frames between 16:9 widescreen and 9:16 vertical shorts
Web developers and UI designers sizing responsive CSS aspect-ratio containers and canvas elements
Photographers resizing photos to match standard print ratios (4:6, 5:7, 8:10)

Key Benefits & Core Capabilities

Proportional Dimension Scaling

Enter any width or height to automatically compute the corresponding proportional dimension.

Standard Preset Ratios

One-click presets for 16:9 (HD/4K), 9:16 (TikTok/Reels), 4:3 (Classic), 1:1 (Square), 21:9 (Ultrawide), and 3:2 (DSLR).

Greatest Common Divisor (GCD) Ratio Finder

Enter arbitrary pixel dimensions (e.g. 2560 × 1080) to find the exact simplified aspect ratio (64:27).

Visual Aspect Ratio Box Preview

Interactive visual preview box updates proportionally as you adjust dimensions.

Step-by-Step Guide: How to Use Aspect Ratio Calculator

  1. 1
    Choose a Preset or Enter Custom RatioSelect a standard preset (such as 16:9, 4:3, 1:1, or 9:16) or input your custom ratio width and height.
  2. 2
    Input DimensionEnter your desired width or height in pixels. The opposite dimension calculates automatically while keeping proportions locked.
  3. 3
    Copy or Use DimensionsCopy the computed dimensions with one click for use in your CSS, image editor, or video rendering software.

How It Works & Technical Architecture

The Aspect Ratio Calculator calculates proportional dimensions using the formula: New Height = (Original Height / Original Width) × New Width.

To find simplified aspect ratios from pixel dimensions, it applies the Euclidean algorithm to find the Greatest Common Divisor (GCD(W, H)) and divides both dimensions by that factor.

Calculations execute in real time in browser JavaScript.

Practical Use Cases & Applications

Social Media Video Sizing

Resize 1920×1080 horizontal YouTube videos to 1080×1920 vertical format for Instagram Reels and TikTok.

Responsive Web Design

Calculate padding-top percentage or aspect-ratio CSS values for responsive video embeds.

Photo Print Dimension Matching

Check if a 6000×4000 camera photo fits onto an 8×10 inch print without cropping.

Display Screen Resolution Check

Find the aspect ratio of uncommon ultrawide monitors and mobile device displays.

Supported Formats & Input Options

Width & Height (Pixels, Inches, CM)Preset Ratios (16:9, 4:3, 1:1, 9:16, 21:9, 3:2)

Frequently Asked Questions

What is the aspect ratio for 1920x1080 and 3840x2160?

Both 1920x1080 (Full HD) and 3840x2160 (4K UHD) have a standard 16:9 widescreen aspect ratio.

What aspect ratio is used for Instagram Reels and TikTok?

Vertical social media videos use a 9:16 aspect ratio (most commonly 1080x1920 pixels).

How do I resize an image without stretching or distorting it?

Keep the aspect ratio locked in the calculator, enter your new desired width, and use the calculated height to scale proportionally.

Are my dimensions sent to any server?

No. All calculations run strictly inside your local browser.

Can I find the aspect ratio of custom screen resolutions?

Yes. Enter your custom width and height, and Softnag will compute the simplified ratio and decimal multiplier.

What is the formula for calculating an aspect ratio?

Aspect ratio is the proportional relationship between width (W) and height (H), expressed as W:H. To scale a height with a locked ratio: Height = (Width × Ratio_H) / Ratio_W.

What is the standard aspect ratio for YouTube videos and 4K screens?

The standard widescreen display aspect ratio is 16:9 (e.g., 1920×1080 for 1080p Full HD, 3840×2160 for 4K UHD).