Aspect Ratio Calculator

How to Use

1. Click a preset button (16:9, 4:3, etc.) to fill in a common ratio, or enter custom width and height.
2. Click 'Calculate Ratio' to see the simplified aspect ratio, orientation, decimal value, and equivalent standard sizes.
3. Use the Resize section to calculate new dimensions: enter the original size, then either the new width OR height, and the other will be computed automatically.

Features

• Instant simplified ratio calculation using GCD algorithm.
• Visual preview rectangle showing the shape of the ratio.
• Common size equivalents for 480p, 720p, 1080p, 4K and more.
• Resize calculator: enter one dimension, get the other locked to ratio.
• One-click presets for 16:9, 4:3, 1:1, 9:16, 21:9, 3:2, and more.
• No server required — pure browser math.

Use Cases

• Web developers and designers sizing images for responsive layouts.
• Video creators checking that footage matches YouTube, Instagram, or TikTok requirements.
• Photographers resizing photos for prints while avoiding crop distortion.
• Game developers setting up viewport and texture dimensions.
• Marketing teams scaling banner ads to different size requirements.

FAQ

What is an aspect ratio?

An aspect ratio is the proportional relationship between width and height expressed as W:H. 1920×1080 has a 16:9 ratio — it's 16 units wide for every 9 units tall.

What aspect ratio should I use for YouTube videos?

YouTube recommends 16:9. For Shorts, use 9:16. Common resolutions: 1280×720 (720p), 1920×1080 (1080p), 3840×2160 (4K).

How do I resize without distortion?

Enter the original width and height in the Resize section, then enter only the desired new width (or height). The tool calculates the other dimension proportionally so the ratio stays the same.

What is the 21:9 ultrawide format?

21:9 is the ultra-wide aspect ratio used in cinematic films and some monitors. Actual implementations vary — a common resolution is 2560×1080 or 3440×1440.