Aspect Ratio Calculator
Calculate proportional image and video dimensions while maintaining your chosen aspect ratio. Supports common presets like 16:9, 4:3, and custom ratios.
Aspect Ratio Calculator
Calculate dimensions while maintaining standard aspect ratios.
Original Ratio
New Dimensions
All processing happens locally in your browser — nothing is stored or sent to any server.
How to Use the Aspect Ratio Calculator
- Enter the original width and height or pick a preset ratio from the buttons.
- Lock the ratio to keep it fixed while adjusting dimensions.
- Enter a new width or height — the proportional counterpart is calculated automatically.
About Aspect Ratio Calculation
An aspect ratio describes the proportional relationship between a width and height. Keeping this ratio consistent prevents distortion when scaling images, videos, or UI elements. A 16:9 image resized to 16:9 dimensions always looks correct; the same image forced into 4:3 will appear stretched or compressed.
Common use cases include: resizing images for responsive web layouts without distortion, calculating export dimensions for video platforms (YouTube, TikTok, Instagram each have different standards), planning CSS grid layouts with consistent proportions, and preparing print materials where exact proportional dimensions matter.
The calculator uses the formula: new height = (new width / original width) × original height. All calculations run locally in your browser.
Frequently Asked Questions
What aspect ratio is 1920×1080? ▼
1920×1080 has a 16:9 aspect ratio, the most common standard for HD and Full HD monitors, YouTube videos, and most modern displays.
What is the 4:3 ratio used for? ▼
4:3 was the standard for older CRT monitors and televisions, and is still used in some photography formats and classic presentation slides (PowerPoint default before 2013).
Can I enter custom aspect ratios? ▼
Yes. Enter any width and height values as your source dimensions, and the calculator will maintain that exact ratio when calculating the proportional counterpart.
What aspect ratio does Instagram use? ▼
Instagram supports multiple ratios: 1:1 (square posts), 4:5 (portrait posts), and 16:9 (landscape posts and Reels). The 4:5 ratio at 1080×1350 pixels is the standard for vertical feed posts.
What is the difference between 16:9 and 16:10? ▼
16:10 (1920×1200, 2560×1600) provides slightly more vertical space than 16:9, making it popular for productivity-focused monitors and older MacBooks. Most consumer monitors use 16:9.
How do I calculate aspect ratio from resolution? ▼
Divide both dimensions by their greatest common divisor (GCD). For 1280×720: GCD is 80, so 1280÷80=16 and 720÷80=9, giving 16:9. This calculator does the GCD math for you.
What is a cinematic aspect ratio? ▼
2.39:1 (also written as 2.40:1) is the standard widescreen cinema format, creating the wide black bars you see in movie letterboxing. 2.35:1 is the classic CinemaScope ratio.
Is everything processed locally? ▼
Yes. All calculations run in your browser with JavaScript. No data is sent to any server.