Aspect Ratio Calculator

Calculate aspect ratios from pixel dimensions or find the missing dimension from a known ratio. Includes presets for video, social media, and devices.

Calculate aspect ratios from pixel dimensions, or find the missing dimension from a known aspect ratio. Includes presets for video, social media, and devices.

Common Aspect Ratios
Preset Resolutions
The aspect ratio describes the proportional relationship between width and height. Common ratios include 16:9 (widescreen), 4:3 (classic), and 1:1 (square). All calculations happen instantly in your browser.

How to Use This Tool

  1. 1

    Choose your mode

    Select 'Dimensions → Ratio' to find the ratio from pixel values, or 'Ratio → Dimensions' to calculate the missing dimension.

  2. 2

    Enter your values

    Input width and height in pixels, or enter an aspect ratio and one known dimension. Results update instantly as you type.

  3. 3

    Use presets

    Click common aspect ratios (16:9, 4:3, 1:1) or preset resolutions (1080p, 4K, Instagram) to auto-fill values.

  4. 4

    Copy the result

    Click 'Copy' to copy the calculated ratio or resolution to your clipboard for use in your projects.

Frequently Asked Questions

What is an aspect ratio?
An aspect ratio is the proportional relationship between width and height of an image or screen. For example, 16:9 means for every 16 units of width, there are 9 units of height.
What's the best aspect ratio for YouTube?
YouTube uses 16:9 as the standard aspect ratio. Upload videos at 1920×1080 (Full HD) or 3840×2160 (4K) for best results.
How do I find the missing dimension?
Switch to 'Ratio → Dimensions' mode, enter your desired aspect ratio (e.g., 16:9), select whether you know the width or height, and enter the known value. The tool calculates the other dimension.
What aspect ratio should I use for Instagram?
Instagram supports 1:1 (square, 1080×1080), 4:5 (portrait, 1080×1350), and 1.91:1 (landscape, 1080×566). Stories and Reels use 9:16 (1080×1920).