Aspect Ratio Calculator
Calculate and convert aspect ratios for images and videos.
Original Dimensions
Resize Dimensions
Common Resolutions
About this tool
Calculate aspect ratios, resize dimensions while maintaining proportions, and convert between common ratios like 16:9, 4:3, and 1:1. Essential for designers working with images, videos, and responsive layouts.
Features
- Calculate aspect ratios from width and height
- Resize dimensions while maintaining proportions
- Common presets for 16:9, 4:3, 1:1, and more
- Perfect for responsive design and media sizing
How to Use
- Enter the width and height of your image or video
- View the calculated aspect ratio
- Enter a new width or height to resize proportionally
- Use preset ratios for common media formats
Frequently Asked Questions
Why is 16:9 the standard for video?
HDTV and YouTube settled on it in the 2000s as a compromise between 4:3 television (too square) and cinematic 2.35:1 (too wide for home viewing). Every modern platform — phones held sideways, laptops, TVs, Twitch — is built around 16:9. Shooting 9:16 vertical is a recent break for mobile-native platforms.
What aspect ratio should I use for Instagram?
Instagram accepts multiple, but three are worth remembering: 1:1 square for the feed (still works everywhere), 4:5 portrait for feed (maximises screen space), 9:16 for Stories and Reels. Post a 4:5 on the feed to take more vertical real estate than a 1:1 neighbour.
Does cropping to an aspect ratio lose image quality?
Cropping itself doesn't — you're just discarding pixels. Resizing (scaling up or down) is what loses information. If your original is larger than the target, crop then scale down, which preserves detail. Never scale up and then crop.
What's the difference between aspect ratio and resolution?
Aspect ratio is a shape (16:9, 4:3). Resolution is a pixel count at that shape (1920×1080, 3840×2160). A 16:9 video at 1080p and a 16:9 video at 4K have the same shape and display behaviour — 4K just has four times the pixels.
Why is 2.39:1 called "widescreen cinema"?
It's the anamorphic 35mm format: squeezed onto a 4:3 frame during shooting, then stretched back during projection. Hollywood's 2:35 (older) and 2.39:1 (current) are both called "widescreen". Trying to fit that ratio on a 16:9 TV is why you get letterboxing.