Aspect ratio calculator
Original size
Detected aspect ratio
16:9
Decimal 1.7778
New size
Live preview
The box shows the proportions of the new size.
Presets
Common video and display resolutions
| Name | Dimensions | Ratio | Action |
|---|---|---|---|
| 4K UHD | 3840 x 2160 | 16:9 | |
| 2K QHD | 2560 x 1440 | 16:9 | |
| 1080p Full HD | 1920 x 1080 | 16:9 | |
| 720p HD | 1280 x 720 | 16:9 | |
| 480p SD | 854 x 480 | 16:9 |
Why use EZRatioCalculator
- Free aspect ratio calculator that reduces any size to its simplest ratio, such as 16:9, 4:3 or 1:1.
- Type a new width to get the height, or a new height to get the width, with the ratio locked.
- One-click presets for YouTube, TikTok, Instagram posts, Reels and ultrawide screens.
- Live preview box and a reference table of 4K, 2K, 1080p and 720p resolutions.
- 100% client-side: nothing is uploaded and no sign-up is needed.
How to calculate aspect ratio
An aspect ratio describes the proportion between width and height. To find it, divide both numbers by their greatest common divisor (GCD). For 1920 x 1080 the GCD is 120, so the ratio is 16:9.
Resize without distortion
To scale an image, multiply the new width by the original height and divide by the original width. The result is the new height: 1280 x 1080 / 1920 = 720. EZRatioCalculator does this for you whenever the ratio is locked, in both directions.
16:9 vs 9:16
The proportions are the same, but 16:9 is landscape for YouTube, TVs and monitors, while 9:16 is portrait for TikTok, Reels, Stories and Shorts.
Social media sizes
Instagram: 1080 x 1080 (1:1), 1080 x 1350 (4:5), 1080 x 1920 (9:16) for Stories and Reels. YouTube: 1920 x 1080 video and 1280 x 720 thumbnails.
Frequently asked questions
How to calculate aspect ratio?
Divide the width and height by their GCD. For 1920 x 1080 the GCD is 120, so 1920/120 : 1080/120 gives 16:9. To resize, multiply the new width by original height and divide by original width to get the new height.
What is the difference between 16:9 and 9:16?
Both have the same proportions, but 16:9 is landscape (wider than tall) and is used for YouTube, TVs and monitors. 9:16 is portrait (taller than wide) and is used for TikTok, Instagram Reels, Stories and YouTube Shorts.
What are standard resolutions for Instagram and YouTube?
Instagram square posts are 1080 x 1080 (1:1), portrait posts 1080 x 1350 (4:5), and Stories and Reels 1080 x 1920 (9:16). YouTube videos are commonly 1920 x 1080 (16:9) or 3840 x 2160 for 4K, and thumbnails are 1280 x 720.
How do I resize an image without distorting it?
Keep the aspect ratio locked and change only one dimension. The other dimension is calculated automatically so the proportions stay identical.
Is EZRatioCalculator free and private?
Yes. EZRatioCalculator is free and runs entirely in your browser. The numbers you type are never sent to a server.