Aspect Ratio Calculator
Calculate missing dimensions, simplify ratios, and convert between aspect ratios for images, videos, and screens.
Find Missing Dimension
Enter the original width and height, then enter one new dimension to calculate the other while preserving the ratio.
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Find & Simplify Ratio from Dimensions
Enter width and height to find the simplified aspect ratio and decimal ratio.
Convert Ratio to Dimensions
Enter an aspect ratio (e.g. 16:9) and one dimension to find the other.
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Common Aspect Ratio Presets
| Ratio | Common Name | Common Resolutions | Use Case | |
|---|---|---|---|---|
| 16:9 | Widescreen HD | 1920×1080, 2560×1440, 3840×2160 | TV, YouTube, most monitors | |
| 4:3 | Standard / Fullscreen | 1024×768, 1600×1200 | Old TVs, presentations | |
| 1:1 | Square | 1080×1080 | Instagram posts, album art | |
| 21:9 | Ultrawide | 2560×1080, 3440×1440 | Ultrawide monitors, cinema | |
| 9:16 | Portrait / Vertical | 1080×1920 | TikTok, Instagram Reels, Stories | |
| 16:10 | Widescreen (laptop) | 1920×1200, 2560×1600 | MacBook, professional laptops | |
| 4:5 | Portrait | 1080×1350 | Instagram portrait posts | |
| 2.35:1 | CinemaScope | 2350×1000 | Widescreen cinema | |
| 1.85:1 | Academy Flat | 1850×1000 | Standard cinema projection | |
| 3:2 | DSLR / 35mm film | 6000×4000, 3000×2000 | Photography, 35mm film |
Quick Reference
Scale formula:
New H = (New W / Old W) × Old H New W = (New H / Old H) × Old W
Simplify a ratio:
Divide both numbers by their Greatest Common Divisor (GCD).
Decimal ratio:
Divide width by height: 1920 ÷ 1080 = 1.78 (= 16:9)
Social Media Cheat Sheet:
- YouTube thumbnail: 16:9
- Instagram square: 1:1
- Instagram portrait: 4:5
- Instagram landscape: 1.91:1
- TikTok / Reels: 9:16
- Facebook cover: ~2.7:1
- Twitter/X header: 3:1
- LinkedIn post: 1.91:1
- Pinterest pin: 2:3
- LinkedIn cover: 4:1
Frequently Asked Questions
An aspect ratio is the proportional relationship between the width and height of a rectangle, typically expressed as W:H (e.g. 16:9 or 4:3). It describes the shape of an image or screen without specifying actual pixel dimensions. The same aspect ratio can apply to many different resolutions — for example, both 1920×1080 and 1280×720 have a 16:9 ratio.
16:9 (1.78:1) is the standard widescreen ratio used for most modern TV broadcasts, YouTube, Netflix, and HD/4K monitors. Before widescreen became standard, 4:3 (1.33:1) was used for traditional television and early computer monitors. For cinema, common ratios include 2.35:1 (CinemaScope) and 1.85:1.
If you know the original width and height and want to resize to a new width, the new height = (new width ÷ original width) × original height. Conversely, for a new height, new width = (new height ÷ original height) × original width. This calculator does this automatically for you.
Different platforms use different ratios. Instagram square posts use 1:1 (1080×1080 px); Instagram landscape is 1.91:1 (1080×566 px); Instagram portrait is 4:5 (1080×1350 px). Facebook cover photos are approximately 2.7:1. Twitter/X header is 3:1. YouTube thumbnails are 16:9. LinkedIn posts are 1.91:1.
16:9 (1920×1080) is the standard widescreen format for televisions, phones, and consumer monitors. 16:10 (1920×1200) is slightly taller and is common on professional laptop screens and older Mac displays — it provides more vertical space for productivity work. 16:10 has a ratio of approximately 1.6:1.