Aspect Ratio Calculator
Calculate aspect ratios, determine missing dimensions, and resize proportions accurately for video, photography, web design, and social media.
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16:9 (Landscape)The preview box updates dynamically with your exact calculated aspect ratio.
Common Ratios
What Is an Aspect Ratio?
An aspect ratio is the proportional relationship between a geometric shape or digital frame’s width and height. It is conventionally expressed as two whole numbers separated by a colon, written in the format Width:Height (or W:H).
Importantly, aspect ratio describes the shape of the frame, not its physical measurement or digital pixel resolution. For example, a square image measuring 500×500 pixels, an Instagram icon measuring 1080×1080 pixels, and a printed ceramic tile measuring 8×8 inches all share the identical 1:1 aspect ratio. Similarly, a 1280×720 HD video and a 3840×2160 4K Ultra HD video both share the ubiquitous 16:9 widescreen ratio.
Two reduced whole numbers representing horizontal width relative to vertical height.
A decimal value (e.g. 1920 ÷ 1080 = 1.7778) used in CSS calculations and video engine scaling.
Dividing both dimensions by their Greatest Common Divisor yields the irreducible fractional ratio.
How to Calculate Aspect Ratio Manually
Whether you are calculating the ratio of a custom graphic, video resolution, or physical canvas, you can calculate the aspect ratio in three simple steps:
Determine Width & Height
Record your pixel or metric dimensions. For instance, consider a digital camera frame measuring 1920 pixels wide by 1080 pixels high.
Find Greatest Common Divisor
Calculate the largest integer that divides both numbers evenly without a remainder. For 1920 and 1080, the GCD is 120.
Divide Both Numbers
Divide width by GCD: 1920 ÷ 120 = 16.
Divide height by GCD: 1080 ÷ 120 = 9.
The final ratio is 16:9.
Common Aspect Ratios Guide
Explore the most widely used aspect ratios across digital media, social networks, photography, and video broadcasting:
| Ratio | Decimal | Industry Category | Typical Usage & Devices |
|---|---|---|---|
| 16:9 | 1.78:1 | Video / Displays | The universal widescreen standard for modern TV, YouTube, PC monitors, and digital cameras. |
| 9:16 | 0.56:1 | Vertical Video | Standard mobile vertical video format for TikTok, Instagram Reels, YouTube Shorts, and Snapchat. |
| 4:3 | 1.33:1 | Classic Displays / Tablet | Legacy television standard, iPad displays, and Micro Four Thirds digital camera sensors. |
| 1:1 | 1.00:1 | Square | Traditional medium format film, Instagram square posts, avatar photos, and product thumbnail tiles. |
| 3:2 | 1.50:1 | 35mm Photography | Classic 35mm film standard, full-frame DSLRs, mirrorless cameras, and Microsoft Surface screens. |
| 21:9 | 2.33:1 | Ultrawide Cinema | Ultra-wide cinematic widescreen, panoramic PC gaming monitors, and anamorphic film presentations. |
| 4:5 | 0.80:1 | Portrait Social | Optimal portrait post dimension for Instagram feed posts (e.g. 1080×1350) to maximize mobile screen real estate. |
How to Resize Dimensions Without Distortion
When scaling an asset for web design, video production, or print, stretching width or height independently leads to unpleasant stretching or squishing. To preserve proportional fidelity:
Use Mode 4 "Resize Dimensions" in the calculator above with the ratio lock enabled to instantly compute scale dimensions automatically.
Aspect Ratio Questions & Answers
Common questions about aspect ratios, screen resolutions, and image scaling formulas.
What is an aspect ratio?
An aspect ratio represents the proportional relationship between the width and height of an image, video, screen, or canvas. It is typically expressed as two numbers separated by a colon (such as 16:9 or 4:3), indicating that for every 16 units of width, there are 9 units of height.
How do I calculate an aspect ratio?
To calculate an aspect ratio, divide the width and height by their Greatest Common Divisor (GCD). For example, with 1920 × 1080, the GCD is 120. Dividing 1920 by 120 gives 16, and dividing 1080 by 120 gives 9, yielding the simplified ratio of 16:9.
What is the aspect ratio of 1920 × 1080?
1920 × 1080 has a standard 16:9 aspect ratio (or decimal equivalent of 1.7778). It is the most universal widescreen format used for Full HD monitors, televisions, YouTube videos, and streaming content.
What is the difference between 16:9 and 4:3?
16:9 is a rectangular widescreen ratio commonly used for modern displays, TV broadcasts, and video games. In contrast, 4:3 is a squarer standard ratio that was the standard for vintage televisions, computer monitors, and classic 35mm photography prior to the widescreen era.
How do I calculate missing height given width and ratio?
To find the missing height, multiply the width by the ratio height and divide by the ratio width: Height = Width × (Ratio Height ÷ Ratio Width). For example, if Width = 1280 and Ratio = 16:9, Height = 1280 × (9 ÷ 16) = 720 px.
How do I calculate missing width given height and ratio?
To find the missing width, multiply the height by the ratio width and divide by the ratio height: Width = Height × (Ratio Width ÷ Ratio Height). For example, if Height = 1080 and Ratio = 16:9, Width = 1080 × (16 ÷ 9) = 1920 px.
Can I use this calculator for image dimensions and resizing?
Yes. You can switch to the "Resize Dimensions" mode, enter your photo or banner original dimensions, and specify a target width or height. The calculator will automatically scale the remaining dimension while preserving the exact original aspect ratio.
Can I use it for video resolutions and screen sizes?
Yes. The calculator includes quick presets for all standard video resolutions (16:9 Widescreen, 9:16 Vertical Stories/Reels/TikTok, and 21:9 Ultrawide Cinema) and desktop/tablet screens (16:10 and 4:3).
Does the aspect ratio calculator work on mobile devices?
Yes. The calculator is completely responsive, optimized for smartphones, iPhones, and tablets with comfortable touch-friendly buttons, instant calculation, and one-tap clipboard copying.
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