Aspect Ratio Calculator
This aspect ratio calculator computes and converts display dimensions while maintaining the correct proportions. Enter width and height to find the aspect ratio, or enter a ratio and one dimension to calculate the other for video, photos, and screen resolutions.
Aspect Ratio Calculator
Calculate and convert between aspect ratios and pixel dimensions. Lock the ratio to maintain proportions while adjusting values.
Common Presets
Dimensions
Ratio
Pixels
Frequently Asked Questions
What is aspect ratio?
Aspect ratio is the proportional relationship between the width and height of an image, video, or screen. It is expressed as two numbers separated by a colon, such as 16:9 or 4:3. The first number represents the width and the second represents the height. Aspect ratio describes the shape of the display, not its size. A 16:9 ratio means that for every 16 units of width, there are 9 units of height.
What is the most common aspect ratio?
The most common aspect ratio is 16:9 (also written as 1.78:1), which is the standard for HDTV, most computer monitors, and online video platforms like YouTube. Other common ratios include 4:3 (traditional TV and older monitors), 21:9 (ultrawide monitors and cinematic films), 1:1 (square, used on social media), and 9:16 (vertical video for mobile platforms like TikTok and Instagram Stories).
How do you calculate aspect ratio from dimensions?
To calculate the aspect ratio from pixel dimensions, divide both the width and height by their greatest common divisor (GCD). For example, for 1920x1080: the GCD of 1920 and 1080 is 120, so divide both by 120 to get 16:9. You can also divide width by height to get a decimal ratio: 1920/1080 = 1.778, which corresponds to 16:9. This method works for any resolution.
What aspect ratio is 1920x1080?
1920x1080 pixels has an aspect ratio of 16:9. This is the standard Full HD (1080p) resolution. Other common 16:9 resolutions include 1280x720 (720p HD), 2560x1440 (1440p QHD), and 3840x2160 (4K UHD). The 16:9 ratio is the most widely used aspect ratio for monitors, TVs, and video content because it provides a good balance between horizontal and vertical viewing area.
How do you resize an image while keeping aspect ratio?
To resize an image while maintaining its aspect ratio, change one dimension and calculate the other proportionally. Use the formula: new height = new width × (original height / original width). For example, to resize a 1920x1080 image to 1280 pixels wide: 1280 × (1080/1920) = 720 pixels tall. Most image editors do this automatically when you lock the aspect ratio or hold Shift while resizing.
What is the difference between 16:9 and 4:3?
16:9 is wider and shorter (widescreen), while 4:3 is more square-shaped (standard). At the same diagonal size, a 16:9 screen is about 13% wider but 25% shorter than a 4:3 screen. 16:9 is the modern standard for HD and 4K content, while 4:3 was the standard for analog TV and early computer monitors. When 4:3 content is displayed on a 16:9 screen, black bars (pillarboxing) appear on the sides.
What aspect ratio do smartphones use?
Most modern smartphones use aspect ratios between 19.5:9 and 20:9 in landscape orientation (or 9:19.5 to 9:20 in portrait). Common smartphone ratios include 19.5:9 (iPhone), 20:9 (Samsung Galaxy), and 19:9. Older smartphones used 16:9. Foldable phones may use ratios closer to 4:3 when unfolded. When creating content for mobile viewing, vertical 9:16 is standard for stories and short-form video.
What aspect ratio should I use for YouTube?
YouTube uses 16:9 (1920×1080) as its standard aspect ratio. Vertical videos should use 9:16 (1080×1920) for Shorts. If you upload a different ratio, YouTube will add black bars (letterboxing or pillarboxing) to fit.
What is the best aspect ratio for Instagram?
Instagram supports multiple ratios: 1:1 (1080×1080) for square posts, 4:5 (1080×1350) for portrait posts which get the most screen space in feeds, and 9:16 (1080×1920) for Stories and Reels. For maximum engagement, use 4:5 for feed posts.
What aspect ratio is 2560×1600?
2560×1600 has a 16:10 (or 8:5) aspect ratio. This is commonly used in MacBook Pro displays and some Dell/HP monitors. To find the ratio, divide both dimensions by their greatest common divisor (GCD): 2560÷160 = 16, 1600÷160 = 10.
Common Aspect Ratios Reference Table
The table below lists every major aspect ratio you will encounter in video production, photography, web design, and social media. Use it as a quick-reference when choosing dimensions for your project.
Table of Contents
- Common Aspect Ratios Reference Table
- Video Aspect Ratios (16:9, 4:3, 21:9)
- Photography Aspect Ratios (3:2, 4:5, 1:1)
- Cinema Aspect Ratios (2.35:1, 2.39:1, 1.85:1)
- Social Media Aspect Ratios
- How to Calculate Aspect Ratio
- How to Resize Images While Keeping Aspect Ratio
- Practical Applications
- Related Calculators
Aspect Ratio Comparison Chart
This comprehensive table covers all standard aspect ratios used in video, photography, cinema, and digital media. The decimal value lets you compare how wide or tall each format is relative to a square (1.0).
| Ratio | Decimal | Common Resolutions | Use Case |
|---|---|---|---|
| 9:16 | 0.5625 | 1080×1920 | TikTok, Instagram Reels, YouTube Shorts |
| 4:5 | 0.8 | 1080×1350 | Instagram portrait posts |
| 1:1 | 1.0 | 1080×1080 | Instagram posts, profile pictures |
| 4:3 | 1.33 | 1024×768, 1600×1200 | Classic TV, iPad, presentations |
| 3:2 | 1.5 | 1080×720, 6000×4000 | DSLR photos, 35mm film |
| 16:10 | 1.6 | 1920×1200, 2560×1600 | MacBook, widescreen monitors |
| 16:9 | 1.78 | 1920×1080, 3840×2160 | HDTV, YouTube, modern monitors |
| 1.85:1 | 1.85 | 1998×1080 | US theatrical standard |
| 21:9 | 2.33 | 2560×1080, 3440×1440 | Ultrawide monitors, cinema |
| 2.35:1 | 2.35 | 1920×817 | Anamorphic widescreen cinema |
| 2.39:1 | 2.39 | 4096×1716 | Modern cinema (Scope) |
Video Aspect Ratios (16:9, 4:3, 21:9)
16:9is the universal standard for HD and 4K video. Every major streaming platform, broadcast network, and video camera defaults to 16:9. Common resolutions include 1280×720 (720p), 1920×1080 (1080p Full HD), 2560×1440 (1440p QHD), and 3840×2160 (4K UHD).
4:3was the standard aspect ratio for television from the 1940s through the early 2000s. Today it is still used on iPads, some security cameras, and presentation slide formats (1024×768, 1600×1200). Old TV shows and classic films were shot in 4:3 and will show black bars (pillarboxing) on modern 16:9 screens.
21:9(ultrawide) is popular for immersive gaming monitors and cinematic video content. Ultrawide displays at 2560×1080 or 3440×1440 provide a wider field of view that closely matches theatrical cinema proportions.
Photography Aspect Ratios (3:2, 4:5, 1:1)
3:2is the native aspect ratio of 35mm film and most DSLR/mirrorless cameras. Standard print sizes like 4×6 inches and 6×9 inches maintain this ratio. Professional photographers typically shoot in 3:2 and crop to other ratios during post-processing.
4:5(portrait orientation) is the tallest ratio Instagram allows for feed posts at 1080×1350 pixels. It occupies more vertical screen space in the feed than a square or landscape image, which can increase engagement. The 8×10 inch print size also uses a 4:5 ratio.
1:1(square) became iconic through Instagram's original square-only format. At 1080×1080 pixels it remains a popular choice for profile pictures, album art covers, and e-commerce product images where a consistent grid layout is desired.
Cinema Aspect Ratios (2.35:1, 2.39:1, 1.85:1)
2.35:1 (anamorphic widescreen, also called CinemaScope) uses special anamorphic lenses to squeeze a wide image onto standard 35mm film and then unsqueeze it during projection. This ratio is favored for epic landscapes and action sequences.
2.39:1 (Scope) is the modern successor to 2.35:1 and the most common widescreen ratio in contemporary Hollywood films. The slight difference from 2.35:1 comes from adjustments in the SMPTE standard to account for the area between film frames.
1.85:1(US theatrical standard, also called "flat") is used for most non-scope theatrical releases in the United States. It sits between the 16:9 TV ratio and the wider 2.39:1 scope ratio, providing a modest widescreen look without extreme horizontal stretching.
How to Calculate Aspect Ratio
Aspect Ratio Formula
The aspect ratio is the proportional relationship between width and height. You can express it as a simple division or as a simplified integer ratio:
To get the simplified integer ratio (e.g., 16:9), divide both the width and height by their greatest common divisor (GCD):
Step-by-Step Calculation Example
Given:A display with dimensions 2560×1440 pixels.
- Compute the decimal ratio: 2560 ÷ 1440 = 1.778
- Find the GCD of 2560 and 1440. The GCD is 320.
- Divide width by GCD: 2560 ÷ 320 = 8
- Divide height by GCD: 1440 ÷ 320 = 4.5
- Multiply both by 2 to get integers: 16 : 9
Result: 2560×1440 has a 16:9 aspect ratio, the same shape as 1920×1080 Full HD and 3840×2160 4K UHD.
Finding Aspect Ratio from Pixel Dimensions
Any resolution can be reduced to its aspect ratio by following these steps:
- Enter the width and height in pixels (e.g., 1920 and 1080).
- Calculate the GCD of the two numbers. For 1920 and 1080, the GCD is 120.
- Divide width by GCD: 1920 ÷ 120 = 16
- Divide height by GCD: 1080 ÷ 120 = 9
- The aspect ratio is 16:9.
This method works for any pair of dimensions. For example, 2560×1600 has a GCD of 160, giving 16:10 (or 8:5). A 4000×3000 photo has a GCD of 1000, giving 4:3.
Quick shortcut:Divide width by height on a calculator. If the result is approximately 1.78, the ratio is 16:9. If it's approximately 1.33, it's 4:3. If it's 1.5, it's 3:2. Memorizing these decimal values lets you identify common ratios at a glance.
How to Resize Images While Keeping Aspect Ratio
When you resize an image, video, or design element, you need to keep the original aspect ratio to prevent stretching or squashing. The formula is straightforward:
Example:Resize a 1920×1080 image to 1280 pixels wide while preserving the 16:9 ratio:
- new_height = 1080 × (1280 ÷ 1920)
- new_height = 1080 × 0.6667
- new_height = 720
The resized image is 1280×720, which is still 16:9 (standard 720p HD).
Quality tips:
- Always resize down from a larger original when possible. Upscaling introduces blur and artifacts.
- Most image editors (Photoshop, GIMP, Figma) have a "lock aspect ratio" toggle — keep it enabled to avoid accidental distortion.
- For web images, export at 2× the display size for sharp rendering on Retina and high-DPI screens.
Practical Applications
Understanding aspect ratios is essential across a wide range of creative and technical disciplines:
- Video production and editing— Match your timeline settings to the delivery platform (16:9 for YouTube, 9:16 for TikTok).
- Web design — Use the CSS
aspect-ratioproperty to create responsive containers that maintain proportions at any viewport width. - Photography— Crop images to standard print ratios (3:2 for 4×6, 5:4 for 8×10) before sending to the printer.
- Social media marketing— Prepare platform-specific assets in bulk (1:1 feed, 4:5 portrait, 9:16 stories) to maximize engagement.
- Print and graphic design— Calculate scaled dimensions for posters, banners, and signage while keeping logos and photos proportionally correct.
- Monitor and TV shopping— Compare screen shapes: a 34-inch ultrawide (21:9) and a 32-inch standard (16:9) have very different viewing experiences despite similar diagonal measurements.
For a deeper dive into aspect ratios across video, photo, and social media, read our Complete Guide to Aspect Ratios.
Social Media Aspect Ratios
Each social media platform has preferred dimensions for images and video. Using the correct aspect ratio prevents cropping, black bars, and low-quality scaling. Below is a platform-by-platform breakdown.
Tip: When creating content for multiple platforms simultaneously, shoot in 9:16 vertical and crop to 1:1 or 4:5 for feed posts. This gives you the most flexibility from a single recording session.