Aspect Ratio Calculator: Screen Resolutions, Video Formats, and Print Explained
Reviewed by Jerry Croteau, Founder & Editor
Table of Contents
Aspect ratio is the proportional relationship between width and height. It determines whether a video looks cinematic or boxy, whether a photo prints cleanly or gets cropped, and whether a design element fits a specific platform's frame. Understanding it saves you from distorted images, awkward crops, and videos with black bars where you do not want them.
Our converts between any dimensions and ratios. This guide covers the most common formats and the math behind them.
How aspect ratio is expressed
Aspect ratio is written as width:height, reduced to its simplest form. A 1920x1080 resolution has a ratio of 1920:1080, which reduces to 16:9. A 2048x1536 iPad display is 4:3. A square image is 1:1.
To find the ratio from any two dimensions:
- Find the greatest common divisor (GCD) of width and height
- Divide both by the GCD
Example: 1280x720. GCD of 1280 and 720 is 80. 1280/80 = 16, 720/80 = 9. Ratio: 16:9.
Common aspect ratios and their uses
| Ratio | Decimal | Primary use | Example resolutions |
|---|---|---|---|
| 16:9 | 1.78 | HD/4K video, most monitors, YouTube | 1920x1080, 3840x2160 |
| 4:3 | 1.33 | Old TV, iPad, photography | 1024x768, 2048x1536 |
| 1:1 | 1.00 | Instagram square, profile photos | 1080x1080 |
| 9:16 | 0.56 | Vertical video, Stories, Reels, TikTok | 1080x1920 |
| 2.39:1 | 2.39 | Cinematic widescreen film | 2048x858 (DCP) |
| 1.85:1 | 1.85 | US theatrical film standard | 1998x1080 (2K DCP) |
| 21:9 | 2.33 | Ultrawide monitors, some mobile | 2560x1080, 3440x1440 |
| 3:2 | 1.50 | 35mm film, DSLR cameras, prints | 4288x2848 (Canon 7D) |
Calculating missing dimensions
Given one dimension and the ratio, you can find the other:
Height = Width / (ratio width / ratio height)
Width = Height x (ratio width / ratio height)
Example: 16:9 video at 1200px width
Height = 1200 / (16/9) = 1200 / 1.778 = 675px
Example: 4:3 image 800px tall
Width = 800 x (4/3) = 800 x 1.333 = 1067px
Print aspect ratios and photo sizes
Print dimensions are usually in inches, and standard print sizes have specific ratios that do not always match digital camera sensors:
| Print size | Ratio | Fits 3:2 sensor natively? |
|---|---|---|
| 4x6" | 3:2 | Yes — perfect fit |
| 5x7" | 7:5 = 1.4:1 | No — slight crop |
| 8x10" | 5:4 = 1.25:1 | No — significant crop |
| 8x12" | 3:2 | Yes — perfect fit |
| 11x14" | 1.27:1 | No — crop required |
| 16x20" | 5:4 | No — significant crop |
When printing a DSLR photo at 8x10, you will lose about 13% of the image width or height depending on how the lab crops it. Compose shots with this in mind, or use a custom crop in your editing software before ordering prints.
Why letterboxing and pillarboxing happen
Letterboxing (black bars on top and bottom): a wider source (like 2.39:1 film) displayed on a narrower container (like 16:9). The bars fill the unused height.
Pillarboxing (black bars on left and right): a narrower source (like 4:3 old TV) displayed in a wider container (like 16:9). Also called "windowboxing."
To eliminate bars, you must either crop the source (losing content) or stretch it (causing distortion). There is no lossless way to fill a container with content of a different ratio — something must give.
Social media aspect ratios (2026 standards)
| Platform / format | Recommended ratio | Pixel dimensions |
|---|---|---|
| YouTube video | 16:9 | 1920x1080 minimum |
| Instagram square post | 1:1 | 1080x1080 |
| Instagram landscape post | 1.91:1 | 1080x566 |
| Instagram portrait post | 4:5 | 1080x1350 |
| Instagram/TikTok Stories/Reels | 9:16 | 1080x1920 |
| X (Twitter) image | 16:9 | 1600x900 |
| LinkedIn post image | 1.91:1 | 1200x627 |
Use the to quickly find dimensions for any ratio — useful when sizing images for design mockups, social media, or print without running the math manually.
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