An aspect ratio calculator helps you find the proportional relationship between width and height. Enter any two values — width and height, width and ratio, or height and ratio — and the tool instantly computes the missing dimension. Essential for designers, videographers, and developers who need pixel-perfect resizing without distortion.
Dimensions
Result
Common Resolutions
| Name | Width | Height | Ratio |
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How to Use the Aspect Ratio Calculator
Whether you are resizing images for a website, setting up a video export, or choosing a display resolution, maintaining the correct aspect ratio prevents stretching and cropping. This calculator does the maths for you — enter any two of three values (width, height, ratio) and get the third instantly.
Step 1: Enter Known Dimensions
Type your known width and height into the input fields. The calculator immediately computes the simplified aspect ratio using the greatest common divisor. For example, entering 1920 and 1080 returns 16:9.
Step 2: Or Use a Preset Ratio
Click one of the common preset buttons — 16:9, 4:3, 1:1, 21:9, 9:16, 3:2, or 2:3 — to lock in a ratio. Then enter either width or height and the calculator finds the missing dimension. This is useful when you know you need a widescreen or portrait layout but are unsure of the exact pixel count.
Step 3: Read the Results
The result panel shows width, height, the simplified ratio, and a decimal value. The visual preview rectangle scales proportionally so you can see the shape at a glance. Click Copy Result to copy the dimensions to your clipboard for use in design software, CSS, or video editors.
Common Use Cases
Video production: Most platforms expect 16:9 (landscape) or 9:16 (vertical). Photography: DSLR sensors typically shoot at 3:2, while compact cameras and older phones use 4:3. Web design: Hero images, thumbnails, and Open Graph cards each have ideal ratios — this aspect ratio calculator helps you resize without trial and error.
Reference Table
The resolutions table below the calculator lists popular standards — from 720p and 1080p through 4K and 8K, plus common social media and mobile screen sizes. Click any row to load its values into the calculator for quick adjustments.
Frequently Asked Questions
Is this aspect ratio calculator free?
Yes, this tool is completely free with no account, login, or signup required. All calculations run instantly in your browser and no data is sent to any server.
Is my data private when using this tool?
Absolutely. Everything runs locally in your browser. No dimensions or calculations are transmitted, stored, or logged anywhere. You can use it offline once the page has loaded.
What is aspect ratio and why does it matter?
Aspect ratio is the proportional relationship between width and height, expressed as W:H (e.g., 16:9). It matters because resizing an image or video without maintaining the correct ratio causes stretching or cropping, which distorts the content.
How do I calculate aspect ratio from width and height?
Enter both width and height into the calculator. The tool finds the greatest common divisor (GCD) of the two values and divides both by it to produce the simplified ratio. For example, 1920 and 1080 share a GCD of 120, giving 16:9.
What aspect ratio is best for YouTube videos?
YouTube recommends 16:9 for standard videos, with 1920x1080 (1080p) or 3840x2160 (4K) being the most common resolutions. YouTube Shorts use a 9:16 vertical ratio at 1080x1920 pixels.
What is the difference between 16:9 and 4:3?
16:9 is a widescreen format used by modern monitors, TVs, and video platforms. 4:3 is the older, more square format used by classic TVs and some presentations. 16:9 is wider relative to its height, giving more horizontal viewing space.
Can I use this calculator for print dimensions?
Yes. Enter any width and height in any unit — pixels, inches, centimeters, or millimeters. The aspect ratio is a pure proportion, so the unit does not affect the result. Common print ratios include 3:2 (standard photo) and 5:7 (portrait print).