How is the ratio simplified?

The tool divides both width and height by their Greatest Common Divisor (GCD). For example, 1920 and 1080 share GCD=120, so 1920÷120=16 and 1080÷120=9, giving 16:9.

In Scale mode, do I have to fill in both new width and new height?

No — fill in only one. If you enter a new width, the height is calculated automatically to maintain the original ratio. If you enter a new height, the width is calculated. If you fill both, the result shows those exact dimensions (no auto-calculation).

What is the 'Height %' shown in the result?

Height % is the height expressed as a percentage of the width. For 16:9 it is (9/16)×100 = 56.25%. This is useful in CSS when creating responsive containers with a fixed aspect ratio using the padding-top trick.

Can I use decimal dimensions?

Yes for the ratio calculation — for example 1.78 × 1 will correctly identify a ~16:9 ratio. For the scale mode, results are rounded to whole pixels since image dimensions are always integers.

Aspect Ratio Calculator

Calculate aspect ratios and resize dimensions while maintaining the correct ratio.

Design

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Common presets

Width (W)

Height (H)

How to Use

1
Choose a tab: 'Calculate Ratio' to find the ratio, or 'Scale Dimensions' to resize while keeping the ratio.
2
Or click a preset button (16:9, 4:3, 1:1, etc.) to prefill the width and height.
3
In Scale mode, enter the original dimensions then fill in either the new width OR new height — the other value is calculated automatically.
4
Click Copy on any result to copy it to your clipboard.

Use Cases

Video production and editing

Verify that your video canvas (e.g. 1280×720) matches a standard ratio like 16:9, or calculate an export size that maintains the correct ratio for a different platform.

Web and UI design

Scale an image or container from desktop (1440px wide) to mobile (375px) and get the correct height without distortion.

Social media content creation

Different platforms require different ratios — Instagram feed (4:5), Stories (9:16), YouTube thumbnail (16:9). Quickly verify or scale your artboard to the right dimensions.

Photography and printing

Confirm that a photo crop will fit a print size (e.g. 4×6 or A4) without cropping, or calculate the pixel dimensions needed for a specific print resolution.

Frequently Asked Questions

Aspect Ratio Calculator helps you find the simplified ratio of any width×height combination (e.g. 1920×1080 → 16:9) and scale dimensions to a new size while preserving the ratio perfectly. Includes common presets for video, social media, and photography.

16:9 means for every 16 units of width there are 9 units of height. It is the standard widescreen ratio used for most HD and 4K video formats, TV screens, and YouTube. 1920×1080 (Full HD) and 3840×2160 (4K) are both 16:9.

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