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How do I calculate aspect ratio from width and height?

Enter the width and height in pixels and this calculator instantly shows the simplified ratio (e.g., 16:9), decimal value, CSS aspect-ratio property, visual preview, and a table of equivalent sizes at common resolutions. Use the Resize tab to scale dimensions while preserving proportions, or browse Device Presets for phones, tablets, monitors, and social media formats. Everything runs in your browser — no signup required.

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Aspect Ratio Calculator

Calculate, convert, and resize aspect ratios for images, video, and responsive design.

Enter Dimensions

Result

16:9
Aspect Ratio
1.7778
Decimal
1920 × 1080
aspect-ratio: 16 / 9;

Common Aspect Ratios

Equivalent Sizes at 16:9

WidthHeightPixelsLabel
3201800.1 MP
4802700.1 MP
6403600.2 MP
7684320.3 MP
9605400.5 MP
10245760.6 MP
12807200.9 MP720p / HD
14408101.2 MP
16009001.4 MP
192010802.1 MP1080p / Full HD
256014403.7 MP1440p / 2K
384021608.3 MP2160p / 4K UHD

Frequently Asked Questions

How do I calculate the aspect ratio of an image?
Divide the width by the height to get the decimal ratio (e.g., 1920 ÷ 1080 = 1.7778). To express it as a simplified ratio, find the greatest common divisor (GCD) of both dimensions and divide — 1920:1080 simplifies to 16:9. This calculator does it automatically: enter any width and height to see the simplified ratio, decimal value, equivalent sizes, and the CSS aspect-ratio property.
What is the most common aspect ratio for video?
16:9 is the standard for HD video (720p, 1080p, 4K). Other common video ratios include 4:3 (classic TV/presentations), 21:9 (ultrawide/cinema), 9:16 (vertical video for TikTok/Reels/Shorts), and 1:1 (square, popular on Instagram). The Resize tab lets you scale any of these to a specific pixel width while preserving the ratio.
How do I resize an image without stretching it?
To maintain proportions, you need to keep the same aspect ratio. Enter your original width and height in the Resize tab, then set either the target width or height — the calculator computes the other dimension automatically. This ensures the image scales uniformly with no distortion. In CSS, the 'aspect-ratio' property and 'object-fit: contain' also help maintain ratios responsively.
What does the CSS aspect-ratio property do?
The CSS aspect-ratio property (e.g., aspect-ratio: 16 / 9) tells the browser to maintain a specific width-to-height proportion for an element. It replaced the old padding-top hack for responsive containers. Supported in all modern browsers since 2021. Combined with width: 100% and object-fit: cover, it is the cleanest way to create responsive images and video embeds that never distort.

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