What is an aspect ratio?

An aspect ratio describes the proportional relationship between the width and height of an image, video or screen, written as width:height. For example, 16:9 means that for every 16 units of width there are 9 units of height, regardless of the actual pixel size.

How do I find the aspect ratio from pixels?

Divide both width and height by their greatest common divisor (GCD). For 1920 × 1080 the GCD is 120, so the ratio is 16:9. For 1080 × 1080 the GCD is 1080, so the ratio is 1:1.

Why does my resolution not give a clean ratio?

Some resolutions are close to a standard ratio but not exact. For example, 1366 × 768 simplifies to 683:384, which is very close to 16:9 but not identical. The calculator shows both the exact simplified ratio and the nearest standard ratio.

Why should video dimensions be even numbers?

Many video codecs and encoders store colour information at half resolution (4:2:0 subsampling), so they typically require both the width and height to be even numbers. Turn on the even-number option to round the result accordingly.

Which aspect ratio should I use for social media and video?

Commonly used ratios are 1:1 for square posts, 4:5 for portrait feed posts, 9:16 for full-screen vertical video such as Stories, Reels and Shorts, and 16:9 for widescreen video such as YouTube. Platforms update their recommendations from time to time, so confirm the current specification on the platform before exporting.

What is the aspect ratio of 1920 × 1080?

1920 × 1080 has an aspect ratio of 16:9. The greatest common divisor of 1920 and 1080 is 120, and 1920 ÷ 120 = 16 while 1080 ÷ 120 = 9.

What is the difference between aspect ratio and resolution?

Aspect ratio is the shape of an image or screen (width:height), while resolution is the actual number of pixels (width × height). Many different resolutions share one aspect ratio: 1280 × 720, 1920 × 1080 and 3840 × 2160 are all 16:9.

Aspect Ratio Calculator

Aspect Ratio Calculator — Ratio ⇄ Pixels

Q: How do I convert a ratio to pixels?

Pick one side in pixels and scale the other. If you know the width, height = width × (ratio height ÷ ratio width). If you know the height, width = height × (ratio width ÷ ratio height). For example, 16:9 at a width of 1920 px gives a height of 1920 × 9 ÷ 16 = 1080 px.

Turn a ratio into pixel dimensions (1:1 → 1000 × 1000, 1:2 → 1000 × 2000) or turn a width × height into its simplified ratio (1080 × 1080 → 1:1). Results update instantly as you type.

Input Details

Choose a mode, then enter your values

🔁 Conversion Mode

📐 Aspect Ratio

Popular ratios

📏 Known Side

Width (px)

Round to even numbers (recommended for video encoding)

Ratio Details

Simplified ratio

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Decimal (W ÷ H)

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CSS aspect-ratio

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Padding-top hack

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Width

Height

Pixel Details

Width

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Height

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Total pixels

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Megapixels

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Visual Preview

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Quick Copy

Same Ratio at Common Widths

✅ exact whole-pixel match · ≈ rounded to the nearest pixel

Width (px)	Height (px)	Megapixels	Match

Popular Aspect Ratios & Where They're Used

Not sure which ratio to pick? These are the ones you will run into most often, with a typical pixel size for each.

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1:1 — Square

Equal width and height. Common for profile pictures, thumbnails and square social posts. Example sizes: 1000 × 1000 and 1080 × 1080.

Square

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9:16 — Vertical Video

Full-screen phone video, used for Stories, Reels and Shorts style formats. Typical size: 1080 × 1920.

Vertical

🖼️

4:5 — Portrait

Slightly taller than square, so it takes more screen space in a feed. Typical size: 1080 × 1350.

Portrait

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16:9 — Widescreen

The standard for HD and 4K video, TVs, monitors and YouTube-style players. Typical sizes: 1920 × 1080 and 3840 × 2160.

Widescreen

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3:2 — Photography

The native shape of 35mm film and many DSLR and mirrorless camera sensors, and a common print proportion. Example size: 3000 × 2000.

Photography

🖥️

4:3 & 21:9 — Classic & Ultrawide

4:3 is the older, squarer screen shape, still common on tablets and presentations (1024 × 768). 21:9 is the cinematic ultrawide shape (2560 × 1080).

Screens

Common Resolutions & Their Aspect Ratios

Wondering what the aspect ratio of 1920 × 1080 or 1366 × 768 is? This table lists the exact simplified ratio for popular screen, video and social media sizes. Use the calculator above for any other size.

Common resolutions and their aspect ratios
Resolution (px)	Aspect ratio	Typical use
1280 × 720	16:9	HD (720p) video
1920 × 1080	16:9	Full HD (1080p) monitors, TVs and video
2560 × 1440	16:9	QHD (1440p) monitors
3840 × 2160	16:9	4K UHD video and displays
1366 × 768	683:384 (≈ 16:9)	Common on older laptops
1024 × 768	4:3	Classic displays and presentations
1920 × 1200	8:5 (16:10)	WUXGA monitors and laptops
2560 × 1080	64:27 (≈ 21:9)	Ultrawide monitors
1080 × 1080	1:1	Square social posts
1080 × 1350	4:5	Portrait feed posts
1080 × 1920	9:16	Full-screen vertical video
3000 × 2000	3:2	Photography and prints

How to Use This Aspect Ratio Calculator

Pick Ratio → Pixels when you know the shape you want (say 4:5) and one side in pixels, and need the other side. Pick Pixels → Ratio when you already have a width and height and want to know the ratio. Either way, the page shows the result, a visual preview, and the same ratio at common widths so you can pick the size that suits your project.

The Formulas Behind the Calculator

Ratio to pixels: if you know the width, height = width × (ratio height ÷ ratio width); if you know the height, width = height × (ratio width ÷ ratio height). Pixels to ratio: divide width and height by their greatest common divisor (GCD). For example, 1920 × 1080 has a GCD of 120, which gives 16:9, and 1080 × 1080 gives 1:1.

Decimal Ratios and Rounding

You can enter decimal ratios such as 1.91:1. Pixels are whole numbers, so some results (16:9 at a width of 1000 gives a height of 562.5) need rounding — the calculator tells you the exact value and what it rounded to. Switch on the even-number option to round both sides to even values for video.

Aspect Ratio Calculator — Ratio ⇄ Pixels

Popular Aspect Ratios & Where They're Used

Common Resolutions & Their Aspect Ratios

How to Use This Aspect Ratio Calculator

The Formulas Behind the Calculator

Decimal Ratios and Rounding

More on Resizing Without Distortion

Aspect Ratio FAQs