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Free Aspect Ratio Calculator

Find the aspect ratio of any width and height and calculate a matching size for a new width.

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How to use this tool

Resizing a video, a thumbnail or a banner without stretching it starts with its aspect ratio. Enter a width and height in pixels to see the simplified ratio, the nearest common ratio when the numbers don’t divide cleanly, and the ratio as a decimal. Add a new width and the calculator gives the matching height.

  1. 01

    Enter width and height

    Type the original size in pixels, or any unit, as long as both use the same one.

  2. 02

    Read the ratio

    See the ratio in its simplest form, such as 16:9, or the closest common ratio when it doesn’t simplify neatly, plus the decimal value.

  3. 03

    Resize without distortion

    Optionally add a new width to get the height that keeps the same shape. Copy the numbers into your editor or export settings.

How aspect ratio is calculated

Aspect ratio is width divided by height. To simplify it, divide both by their greatest common divisor: 1920 and 1080 share 120, so 1920 × 1080 is 16:9. Some sizes don’t reduce to small numbers; 1366 × 768 is exactly 683:384, so the calculator also shows the nearest common ratio, ≈ 16:9.

Common social media ratios

• 16:9: YouTube videos, thumbnails (1280 × 720) and landscape video. • 9:16: TikTok, Reels, Shorts and Stories (1080 × 1920). • 1:1: square posts (1080 × 1080). • 4:5: Instagram portrait posts (1080 × 1350). • 1.91:1: link previews and landscape Instagram posts (1200 × 628). • 3:1: X / Twitter headers (1500 × 500).

Resizing without stretching

New height = new width ÷ (original width ÷ original height). Round to whole pixels; many video encoders also prefer even numbers. If the target platform needs a different ratio, crop or add padding instead of stretching, or use the social media image and video resizers, which handle crop and fit for you.

Ratio vs resolution

Resolution is the number of pixels, such as 1920 × 1080; aspect ratio is the shape. 3840 × 2160 (4K) and 1280 × 720 (HD) have the same 16:9 shape at very different resolutions. Upload at the highest resolution the platform accepts in the ratio it expects.

Frequently asked questions

How do I calculate aspect ratio?

Divide the width and height by their greatest common divisor. For 1920 × 1080 both divide by 120, giving 16:9.

What is 16:9 in pixels?

Common 16:9 sizes are 1280 × 720 (HD), 1920 × 1080 (Full HD), 2560 × 1440 (QHD) and 3840 × 2160 (4K).

How do I keep the aspect ratio when resizing?

Enter the original width and height and the new width. The calculator returns the height that keeps the same shape.

What aspect ratio is 1080 × 1350?

It’s 4:5, the tallest portrait ratio Instagram shows in the feed.

What aspect ratio do TikTok and Reels use?

9:16 vertical video, usually 1080 × 1920 pixels.

Why does it show “≈” before some ratios?

Some sizes don’t simplify to small whole numbers. When the exact ratio has large numbers, the calculator shows the nearest common ratio within about 1%.

What does the decimal ratio mean?

It’s width divided by height. 16:9 is 1.778:1 and 4:3 is 1.333:1, which makes ratios easy to compare.

Can I use units other than pixels?

Yes. Inches, centimeters or any unit work, as long as width and height use the same one.

Are my numbers stored?

No. The calculation runs in your browser and nothing is sent to SocQ or saved.

Is the aspect ratio calculator free?

Yes. It’s free with no signup and no limit.

For developers

Get video details from public YouTube data

SocQ APIs return public YouTube videos, channels, transcripts and comments, so you can analyze formats, lengths and performance across many channels.

Explore the API

youtube/videos

posts0.5 credits / result

youtube/channels

profiles0.26 credits / result

youtube/transcripts

posts0.5 credits / result

youtube/comments

comments0.3 credits / result

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