What is aspect ratio?

Aspect ratio is the proportional relationship between the width and height of an image, video, or screen, expressed as two numbers separated by a colon (e.g., 16:9). Use this aspect ratio calculator to find, lock, and convert ratios without doing the math manually.

What are the most common aspect ratios?

16:9 is the standard for HD video and most modern monitors, 4:3 was the traditional TV and older monitor ratio, 1:1 is popular for Instagram square posts, and 21:9 is used for ultra-wide cinema displays. This aspect ratio calculator includes presets for all of these and more.

How do I calculate the aspect ratio of an image?

Enter the width and height of your image into the aspect ratio calculator and it will instantly reduce the values to their simplest ratio form using the greatest common divisor. For example, a 1920×1080 image reduces to a 16:9 aspect ratio.

How does aspect ratio apply to video production?

For video, aspect ratio determines how the frame fills the screen: 16:9 is the universal standard for YouTube, streaming, and broadcast, while vertical 9:16 is used for Reels and TikTok. An aspect ratio calculator helps you set the correct canvas dimensions before exporting to avoid black bars or cropping.

What aspect ratio should I use for social media?

Instagram feed posts work best at 1:1 (square) or 4:5 (portrait), Stories and Reels use 9:16, Twitter/X recommends 16:9, and LinkedIn favors 1.91:1 for link previews. This aspect ratio calculator can compute the exact pixel dimensions for any of these ratios given one known side.

Aspect Ratio Calculator — Free Online Ratio Tool

Aspect Ratio Calculator

Calculate and convert aspect ratios for images, video, and screens.

Processed locally in your browser

Calculate and convert aspect ratios for images, video, and screen resolutions with this free online calculator.

Width (px)

Height (px)

Aspect Ratio

16:9

Decimal

1.7778

Megapixels

2.07 MP

Preview

1920×1080

Common Ratios

Social Media Sizes

Resolution Presets

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How to Use

Calculate and convert aspect ratios for images, video, and screen resolutions with this free online calculator.

Enter width and height. Type the pixel dimensions of your image or video into the width and height fields. The calculator instantly displays the simplified aspect ratio (e.g., 1920×1080 → 16:9).
Lock the ratio. Click the lock icon to constrain proportions. Now when you change the width, the height adjusts automatically to maintain the same aspect ratio — and vice versa.
Use a preset. Select a common ratio like 16:9 (widescreen), 4:3 (standard), 1:1 (square), or 9:16 (vertical mobile) from the presets. Enter one dimension and the calculator fills in the other.
Check the megapixel count. The tool shows the total megapixels for your current dimensions — useful when working with camera sensor specifications or print resolution requirements.
Copy the values. Use the copy button to grab the ratio, dimensions, or megapixel count for your design specs, export settings, or documentation.

This calculator is ideal for designers, video editors, and developers who need to resize media while preserving proportions. All calculations run in your browser — no data leaves your device.

Features

✓Calculate ratio from dimensions
✓Lock ratio and resize proportionally
✓Popular preset ratios
✓Visual ratio preview
✓Megapixel calculation
✓Copy results

Frequently Asked Questions

What is aspect ratio?: Aspect ratio is the proportional relationship between the width and height of an image, video, or screen, expressed as two numbers separated by a colon (e.g., 16:9). Use this aspect ratio calculator to find, lock, and convert ratios without doing the math manually.
What are the most common aspect ratios?: 16:9 is the standard for HD video and most modern monitors, 4:3 was the traditional TV and older monitor ratio, 1:1 is popular for Instagram square posts, and 21:9 is used for ultra-wide cinema displays. This aspect ratio calculator includes presets for all of these and more.
How do I calculate the aspect ratio of an image?: Enter the width and height of your image into the aspect ratio calculator and it will instantly reduce the values to their simplest ratio form using the greatest common divisor. For example, a 1920×1080 image reduces to a 16:9 aspect ratio.
How does aspect ratio apply to video production?: For video, aspect ratio determines how the frame fills the screen: 16:9 is the universal standard for YouTube, streaming, and broadcast, while vertical 9:16 is used for Reels and TikTok. An aspect ratio calculator helps you set the correct canvas dimensions before exporting to avoid black bars or cropping.
What aspect ratio should I use for social media?: Instagram feed posts work best at 1:1 (square) or 4:5 (portrait), Stories and Reels use 9:16, Twitter/X recommends 16:9, and LinkedIn favors 1.91:1 for link previews. This aspect ratio calculator can compute the exact pixel dimensions for any of these ratios given one known side.