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Pixel Aspect Ratio Calculator

Pixel aspect ratio (PAR) describes the proportional relationship between a pixel's width and height. Most digital content uses square pixels (1:1), but video standards and broadcast formats often employ rectangular pixels to maintain compatibility with legacy systems. Understanding PAR is essential for photographers, video editors, and motion designers working across multiple platforms and display formats.

Last updated: May 15, 2026

Creators Jasmine J. Mah, BSc

Reviewers Krishna Nelaturu and Mateusz Mucha

3,741 people find this calculator helpful

What Is Pixel Aspect Ratio?

Pixel aspect ratio quantifies how wide a pixel is relative to its height. In everyday digital photography, pixels are square, producing a 1:1 ratio. However, standard-definition television (SDTV) and certain video codecs use non-square pixels to optimize image storage and transmission.

For example, a 2:1 pixel aspect ratio means each pixel is twice as wide as it is tall. A 4:5 ratio indicates pixels that are narrower vertically, common in PAL video formats, while 16:9 pixels are wider horizontally, typical in widescreen HD workflows. Mismatched pixel aspect ratios can distort content—circles appear as ovals, text skews—making PAR critical knowledge for any digital media professional.

Calculating Pixel Aspect Ratio

The relationship between pixel dimensions and aspect ratio is straightforward. Divide the pixel width by the pixel height to obtain the aspect ratio. This formula works bidirectionally: if you know your target aspect ratio and one dimension, you can calculate the missing dimension.

Aspect Ratio = Width ÷ Height

Width = Aspect Ratio × Height

Height = Width ÷ Aspect Ratio

Aspect Ratio — The proportional relationship between pixel width and height (e.g., 16:9, 4:5, 1:1)
Width — The horizontal dimension of the pixel, measured in units
Height — The vertical dimension of the pixel, measured in units

Common Pixel Aspect Ratios in Practice

Square pixels (1:1): Used in modern digital photography, computer graphics, and web content. Nearly all contemporary cameras and displays default to this ratio.

Widescreen (16:9): Standard for HD and UHD video production, cinema, and streaming platforms. Equivalent to approximately 1.78:1.

4:3 aspect ratio: Legacy standard for older television broadcasts and some security camera systems. Produces a boxier frame than widescreen.

PAL video (4:5 or 12:11): Used in European and Asian broadcast systems. These rectangular pixels compensate for technical differences in how PAL video displays content.

DV NTSC (10:11): Standard for consumer digital video formats in North America, requiring pixel aspect ratio compensation during editing.

Critical Considerations When Working with Pixel Aspect Ratios

Understanding these pitfalls prevents distortion, misalignment, and playback issues.

Match your export settings to your delivery platform — Always confirm the target platform's native pixel aspect ratio before exporting. YouTube, Instagram, and professional broadcast each have specific requirements. Exporting square pixels to a PAL broadcast system will compress your image vertically, making subjects appear thinner than intended.
Account for PAR when scaling or resizing — If you resize an image without adjusting for PAR, rectangular pixels will become more rectangular (or vice versa), introducing unwanted distortion. Professional editing software applies PAR correction automatically, but always verify the setting is active.
Preview on the actual display format — Aspect ratio calculations are correct only if the viewing device interprets pixels correctly. A PAL project edited on a square-pixel monitor will look wrong on a PAL display. Always preview your work on the target system when possible.
Check footage metadata before editing — Legacy video footage often embeds PAR information in its codec metadata. Importing DV or HDV files without recognizing their non-square pixel aspect ratio creates subtle distortions that compound through colour correction and effects processing.

When and Why PAR Matters

Modern creators rarely encounter PAR issues because web-based video and photography have standardized on square pixels. However, PAR becomes critical when:

Working with archival or legacy video footage (DV, HDV, DVCAM)
Producing content for broadcast television or cinema distribution
Mixing footage from different cameras or formats in a single project
Adapting content for regional broadcast standards (NTSC, PAL, SECAM)
Authoring DVDs or video CDs, which may use PAL or MPEG-2 video with specific PAR requirements

For social media, web video, and digital photography, square pixel aspect ratio (1:1) is assumed by default, so manual PAR adjustment is unnecessary.

Frequently Asked Questions

Why do some pixels appear wider or taller than others?

Non-square pixel aspect ratios are deliberate engineering choices in broadcast and video codec design. PAL and NTSC video standards use rectangular pixels to optimize how images compress and transmit over limited bandwidth. When these videos are displayed on square-pixel monitors without PAR correction, circles distort into ovals and proportions shift. Professional video software automatically applies PAR correction during playback, restoring the intended appearance.

What does a 4:5 aspect ratio mean?

A 4:5 pixel aspect ratio indicates that each pixel is four units wide and five units tall—taller than it is wide. This creates vertically compressed pixels. When displayed on a standard square-pixel monitor, content shot with 4:5 pixels appears narrower or more vertically stretched. This ratio is common in PAL video formats used in Europe, Africa, and Asia. Understanding this ratio is essential if you're working with PAL DV footage or broadcast archival material.

How do I know if my video has a widescreen aspect ratio?

Measure your video's width and height in pixels, then divide width by height. If the result is approximately 1.78 (or exactly 16:9), you have widescreen PAR. For example, a 1920×1080 image yields 1920 ÷ 1080 = 1.78, confirming widescreen. You can also check your camera's or video editor's project settings, which typically display PAR as a ratio (16:9, 4:3) or decimal (1.78, 1.33). Metadata embedded in video files also contains PAR information.

Should I worry about pixel aspect ratio for social media?

No. Facebook, Instagram, TikTok, and YouTube all assume square pixels (1:1 PAR). Your camera, phone, or editing software defaults to square pixels. PAR only matters when working with legacy video formats, broadcast workflows, or specialized broadcast delivery. If you're creating content exclusively for web and social platforms, pixel aspect ratio has no impact on your workflow.

What's the difference between aspect ratio and pixel aspect ratio?

Image aspect ratio describes the overall frame dimensions (width:height), while pixel aspect ratio describes individual pixel proportions. A 1920×1080 image has an image aspect ratio of 16:9 with square pixels (1:1 PAR). A DV-NTSC video file might also display at 16:9 overall, but use 10:11 pixel aspect ratio, meaning the individual pixels are slightly taller than they are wide. The calculator resolves PAR; for overall frame ratios, consult an image aspect ratio tool.

How do I correct PAR distortion in existing video?

Most professional video editors (Premiere Pro, Final Cut Pro, DaVinci Resolve) allow you to specify the source footage's PAR in the project settings or import dialog. Once you declare the correct PAR, the software automatically interprets pixels correctly during playback and export. If you export without specifying PAR, you're essentially baking distortion into the file. Always check your editor's sequence settings and confirm they match your footage's native PAR before beginning color grading or effects work.

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