How to Use Our Pixel Aspect Ratio Calculator
To calculate the PAR, you need to know how your video is stored and how it’s supposed to be displayed. This information can be found using video analysis tools like MediaInfo or VLC Media Player.
Storage Aspect Ratio (SAR) Width & Height: These are the actual pixel dimensions of your video file. For example, a standard DV NTSC video file has a resolution of 720×480 pixels. You would enter 720 for the SAR Width and 480 for the SAR Height.
Display Aspect Ratio (DAR) Width & Height: This is the aspect ratio your video is intended to be viewed at. For example, if the 720×480 video is meant to fill a standard widescreen (16:9) TV screen, you would enter 16 for the DAR Width and 9 for the DAR Height.
Understanding Your Results: The Shape of a Pixel
The result of this calculation is the Pixel Aspect Ratio (PAR). It’s a number that represents the shape of a single pixel in your video.
Think of it this way: We assume all pixels are perfect little squares. But in many older video formats, to save space or conform to broadcast standards, the pixels were actually rectangular.
A PAR of 1:1 (or just “1.0”) means the pixels are square. This is the standard for all modern HD and 4K video, computers, and the web.
A PAR other than 1:1 (e.g., 10:11 or 40:33) means the pixels are rectangular (non-square). This tells the video player, “The pixels in this video are slightly wider or taller than they are stored. Please stretch them accordingly during playback to make the image look correct.”
The Relationship: SAR x PAR = DAR
The fundamental formula connecting these three concepts is:
Storage Aspect Ratio (SAR) × Pixel Aspect Ratio (PAR) = Display Aspect Ratio (DAR)
Our calculator isolates the PAR using this relationship:
PAR=SARDARorPAR=(SAR Width/SAR Height)(DAR Width/DAR Height)
Getting the PAR right is the technical key to making a video stored with one set of dimensions (like 720×480) display correctly in its intended shape (like 16:9 widescreen).
Analogy: Laying Floor Tiles
Square Pixels (Modern HD): Imagine tiling a room with perfect square tiles (1ft x 1ft). The shape of the tiled area is exactly what you’d expect. A 16ft by 9ft area is a 16:9 rectangle.
Rectangular Pixels (Older SD): Now imagine your tiles are rectangular (e.g., 1ft wide but only 0.9ft tall). If you lay 16 of these tiles across and 9 tiles down, the area is no longer a perfect 16:9 rectangle. The PAR is the “correction factor” needed to tell someone how to view your rectangular-tiled floor so it looks like the intended shape.
This correction is exactly what happens when you see a stretched circle in a video suddenly snap into a perfect circle during playback.
Frequently Asked Questions About Pixel Aspect Ratio
### What is the difference between PAR, DAR, and SAR?
These three terms work together to define a video’s shape. It’s the most common point of confusion in video encoding.
In short: The grid of pixels (SAR) is made up of individual pixel shapes (PAR), which combine to create the final image shape (DAR).
Why do non-square pixels even exist?
Non-square pixels were an ingenious engineering solution to problems of the analog and early digital eras.
Broadcast Standards: Analog television standards (like NTSC and PAL) had fixed scanning frequencies. To digitize these signals, engineers had to sample them at a specific rate. This resulted in resolutions like 720×480 (for NTSC) and 720×576 (for PAL), which don’t naturally simplify to 4:3 or 16:9. Non-square pixels were invented to map these digital resolutions back to the standard analog display shapes.
Saving Bandwidth/Data: In the early days of digital video, data storage and bandwidth were extremely expensive. Anamorphic formats used non-square pixels to “squeeze” a widescreen (16:9) image into a standard 4:3 data stream (like on a DVD). This was more efficient than creating a whole new widescreen broadcast system.
What is anamorphic video?
Anamorphic video is any video that uses non-square pixels to change its display shape. The most common example is DVD video. A widescreen movie on a DVD is often stored as a 720×480 file (a 3:2 SAR). The file is flagged with a PAR of approximately 1.21 (or 40:33 for NTSC).
During playback, the DVD player reads this flag and horizontally stretches the 720 pixels by a factor of 1.21. This “de-squeezes” the image into its proper 16:9 widescreen shape. Without the correct PAR flag, the movie would look vertically squashed.
How do I fix a video that looks stretched?
If your video is playing back incorrectly, it’s because the PAR flag is either wrong or missing. You need to use software to “re-flag” the file without re-encoding it, which is very fast.
Step-by-Step Guide using HandBrake (a free tool):
Open your source video file in HandBrake.
Go to the “Dimensions” tab.
You will see options for “Anamorphic”. Instead of “Automatic,” choose “Custom”.
Uncheck “Pillarbox/Letterbox” to ensure no black bars are added.
In the “Pixel Aspect Ratio” fields, manually enter the correct PAR you found with our calculator. For example, for NTSC 16:9, you might enter 40:33.
Set the encoding quality to a high setting (like Constant Quality RF 18) and start the encode. This will create a new file with the correct PAR flag embedded.
Do I need to worry about PAR for modern HD or 4K video?
No, not for new footage. Any video you shoot on a modern camera, smartphone, or screen recorder will use a PAR of 1:1 (square pixels). Resolutions like 1920×1080 (HD), 3840×2160 (4K UHD), and 1280×720 (HD) all have a native 16:9 SAR and use square pixels. The concept of PAR is primarily a legacy issue you’ll encounter when digitizing old tapes (VHS, MiniDV) or ripping old DVDs.
What is the PAR for standard definition (SD) video?
The exact PAR values can vary slightly by system, but these are the industry standards defined by the SMPTE.
How do I find the SAR and DAR of my video?
The easiest way is with a free program called MediaInfo. Simply open your video file with the program, and it will give you a detailed report.
SAR: Look for “Width” and “Height.”
DAR: Look for “Display aspect ratio.”
PAR: Look for “Pixel aspect ratio.” If the file is playing incorrectly, the DAR or PAR values shown in MediaInfo are likely wrong.
A Concrete Example: NTSC Widescreen
Let’s walk through the math for a standard anamorphic widescreen video from a MiniDV tape.
You know it was stored at DV NTSC resolution, so its SAR is 720×480.
You know it was shot in widescreen, so its intended DAR is 16:9.
Plug these into the calculator or formula:
This decimal is close to the official SMPTE standard PAR of 40:33 (~1.21). The small difference is due to historical conventions around “clean aperture.” For all practical purposes, you would set the PAR to 40:33 in your software to fix the video.
Can PAR affect JPEG images?
Generally, no. The vast majority of still image formats, including JPEG, PNG, and GIF, exclusively use a 1:1 square pixel aspect ratio. The concept of non-square pixels is almost entirely unique to the world of standard-definition digital video.
How does PAR work with YouTube?
Modern platforms like YouTube and Vimeo are very sophisticated. When you upload a video, their servers analyze it. If they detect a non-square PAR flag, they will automatically transcode the video into a new file with square pixels (e.g., converting a 720×480 anamorphic file into a 854×480 square-pixel file). While this usually works, providing a file with the correct PAR flag beforehand ensures that YouTube interprets it correctly from the start, avoiding any potential errors in processing.
Now that you understand the shape of your pixels, you may want to calculate the display dimensions of your final video. Head over to our Aspect Ratio Calculator to work with final screen sizes. If you are encoding these files, use our Video File Size Calculator to estimate how large the corrected file will be.
