What Is Apsect Ratio and How to Change Video Output Aspect Ratio?

Diana Joan

Jan 10, 2017 04:55 am / Posted by Diana Joan

What is aspect ratio?

The aspect ratio of an image describes the proportional relationship between its width and its height. It is commonly expressed as two numbers separated by a colon, as in 16:9. For an x:y aspect ratio, no matter how big or small the image is, if the width is divided into x units of equal length and the height is measured using this same length unit, the height will be measured to be y units. In, for example, a group of images that all have an aspect ratio of 16:9, one image might be 16 inches wide and 9 inches high, another 16 centimeters wide and 9 centimeters high, and a third might be 8 yards wide and 4.5 yards high. The table below shows the most common aspect ratios.

Aspect Ratio





Standard Channels

Old TVs



HD Channels

The majority of HDTVs



Most movies

Very few TVs

Why need to change video aspect ratio?

Most televisions and computer monitors currently available have an aspect ratio of 16:9, which offers a perfect fit for high definition television shows. However, movies are usually filmed with a ratio of 21:9, which will result in black bars at the top and bottom of the picture when it is displayed on the average TV. The following picture shows black bars look like on TVs with different aspect ratio:

Black bars look like on TVs with different aspect ratio

In addition, some TV shows or TV broadcasts may have a conversional 4:3 aspect ratio, when you watch a conversional 4:3 program on your 16:9 widescreen TV, the difference in shape between those two ratios can also result in a "Pillar boxed" picture - one with black columns standing to the left and right of the image.

How to change video aspect ratio?

To avoid aspect ratio , you can do the following things:

- Get to know your TV's aspect ratio controls. Today's TVs generally have a dedicated button on the remote that lets you quickly cycle through your options. Since the aspect ratio of the programming you're watching can change frequently - when you change the channel, for example, or even when a new show begins on the same channel - you should get comfortable using these controls to get the picture to your liking.

- Set up your video sources. Go to the picture settings on your TV menu and set it to the proper aspect ratio that adapts with your TV aspect ratio. The specific terms used in these menus differ, but for a widescreen TV you'll likely see something called "widescreen" or "16:9," for example.

Set video source in TV Picture Settings

- Change output video aspect ratio with special tool

For those people who try to watch a unmatched video on some devices such as smartphones, tablets or other programs that lacks the aspect ratio changing settings, you can use a third-party video conversion tool such as Pavtube Video Converter Ultimate for Windows/Mac (best video converter review) to fix the incompatible aspect ratio issues between your video source and the devices.

As a perfect aspect ratio converter, the program can comprehensively convert virtually any digital video (H.265/HEVC, MXF, XAVC/XAVC S, Prores, AVCHD video) with the resolution of 4K/2K/HD/SD and also commercial Blu-ray/DVD disc with complicated copy protection and region codec to any of your desired output apsect ration including 16:10, 16:9, 5:4, 4:3, 3:2 and 2:1. You can also choose to keep original apsect ratio if you don't want to change the output aspect ratio.

Besides changing video output aspect ratio, you can also use the program to do other simple video editing work such as trimming or cutting video to remove unwanted parts or segments, cropping video to remove the black bars or unwanted area, splitting large video into small clips by file size, count or length, merging separate video into one file, deinterlacing interlaced video into progressive form, flip or rotate video to change its displaying angel, etc.

Step by Step to Change Video Output Aspect Ratio

Step 1: Import video or load Blu-ray/DVD disc into the program.

Start the program on your computer, click "File" > "Add Video/Audio" to import digital file formats into the program, for load Blu-ray or DVD disc, insert your DVD disc into your computer's optical drive and your Blu-ray disc into an external Blu-ray drive, click "File" > "Load from Disc" to load Blu-ray/DVD disc into the program.

Load video/Blu-ray/DVD video

Step 2: Choose output file format.

Click "Format" bar, from its drop-down option, select one of your device playable file formats. Here, we chose to select one of the popular device compatible file formats "H.264 HD Video(*.mp4)" under "HD Video" main category.

Output one of the common file formats

Step 3: Change output video aspect ratio.

Select an item on the main interface to activate the "Video Editor" function, then click the pencial like icon on the top tool bar to open the "Video Editor" window, navigate to and click the "Crop" tab, in the right panel of the program, click to switch to advanced mode. Click the "lock" icon to enable "Keep Ratio" option, to keep original aspect ratio, make sure the "Display aspect ratio" and the "Size (pix)" in "Settings" option are all set as "Original". If you want to keep the cropped aspect ratio, Pavtube software offers several aspect ratios for you to choose from, including 16:10, 16:9, 5:4, 4:3, 3:2, and 2:1.

Change output video aspect ratio

Once you selected a "Display aspect ratio", the "green crop frame" will keep this ratio to crop video and you are able to preview the final effect in real time. For example, if you want to export a file with "3:2" aspect ratio, firstly, you choose "3:2" in "Display aspect ratio", and then go to "Settings" section to adjust the Video "Size(pix)" as 720x480 or 1440x960.

After finished, click "OK" to confirm.

Go to setting window

Change output resolution as 3:2

Set output resolution as 3:2

Step 4: Start video output aspect ratio conversion process.

After all settings is completed, hit right-bottom "Convert" button to begin to produce your your desired output video aspect ratio. Then you will have no aspect ratio issue when playing the video on your desired devices.

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