Aspect ratio is the proportion of a screen or image's width to its height, written as two numbers such as 16:9 or 4:3. It describes the shape, not the size. A 16:9 screen is 16 units wide for every 9 units tall, giving the widescreen shape used by most modern monitors, TVs, and videos.
Why this happens
Aspect ratio exists because screens and images can be made in different shapes. Common ones include 16:9 for most TVs and monitors, 4:3 for older screens, 21:9 for ultrawide monitors, and various ratios for phone screens and photos. Content is created for a certain ratio, and screens are built to a certain ratio.
When the content's ratio does not match the screen's ratio, the device has to add black bars, stretch the image, or crop it to make it fit.
Is this normal?
Yes. Different aspect ratios are completely normal and standard. Seeing black bars above and below a movie, or on the sides of an old show, is the normal way of fitting one ratio onto a screen with a different ratio.
Does it cause any problems?
Aspect ratio itself causes no problems, but a mismatch can. Forcing content to fill a differently shaped screen can stretch faces and objects so they look too wide or too tall, or crop out part of the picture. Matching the ratio, or accepting black bars, keeps the image correct.
How to fix or check it
- To check your screen's ratio, divide its pixel width by its height. For example, 1920 by 1080 simplifies to 16:9.
- If the picture looks stretched, open the display's aspect or picture size menu and set it to a mode like Normal, Original, or Aspect rather than Full or Stretch.
- On a computer, set the resolution to the screen's native value so the ratio matches and the image is not squashed.
- On a TV, use the picture size or zoom setting to switch between filling the screen and keeping the original shape.
- In video players, choose the aspect setting that keeps the original proportions if faces or objects look distorted.
- Accept black bars when content and screen ratios differ, since they preserve the correct shape of the image.
Frequently asked questions
What is the most common aspect ratio?
16:9 is the most common today, used by most monitors, TVs, laptops, and online video. Older screens and content often use 4:3, and ultrawide monitors use 21:9.
Why does my video have black bars?
Black bars appear when the video's aspect ratio does not match your screen's. They fill the extra space so the picture keeps its correct shape instead of being stretched or cropped.
Should I stretch content to fill the screen?
Usually no. Stretching a different ratio to fill the screen distorts the image so people and objects look too wide or tall. Keeping the original ratio, even with black bars, looks correct.