Video aspect ratio calculator

What is an aspect ratio?

It is the proportion of a frame's width to its height, written as two numbers. A 1920 by 1080 frame is 16:9 because both sides divide by 120 to give 16 and 9. The ratio stays the same when you scale a video, as long as width and height change together.

The calculator finds the greatest common divisor of your two numbers and divides both by it.

Which ratios do creators use most?

How do you resize without stretching?

Pick the new width, then calculate the height from the same ratio: new height = new width × original height ÷ original width. If the answer is not a whole number, round it, and prefer an even number because many encoders need even dimensions.

• Crop or pad to change the ratio; scaling alone only changes size.
• Never stretch the picture to fill a frame. People look wrong when you do.
• Keep key content inside the safe area when you crop wide footage to vertical.

What goes wrong most often?

• Mixing up width and height, so a vertical video is built as horizontal.
• Exporting vertical video inside a widescreen frame, which leaves black bars.
• Using an odd height that the encoder rejects.