Aspect Ratio Calculator

About Aspect Ratio Calculator

Aspect ratio is width:height. 16:9 is the most common for monitors and TVs. 4:3 was the old TV standard.

How to use this calculator

1. Enter the width and height of your display or image.
2. The calculator computes the aspect ratio using \(ratio = \frac{width}{height}\).
3. If needed, use the result to convert to a standard ratio format like \(16:9\) or to compare two screens.
4. Check whether you want the exact decimal ratio or the simplified whole-number ratio.

The formula explained

The formula \(ratio = \frac{width}{height}\) finds how many units wide the display is for each 1 unit of height. For example, a width of \(1920\) and a height of \(1080\) gives \(ratio = \frac{1920}{1080} \approx 1.78\), which matches \(16:9\).

• ratio = the aspect ratio, usually written as a decimal or as two whole numbers separated by a colon
• width = the horizontal size of the display or image
• height = the vertical size of the display or image

Step by step method

1. Measure or note the width and height in the same units.
2. Divide the width by the height to get the decimal aspect ratio.
3. If you want a whole-number ratio, simplify the pair of numbers to the smallest equivalent form.

Worked example

Problem. A video frame is \(1280\) pixels wide and \(720\) pixels tall. What is its aspect ratio?

1. Use the formula \(ratio = \frac{width}{height} = \frac{1280}{720}\).
2. Compute the decimal value, \(\frac{1280}{720} \approx 1.78\).
3. Simplify the ratio \(1280:720\) by dividing both numbers by \(80\), giving \(16:9\).

Tips and common mistakes

• Make sure width and height use the same units, because mixing units will give a wrong ratio.
• If the decimal looks close to a common standard such as \(4:3\), \(16:9\), or \(21:9\), compare the simplified ratio to confirm.

Frequently asked questions