Aspect Ratio Calculator Free - Width & Height Online

About this tool

Scaling images and videos while maintaining proportions - without stretching or cropping - requires knowing the ratio relationship. This calculator finds the exact missing dimension so resized content always looks correct.

Enter any width and height to calculate the aspect ratio. Or enter one dimension and a target ratio to find the missing dimension - useful for scaling images, videos, and layouts proportionally.

How to use Aspect Ratio Calculator

1. Step 1: Enter Ratio. Type the width and height ratio, for example 16 and 9 for 16:9 widescreen.
2. Step 2: Enter One Dimension. Add either the target width or height and leave the other blank.
3. Step 3: Calculate. The tool fills in the missing dimension while maintaining the exact ratio.
4. Step 4: Copy Result. Use the calculated dimensions in your design, video export, or image editor.

Where this tool helps

Find the correct height for an image scaled to a specific width, verify that a resized video maintains the original aspect ratio, calculate thumbnail dimensions for different social media platforms, scale a design layout to different screen sizes, find the correct crop dimensions for a specific aspect ratio, and calculate dimensions for printing a digital image at a specific physical size.

• Calculates aspect ratio from width and height in the simplified form (e.g., 16:9, 4:3).
• Calculates missing width or height from a given ratio and one known dimension.
• Shows common equivalent ratios and identifies standard format names (16:9 = HD video).

The most common question is what 16:9 means. It means for every 16 units of width, the height is 9 units - the proportional relationship stays constant regardless of actual pixel dimensions. A 1920×1080 display and a 640×360 display are both 16:9 because 1920÷9 = 1080÷... actually because 1920/1080 = 16/9.