Image Size Tools
Private & free

Aspect Ratio Calculator

100% Free

Simplify a width-to-height ratio and calculate a missing width or height for images, video, screens, and layouts.

  • No Sign-up
  • Instant Results
  • No Upload Needed

Original dimensions

Find and scale a ratio

Enter the current width and height, then choose which new dimension you already know.

Dimension to set

Common starting sizes

  • Simplify Any Ratio

    Reduce pixel dimensions to the smallest whole-number ratio.

  • Find a Missing Side

    Set a new width or height and calculate the matching dimension.

  • Instant Math

    Calculations run immediately in your browser without an upload.

  • No Data Sent

    The values stay on this device while you calculate.

Common aspect ratios

1:1Square posts and profile images
4:3Classic photos and presentations
3:2Photography and print formats
16:9HD video and widescreen images
4:5Portrait social posts
9:16Stories, Reels and vertical video

Already have an image? Check its current dimensions or crop it to a common ratio.

Frequently Asked Questions

How do I calculate an aspect ratio?

Divide the width and height by their greatest common divisor. For 1920 x 1080, the divisor is 120, so the simplified ratio is 16:9.

How do I find the height for a 16:9 image?

Multiply the new width by 9 and divide by 16. A width of 1280 gives a height of 720 pixels.

Does an aspect ratio have to use pixels?

No. A ratio describes proportions, so you can use pixels, inches, centimeters, or any other unit as long as the width and height use the same unit.

Will this calculator resize my image file?

No. It calculates dimensions only. Use the linked Resize Image tool when you want to create and download a resized file.