Image & PDF
Aspect Ratio Calculator
Calculate image aspect ratio and find a missing width or height while preserving proportions.
✓ Free to use✓ No signup✓ Local processing where possible
What is Aspect Ratio Calculator?
Calculate an image or screen aspect ratio, find a missing width or height, and scale dimensions without changing proportions.
Aspect ratio formula
Aspect ratio compares width to height. Divide both values by their greatest common divisor to simplify a ratio such as 1920:1080 to 16:9.
Find a new height from width
When the ratio is fixed, use new height = new width ÷ ratio. The calculator can fill the missing dimension automatically.
Common ratios
- 16:9 — video and widescreen displays
- 4:3 — traditional displays and presentations
- 1:1 — square images
- 3:2 — common photography ratio
- 9:16 — vertical video
Avoid distorted images
Keep the same ratio when resizing an image or video unless intentional cropping is required.
Last updated: August 13, 2026
Frequently Asked Questions
How do I calculate aspect ratio?
Divide width and height by their greatest common divisor to get the simplified width:height ratio.
How do I find height from width and aspect ratio?
Divide the target width by the width-to-height ratio.
What is the aspect ratio of 1920×1080?
1920×1080 simplifies to 16:9.
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