Aspect ratio calculator
Reduce 1920 × 1080 to its ratio (16:9) and find the matching height or width when you scale to, say, 1280 px.
- Runs in your browser
- No upload
- Instant result
Assumptions & formula
Formula and assumptions
w/gcd(w,h) : h/gcd(w,h); h₂=w₂h₁/w₁
Results
Enter values and press Calculate to see the result here.
How to use this calculator
- Set inputs and units
Enter the original width and height as whole pixels, and choose which new side stays fixed.
- Calculate
Check this worked example: 1920×1080 → 16:9; target width1280 → height720 px
- Results
Compare the exact scaled size with the rounded pixels. Rounding can cause a small difference in the ratio.
Questions and limits
Does it resize my image?
No. It only calculates dimensions. Apply those numbers in an actual image or video resize tool.
Which input errors should I correct?
The original sides must be positive integers ≤10⁹ and the target must be positive. A zero dimension can't define a ratio.
What does this calculation leave out?
Assumes square pixels. There is no cropping, DPI interpretation, anamorphic video or file encoding.