Aspect Ratio Calculator
Find the aspect ratio of any width × height, and calculate a new dimension that keeps the same ratio when resizing.
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Original dimensions
16:9
aspect ratio
Resize keeping this ratio
Working with aspect ratios
What an aspect ratio is
An aspect ratio is the proportional relationship between width and height, written as two numbers like 16:9 or 4:3. It stays the same no matter the actual pixel size, which is why it's the reliable way to keep images and videos from being stretched.
Resizing without distortion
When you change one dimension, the other must scale by the same factor to keep the ratio. Enter a new width and the calculator gives the exact height that avoids stretching — handy for fitting images into a layout, thumbnail, or video frame.
Frequently asked questions
What does 16:9 mean?
For every 16 units of width there are 9 of height — the standard widescreen video and display ratio.
How do I keep the ratio when resizing?
Enter your original width and height, then a new width — the tool returns the height that preserves the ratio.
Does this need an image?
No — it's a pure calculator. Just type the numbers.
Is anything uploaded?
No. Everything is computed locally in your browser.