Free Aspect Ratio Calculator Online – Resize Width or Height Proportionally
Find a missing width or height that preserves the original aspect ratio
Features
- Calculate missing width or height
- Simplified aspect ratio (e.g. 16:9)
- Works for images, video, and screens
- Free, browser-based
- No signup required
Frequently Asked Questions
No — enter only one of them (new width or new height) and the tool computes the other to keep the same proportions.
It's the original width and height reduced to their simplest whole-number form, such as 16:9 or 4:3.
Yes — it works for any content where you need to resize while keeping the original proportions, including video, images, and screen resolutions.
Resizing without matching the original ratio stretches or squashes the content, which is why designers and video editors calculate the exact matching dimension instead of guessing.
No — enter any dimensions, from small thumbnails to large print or video resolutions.
How to Use Aspect Ratio Calculator
Using Aspect Ratio Calculator is simple and free. No sign-up required.
- Enter the original width and height.
- Enter either a new width or a new height (not both).
- Click 'Calculate' to get the missing dimension and simplified ratio.
About Aspect Ratio Calculator
Aspect Ratio Calculator finds a missing width or height that preserves an image, video, or screen's original proportions, along with the simplified ratio (like 16:9 or 4:3). It's useful when resizing an image or video for a new layout and you need the new dimensions to avoid stretching or squashing the content — enter just one new dimension and the other is calculated automatically to match.
All iLoveToolZone tools work directly in your browser — no software installation or account required.