Aspect Ratio Calculator
Calculate image or video aspect ratio and resize width or height proportionally without stretching. Useful for screens, photos, video and design.
Calculator workspace
Enter your values, calculate, then review the assumptions shown with the result.
How this calculator helps
Calculate image or video aspect ratio and resize width or height proportionally without stretching. Useful for screens, photos, video and design. The calculator keeps the main answer with supporting values and the formula or method so the result is easier to check, compare and save.
Aspect ratio and proportional resizing
An aspect ratio describes the relationship between width and height. A 1920 × 1080 image simplifies to 16:9. When the width changes, the height must change by the same scale factor to avoid stretching or squeezing the picture.
This calculator accepts any positive dimensions. Choose whether you know the new width or the new height, enter that target dimension, and it calculates the matching other dimension. It also shows the decimal ratio and a simplified integer ratio when the original dimensions are whole numbers.
Common uses
Aspect-ratio calculations are useful for social media graphics, video frames, website images, projector screens, digital signage, print layouts and screenshots. The arithmetic is the same even when the units are pixels, centimetres or inches, as long as width and height use the same unit.
Example: 1920 × 1080 to 1280 pixels wide
The ratio 1920/1080 is 1.777777…, or 16:9. Setting the new width to 1280 gives a height of 720. That is why 1280 × 720 and 1920 × 1080 share the same widescreen aspect ratio.
Cropping is different from resizing
Proportional resizing preserves the whole image. Cropping removes some content to fit a different ratio. If your destination requires a square 1:1 image but the source is 16:9, you cannot preserve both the entire image and the target ratio without adding blank space or cropping.
How to use it well
- Use values from the source that actually applies to your situation.
- Check units, dates, rates and percentages before calculating.
- Review the formula/method and supporting figures rather than relying only on the headline number.
- For changing rates, regulations or policies, verify the current official source before an important decision.
- Use Copy Result or Save Result Image to keep the assumptions with the answer.
Frequently Asked Questions
How do I calculate aspect ratio?
Divide width by height. For whole-number dimensions, the calculator also reduces them to a simplified ratio such as 16:9.
How do I resize without distortion?
Keep the width-to-height ratio constant and calculate the missing dimension from the new width or height.
Can I use centimeters instead of pixels?
Yes. Use any unit as long as both original dimensions use the same unit.