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How to use
Aspect ratio describes the proportional relationship between width and height without fixing an absolute size. Derive a ratio such as 16:9 from two dimensions, or lock a known ratio and solve the missing resize dimension without stretching the content.
- Choose whether to derive a ratio or solve a resize dimension.
- Enter width and height, or enter the ratio parts and the one dimension you already know.
- Read the simplified ratio and decimal form or the proportional resized dimensions.
How it is calculated
Example
1920 × 1080 reduces to 16:9 because the greatest common divisor is 120. At the same ratio, a new width of 1280 gives height = 1280 × 9 ÷ 16 = 720. Another example: 120 × 70 simplifies by 10 to 12:7 (approximately 1.7142857), not 16:9. Keeping 12:7 while increasing width to 600 yields height 600 × 7 ÷ 12 = 350.
Important notes
Aspect ratio is not resolution or image quality: 16:9 can describe 1280×720, 1920×1080 and many other sizes. For decimal dimensions, the displayed integer ratio is a practical approximation while the decimal width/height value remains the direct reference.
Worked examples and interpreting results
An image measuring 1920×1080 has aspect ratio 16:9. Resizing its width to 1280 while preserving the ratio gives height 720. Keeping the ratio prevents stretching in one direction.
| Case | Calculation | Result |
|---|---|---|
| Width divided by height | 1920 ÷ 1080 = 16 ÷ 9 | 1.777778 |
| Height after resizing width | 1280 × 9 ÷ 16 | 720 |
How to check the result
The ratio 16:9 differs from dimensions of 16×9 pixels; a ratio does not specify size. Swapping width and height gives 9:16. Cropping may change the ratio, while proportional resizing preserves it.
Frequently asked questions
What aspect ratio is 120 by 70?
The simplified ratio is 12:7 (about 1.7143), not 16:9. At a resized width of 600, the matching height is 350.
Is 1920×1080 the same aspect ratio as 16:9?
Yes. Dividing both dimensions by 120 gives 16 and 9.
How do I resize without stretching?
Keep the ratio fixed and solve the missing dimension from the new width or height.
Can I use centimeters instead of pixels?
Yes. Aspect ratio is unitless as long as width and height use the same unit.