Free image utility
Aspect Ratio Calculator
Calculate an aspect ratio from width and height, or resize dimensions while keeping the same proportions.
Aspect Ratio
16:9
- Decimal ratio
- 1.778 : 1
- Orientation
- Landscape
- Simplified from
- 1920 : 1080
- Common format
- 16:9
Common Aspect Ratios
What is aspect ratio?
Aspect ratio describes the proportional relationship between an image's width and height. It's written as two numbers separated by a colon, like 16:9, and tells you the shape — not the size.
For example, 1920 × 1080 simplifies to 16:9, the same shape as 1280 × 720 or 3840 × 2160.
How to calculate aspect ratio
Divide the width and height by their greatest common divisor (GCD) — the largest number that divides both evenly. For 1920 × 1080 the GCD is 120:
1920 ÷ 120 = 16 1080 ÷ 120 = 9 1920:1080 = 16:9
To resize while keeping that ratio, multiply the new width by the original height ÷ width: 1280 × 1080 ÷ 1920 = 720.
Common aspect ratios
| Ratio | Common uses |
|---|---|
| 1:1 | Square images, profile graphics |
| 4:3 | Photography, older displays, presentations |
| 3:2 | Photography |
| 16:9 | Video, displays, YouTube |
| 16:10 | Computer displays |
| 21:9 | Ultrawide displays |
| 9:16 | Stories, Reels, Shorts, TikTok |
| 4:5 | Portrait social images |
Frequently asked questions
What is the aspect ratio of 1920×1080?
1920×1080 is 16:9. Both numbers divide by their greatest common divisor, 120, giving 16 and 9.
How do I calculate aspect ratio?
Find the greatest common divisor (GCD) of the width and height, then divide both by it. The two results are the simplified ratio.
What is a 16:9 aspect ratio?
16:9 means the width is 16 units for every 9 units of height — about 1.78 times wider than tall. It's the standard shape for HD video and most modern screens, such as 1280×720, 1920×1080 and 3840×2160.
How do I resize an image without changing its aspect ratio?
Change one dimension and scale the other by the same factor: new height = new width × original height ÷ original width. Use Resize by Ratio above to do this automatically.
Is aspect ratio the same as resolution?
No. Resolution is the pixel count (for example 1920×1080), while aspect ratio is only the shape (16:9). 1280×720 and 3840×2160 have different resolutions but the same aspect ratio.
What aspect ratio is 1080×1350?
1080×1350 is 4:5. The GCD is 270, and 1080 ÷ 270 = 4, 1350 ÷ 270 = 5. It's a common portrait shape for social images.