Aspect Ratio Calculator
Enter a width and height to find their exact aspect ratio — the shape those dimensions describe.
Dimensions
Aspect ratio describes the shape of an image or screen — how wide it is for its height. 16:9 is standard widescreen; 21:9 is ultrawide. Any pair of dimensions works, in pixels or in any other unit.
Common resolutions
Aspect ratio
16:9
1,920 × 1,080 pixels simplifies exactly to 16:9: 16 units of width for every 9 of height. That is 16:9 — The standard widescreen video and display ratio.
Aspect ratio 16:9, landscape.
Proportion
Details
- Decimal ratio1.7778width ÷ height
- OrientationLandscape
- Total pixels2,073,600
- Megapixels2.07 MP
- Common ratio16:9Exact match
Formula and assumptions
gequalsgreatest common divisor of width and height
ratioWidthequalswidth ÷ g
ratioHeightequalsheight ÷ g
decimalRatioequalswidth ÷ height
pixelCountequalswidth × height
megapixelsequalspixelCount ÷ 1,000,000
Assumptions
- Width and height must be positive whole numbers of pixels.
- The simplified ratio is exact. A common name such as 16:9 is only shown when the dimensions simplify to it exactly, never when they are merely close.
- A ratio has no units, so the same result applies to any pair of dimensions measured in the same unit.
Common aspect ratios
| Ratio | Decimal | Where you see it |
|---|---|---|
| 1:1 | 1 | Square. Common for social posts and album art. |
| 4:3 | 1.3333 | Classic television, many cameras and tablets. |
| 3:2 | 1.5 | Standard 35 mm photography and many DSLR sensors. |
| 16:10 | 1.6 | Common on laptops and productivity monitors. |
| 16:9 | 1.7778 | The standard widescreen video and display ratio. |
| 2:1 | 2 | Univisium. Used by some films and streaming productions. |
| 64:27 | 2.3704 | The exact ratio most 21:9 ultrawide displays use. |
| 32:9 | 3.5556 | Super ultrawide. Two 16:9 displays side by side. |
Questions
What does an aspect ratio actually describe?
An aspect ratio describes the proportion between width and height, not a size. A 16:9 image is 16 units wide for every 9 units tall, whether those units are pixels, centimetres or metres.
Why is my ratio not one of the familiar ones?
Many real resolutions do not simplify to a marketing ratio. 3440 × 1440 simplifies exactly to 43:18, which is sold as 21:9. This calculator shows the mathematically exact ratio and only names a common ratio when the match is exact.
Does the unit matter?
No. A ratio is unitless. The examples here use pixels because that is the most common case, but the same simplification applies to any pair of dimensions measured in the same unit.
What is the difference between the ratio and the decimal ratio?
The simplified ratio expresses the proportion as two whole numbers, such as 16:9. The decimal ratio is width divided by height, so 16:9 becomes 1.7778. Both describe the same shape.