1920 × 1080 = 16:9
Aspect ratio calculator
A 1920 × 1080 picture has an aspect ratio of 16:9. Enter a width and height to reduce them, or a ratio and one side to find the other.
- 1920 × 1080 = 16:9
- 16:9, width 1280 → height 720
Both blocks update as you type. When the missing side is not a whole number it is rounded to whole pixels, and the exact value is shown below it.
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At a glance
- Price
- No charge
- Account
- None needed
- Upload
- Not applicable — you type numbers, nothing is sent anywhere
- Method
- Divide both sides by their greatest common divisor
- Missing side
- Known side × other ratio term ÷ its own, rounded to whole pixels
- Limit
- Width and height in the first block must be whole numbers above zero
Common aspect ratios and sizes
The sizes come from the same function as the calculator and are rounded to whole pixels, so 21:9 and 3:2 give heights that are not exact.
| Ratio | Width ÷ height | Width 1280 | Width 1920 | Width 3840 |
|---|---|---|---|---|
| 16:9 | 1.7778 | 1280 × 720 | 1920 × 1080 | 3840 × 2160 |
| 4:3 | 1.3333 | 1280 × 960 | 1920 × 1440 | 3840 × 2880 |
| 3:2 | 1.5 | 1280 × 853 | 1920 × 1280 | 3840 × 2560 |
| 1:1 | 1 | 1280 × 1280 | 1920 × 1920 | 3840 × 3840 |
| 21:9 | 2.3333 | 1280 × 549 | 1920 × 823 | 3840 × 1646 |
| 9:16 | 0.5625 | 1280 × 2276 | 1920 × 3413 | 3840 × 6827 |
How to find an aspect ratio
Reduce a size to its ratio
Type the width and height in pixels. The calculator divides both by their greatest common divisor, so 1920 × 1080 becomes 16:9, and also shows the decimal ratio and the megapixels.
Or find the missing side
Type the ratio, for example 16 and 9, then fill in either the width or the height, never both. The other side is worked out and rounded to whole pixels.
Use the result
Copy the size into an image editor, a video export dialog or a design tool. Scaling both sides by the same factor keeps the picture from stretching.
How an aspect ratio is calculated
An aspect ratio is the width divided by the height, written as the smallest pair of whole numbers with that quotient. To find it, divide both sides by their greatest common divisor: 1920 and 1080 share a divisor of 120, which leaves 16 and 9. The decimal form is 16 ÷ 9 = 1.7778. Common ratios are 16:9 for video and most screens, 4:3 for older screens and many tablets, 3:2 for 35 mm film and many cameras, 1:1 for square posts and 9:16 for vertical video.
To find a missing side, multiply the known side by the other side of the ratio and divide by its own: a 16:9 picture 1280 pixels wide is 1280 × 9 ÷ 16 = 720 pixels high. Many ratios do not give whole pixels. A 21:9 picture 1920 wide would be 822.86 high, and the page shows 823. Rounding changes the ratio slightly, so a size that looks like 21:9 may reduce to a different pair: 3440 × 1440 reduces to 43:18, and 2560 × 1080 to 64:27.
Aspect ratio questions
What does 16:9 mean?
For every 16 units of width there are 9 units of height, so the picture is 1.7778 times as wide as it is high. 1280 × 720, 1920 × 1080 and 3840 × 2160 are all 16:9.
How do I calculate the aspect ratio of an image?
Divide the width and the height by their greatest common divisor. 1600 × 1200 has a divisor of 400, so the ratio is 4:3. If the divisor is 1 the size is already in lowest terms, which happens often for cropped photos.
How do I find the height for a given width?
Multiply the width by the ratio height and divide by the ratio width. For 16:9 and a width of 1280 the height is 1280 × 9 ÷ 16 = 720. For 4:3 and a width of 1024 it is 768.
Why does my size not reduce to exactly 16:9?
Some screens use sizes that are close to a ratio but not equal to it. 1366 × 768 is sold as 16:9, yet it reduces to 683:384 because 768 does not divide evenly into 9 parts. The decimal ratio, 1.7786, is within 0.05% of 16:9 (1.7778).
What is a 21:9 screen, really?
Ultrawide monitors are marketed as 21:9, but their sizes are slightly different: 3440 × 1440 is 43:18 (2.389) and 2560 × 1080 is 64:27 (2.370). A true 21:9 is 2.333. Widescreen cinema is about 2.39:1.
Does this calculator upload my image or my numbers?
No. You type numbers, the arithmetic runs in your browser tab and nothing is sent anywhere. It does not open an image, so it cannot read the size of a file for you.