Enter a width and height and they are reduced to the simplest ratio, so 1920 × 1080 is 16:9. If the size is not an exact standard ratio, it names the closest one and how far off it is.
Images
Aspect Ratio Calculator
Find the aspect ratio of a width and height, lock it, and change one side to get the other. Load common video, social and screen sizes with one click.
Quick guide
How to use this tool
Enter a width and height, or choose a common ratio such as 16:9 or 4:3 from the Ratio buttons. The ratio, its decimal value, the closest standard ratio and a CSS aspect-ratio line appear at once.
With the lock on, changing one side changes the other so nothing is stretched. Turn the lock off to type both sides freely, and the ratio follows them. Use Rounding to choose whether fractions of a pixel round to the nearest, up, down, or stay exact.
Read the sizes at this ratio for common widths and press Use to load one, or pick a Common size such as Instagram post or YouTube thumbnail. Copy any value with its button, or press Copy result for the ratio and size together.
How to use this tool
Enter a width and height, or choose a common ratio such as 16:9 or 4:3 from the Ratio buttons. The ratio, its decimal value, the closest standard ratio and a CSS aspect-ratio line appear at once.
With the lock on, changing one side changes the other so nothing is stretched. Turn the lock off to type both sides freely, and the ratio follows them. Use Rounding to choose whether fractions of a pixel round to the nearest, up, down, or stay exact.
Read the sizes at this ratio for common widths and press Use to load one, or pick a Common size such as Instagram post or YouTube thumbnail. Copy any value with its button, or press Copy result for the ratio and size together.
px
px
Ratio Landscape
16:9As a number
1.7778Closest standard exact
16:9, HD video, widescreenCSS
aspect-ratio: 16 / 9;Size 2.07 megapixels
1920 × 1080Sizes at 16:9
- 320 × 180
- 480 × 270
- 640 × 360
- 768 × 432
- 1024 × 576
- 1280 × 720
- 1600 × 900
- 1920 × 1080
- 2560 × 1440
- 3840 × 2160
Common sizes
What it handles
The ratio, and every size that keeps it.
An aspect ratio is the shape of a rectangle: how wide it is for its height. Keep it when you resize and nothing is stretched or squashed.
With the ratio locked, change the width and the height follows, or the other way round. Choose whether fractions of a pixel round to the nearest pixel, up, down, or stay exact.
Load HD, 4K, Instagram, story, YouTube thumbnail and header sizes in one click, and see the height at every common width for the ratio you are using.
Frequently asked questions
How do I calculate an aspect ratio?
Divide the width and the height by their greatest common divisor. For 1920 × 1080 that number is 120, so the ratio is 16:9. The calculator does this for you, including sizes with decimals.
How do I resize an image without stretching it?
Keep the aspect ratio. The new height is the new width times the original height divided by the original width. Lock the ratio here, type the new width and read the height.
What is the aspect ratio of 1920 × 1080?
16:9, the shape of widescreen video and most monitors. 1280 × 720, 2560 × 1440 and 3840 × 2160 are all 16:9 as well.
Why is my ratio close to, but not exactly, 16:9?
Some sizes are rounded to whole pixels. A 1366 × 768 screen is 683:384, within 0.1% of 16:9. The calculator shows the closest standard ratio and how far off yours is.
What does the CSS aspect-ratio line do?
aspect-ratio: 16 / 9 makes a box keep that shape as its width changes, so images, video and cards stay in proportion without padding tricks. Copy the line from the results.