desktop-tv · Verified 2026-08-31 · Official source
Calculate ratios and dimensions
Aspect Ratio Calculator
Calculate a ratio from width and height, or enter a ratio and one dimension to find the missing size.
Result
16 : 9
- Decimal ratio
- 1.7778:1
- Orientation
- landscape
- Dimensions
- 1920 x 1080 px
- Nearest common ratio
- 16:9 · Exact match · 0% deviation
Quick ratios
Preset ratioPlatform presets
Choose a platform, then a placementmobile · Verified 2026-08-31 · Official source
cover · Verified 2026-09-16 · Official source
all · Verified 2026-08-31 · Official source
Popular starting points
Common aspect ratios
16:91920 x 1080Widescreen video9:161080 x 1920Vertical video4:51080 x 1350Portrait images4:31600 x 1200Photos and presentations3:21500 x 1000Camera photography1:11080 x 1080Square images
View all ratio guidesImage workflow
Need to resize or crop an image?
Set a target ratio, then crop to fill, fit to preserve the image, or pad the remaining space before exporting.
Learn the basics
Make the numbers useful
How calculation works
Divide width and height by their greatest common divisor to simplify a ratio. For 1920 x 1080, the greatest common divisor of 1920 and 1080 is 120: 1920 divided by 120 is 16, and 1080 divided by 120 is 9. You can find 120 by repeatedly applying common factors, or by using the Euclidean algorithm. A less familiar size such as 1912 x 1080 has a greatest common divisor of 8 and simplifies exactly to 239:135, even though its decimal shape is close to 16:9.
When one side is missing, use the ratio as a multiplier. At 16:9 and 1920 pixels wide, height equals 1920 x 9 / 16, or 1080 pixels. Keep full precision through the calculation and round only the final pixel value so intermediate rounding does not compound the error.
Learn how to calculate aspect ratioUnderstanding the result
A ratio names a shape, not a file size. Dimensions and resolution describe pixels, so 1280 x 720 and 1920 x 1080 can share 16:9 while delivering very different amounts of detail.
Read the aspect ratio calculation guidePixel reference
Common resolutions and their ratios
A resolution counts pixels while an aspect ratio describes frame shape. Several resolutions can therefore share one ratio, and two nearly identical decimal shapes can still have different exact ratios.
| Resolution | Ratio | Typical use |
|---|---|---|
| 1280 x 720 | 16:9 | HD video |
| 1920 x 1080 | 16:9 | Full HD screens and video |
| 2560 x 1440 | 16:9 | QHD monitors |
| 3440 x 1440 | 43:18 | Ultrawide monitors |
| 1080 x 1920 | 9:16 | Vertical phone video |
Practical choices
Where aspect ratio matters
Images and photography
Camera photos often start at 3:2 or 4:3. A destination frame may need 1:1 for a thumbnail or 4:5 for a portrait post. Crop when filling the frame matters; use padding when every edge must remain visible.
Video and displays
Most desktop video uses 16:9, while vertical platforms commonly use 9:16. Matching the destination ratio avoids unexpected bars or automatic crops, but resolution still determines how much captured detail the file contains.
Web layouts
CSS aspect-ratio reserves stable space before media loads. Combine it with explicit dimensions and object-fit so cards, previews, and embedded video keep a predictable layout across viewport sizes.
Quick answers
Frequently asked questions
Does changing aspect ratio change resolution?
No. A ratio describes the frame's shape, while resolution counts its pixels. Changing dimensions can preserve the same ratio but still raise or lower resolution.
Can two different sizes have the same aspect ratio?
Yes. Dimensions such as 1280 x 720 and 1920 x 1080 both simplify to 16:9 because width and height scale by the same factor.
Which ratio should I use for vertical video?
A 9:16 frame is the common full-screen vertical shape. Confirm the destination's current pixel and safe-area requirements before publishing.
What's the difference between 16:9 and 4:3?
16:9 is 1.778:1 and is used by modern televisions, monitors, and widescreen video. 4:3 is 1.333:1 and is closer to square. At the same height, a 16:9 frame is one third wider than a 4:3 frame.
Why are videos shot on a phone vertical?
The camera app uses the phone's orientation to encode a portrait or landscape frame. Holding the phone upright commonly produces a 9:16 output, while rotating it commonly produces 16:9 landscape.
Are 1920 x 1080 and 3840 x 2160 the same ratio?
Yes. Both simplify to 16:9. The 4K UHD frame keeps the same shape but contains 8,294,400 pixels, four times the 2,073,600 pixels in Full HD.
Why is 3440 x 1440 called 21:9 when it isn't?
The label is a convenient marketing category. 3440 x 1440 simplifies exactly to 43:18, or 2.389:1, while true 21:9 is 2.333:1, a difference of about 2.4%.
Does changing the aspect ratio reduce image quality?
It depends on the method. Cropping removes parts of the composition. Shrinking can remove fine detail, and enlarging interpolates pixels. Padding preserves the full composition, but the image may still be rescaled and re-encoded.
How do I set an aspect ratio in CSS?
Use the aspect-ratio property, such as aspect-ratio: 16 / 9. Pair it with object-fit: cover to fill and crop an image, or object-fit: contain to keep the complete image inside the frame.
What's the difference between crop, fit, and pad?
Crop fills the frame and removes overflow. Fit preserves the complete image but can leave unused space. Pad also preserves the image and fills the unused space with a chosen background.
When should I use a square 1:1 image?
A square works well for profile pictures, product thumbnails, app icons, and social posts with one centered subject. A 1080 x 1080 export is a common practical size.
How is a cinematic 2.39:1 ratio calculated?
Divide width by 2.39 to find height. A 1920-pixel-wide frame is about 803 pixels high. The shape is wider than 16:9, which is why cinematic video can show horizontal bars on a standard widescreen display.
Developer reference
Build stable media layouts
Use the CSS aspect-ratio property to reserve a predictable frame before images and video load, then pair it with explicit media dimensions where appropriate.