Shape comparison
Aspect Ratio Comparison Tool
Compare familiar and custom screen shapes without pretending that diagonal, height, and width mean the same thing. Switch the matching rule to see the difference that matters for your desk or content.
Compare two screen shapes
Choose what stays equal before judging the result. The same diagonal, height, and width answer three different questions.
A · 16:9
1.778:1
B · 21:9
2.333:1
B width at same height
+31.3%
B area at same diagonal
-15.3%
A wider ratio is not automatically a larger screen. At the same diagonal it can be wider, shorter, and even have less visible area.
The same diagonal can produce a different screen
A 34-inch ultrawide and a 34-inch 16:9 display share a diagonal, but they do not share a height, width, or visible area. The ultrawide stretches farther across the desk and gives up vertical space. That is why diagonal-only comparisons often feel wrong once the screen shape changes. Use the same-diagonal view when you are comparing product labels, then switch to same height to understand the actual desk footprint.
Pick the matching rule that fits the question
Same diagonal is useful for shopping because screen sizes are sold by diagonal. Same height is better when you want to know how much extra horizontal room an ultrawide adds next to a standard monitor. Same width answers the opposite question: how much vertical space do you lose or gain inside a fixed desk opening? None of these views is universally correct. The useful one is the view that keeps your real constraint fixed.
16:9, 16:10, and 21:9 on a desk
For everyday monitors, 16:9 is the compatibility baseline. A 16:10 panel keeps nearly the same width while adding a little vertical room, which is useful for documents, code, and browser work. A 21:9 screen makes a much bigger horizontal move and is better suited to timelines, two-window layouts, and supported games. It is not simply a larger 16:9 monitor, so compare the height before assuming the upgrade will feel bigger in every direction.
Black bars and cropping are content problems, not size problems
When the content ratio and screen ratio do not match, the player has to leave empty space, crop the image, or stretch it. A 16:9 video on a 21:9 monitor normally leaves bars at the sides unless software uses that space for controls. A cinema-format movie may fit the ultrawide better. Comparing the shapes first helps you predict the tradeoff, but it does not guarantee that every app or game supports the wider format.
Custom ratios are useful for unusual displays and layouts
Custom input is handy for digital signage, LED walls, older handhelds, split-screen layouts, and panels whose marketing name rounds the real ratio. Enter the horizontal and vertical parts as whole numbers when possible. The tool keeps the proportion exactly as entered, so 64:27 and 21:9 can be compared rather than treated as identical. For physical width and height in inches or centimeters, use the screen size calculator after choosing the correct ratio.
FAQ
Is 21:9 always larger than 16:9?
No. At the same diagonal, 21:9 is wider but shorter and can have less visible area. At the same height, it is wider and therefore larger.
What is the best way to compare 16:9 and 21:9 monitors?
Start with the same diagonal to match product labels, then use the same height to see the extra desk width. Check resolution separately because shape alone does not determine sharpness.
Is aspect ratio the same as resolution?
No. Aspect ratio describes shape, while resolution counts pixels. Different resolutions can share the same aspect ratio.
Can I compare a custom aspect ratio?
Yes. Choose Custom ratio and enter the horizontal and vertical values for either side. Values from 1 to 100 are supported.
Does this tool change or upload any files?
No. It compares proportions in your browser and does not need an image, account, or upload.