Aspect ratio describes the proportional relationship between a screen’s or image’s width and height, independent of its actual size. This calculator takes a resolution (or any width and height in pixels) and simplifies it down to its aspect ratio, matching it against common named ratios like 16:9, 16:10, 21:9, and 4:3 wherever possible.
| Resolution | Name | Aspect ratio | Megapixels |
|---|---|---|---|
| 1280×720 | HD (720p) | 16:9 | 0.92 MP |
| 1366×768 | WXGA | 683:384 (≈ 16:9) | 1.05 MP |
| 1920×1080 | Full HD (1080p) | 16:9 | 2.07 MP |
| 2560×1080 | UW-FHD | 64:27 (≈ 21:9) | 2.76 MP |
| 2560×1440 | QHD (1440p) | 16:9 | 3.69 MP |
| 2560×1600 | WQXGA | 8:5 (16:10) | 4.10 MP |
| 3440×1440 | UWQHD (ultrawide) | 43:18 (≈ 21:9) | 4.95 MP |
| 3840×2160 | 4K UHD (2160p) | 16:9 | 8.29 MP |
≈ marks panels sold under the nearest round ratio, such as 3440×1440 (43:18) as 21:9.
How this is calculated: the formula on our Methodology page.
Quick answer
This tool reduces a width and height in pixels to the simplest whole-number ratio using their greatest common divisor, then matches it against common names like 16:9, 16:10, 21:9, and 4:3. Note that 2560×1080 simplifies exactly to 64:27, which is close to but not mathematically the same as 21:9 (64:27 approx 2.37:1 versus 21:9 approx 2.33:1).
16:9 and 21:9 Resolutions
To work out a 16:9 size, divide the width by 16 and multiply by 9 for the height (1920 wide is 1080 tall), or divide the height by 9 and multiply by 16 for the width (1440 tall is 2560 wide). Every common 16:9 resolution below simplifies exactly to 16:9. Ultrawide “21:9” monitors do not: their real ratios are a little wider, from about 2.37:1 to 2.40:1 against 2.33:1 for a true 21:9, so makers round them to the nearest familiar name.
| Resolution | Name | Sold as | Exact ratio | Width ÷ height |
|---|---|---|---|---|
| 1280 × 720 | HD (720p) | 16:9 | 16:9 | 1.78:1 |
| 1600 × 900 | HD+ | 16:9 | 16:9 | 1.78:1 |
| 1920 × 1080 | Full HD (1080p) | 16:9 | 16:9 | 1.78:1 |
| 2560 × 1440 | QHD (1440p) | 16:9 | 16:9 | 1.78:1 |
| 3200 × 1800 | QHD+ | 16:9 | 16:9 | 1.78:1 |
| 3840 × 2160 | 4K UHD | 16:9 | 16:9 | 1.78:1 |
| 5120 × 2880 | 5K | 16:9 | 16:9 | 1.78:1 |
| 7680 × 4320 | 8K UHD | 16:9 | 16:9 | 1.78:1 |
| 2560 × 1080 | UW-FHD | 21:9 | 64:27 | 2.37:1 |
| 3440 × 1440 | UWQHD | 21:9 | 43:18 | 2.39:1 |
| 3840 × 1600 | UW-QHD+ | 21:9 | 12:5 | 2.40:1 |
| 5120 × 2160 | 5K2K | 21:9 | 64:27 | 2.37:1 |
Exact ratio = width and height divided by their greatest common divisor, as in the calculator. A 16:9 screen is 1.78 times as wide as it is tall, a true 21:9 screen 2.33 times.
What the Result Means
The result is the simplest whole-number ratio that represents your width-to-height proportions, along with its common name if it matches a widely used standard. 16:9 is the standard aspect ratio for most modern TVs, monitors, and laptop screens. 21:9 and wider ratios like 32:9 describe ultrawide and super-ultrawide monitors. 4:3 was the standard for older TVs and monitors before widescreen became the norm, and it’s still used for some tablets. 16:10 shows up on certain productivity-focused monitors and laptops, offering slightly more vertical space than 16:9.
Knowing the exact aspect ratio matters when buying a monitor, choosing video export settings, cropping a photo for a specific frame, or checking whether content will display with black bars (letterboxing or pillarboxing) on a given screen.
How This Calculator Works
The calculator takes your width and height in pixels and finds their greatest common divisor (GCD), then divides both numbers by it to reduce the ratio to its simplest whole-number form.
Formula: aspect ratio = width : height, simplified by dividing both by GCD(width, height).
Worked example: Take a resolution of 1920×1080. The greatest common divisor of 1920 and 1080 is 120. Dividing both by 120 gives 1920 ÷ 120 = 16 and 1080 ÷ 120 = 9, so the simplified ratio is 16:9 — the standard widescreen ratio. Try a resolution of 2560×1080: the GCD of 2560 and 1080 is 40, giving 2560 ÷ 40 = 64 and 1080 ÷ 40 = 27, so the ratio simplifies to 64:27 — close to, but not mathematically the same as, the 21:9 ratio that resolution is commonly marketed under (64:27 ≈ 2.37:1, while 21:9 ≈ 2.33:1).
Important Limitations
Some resolutions simplify to unusual or non-round ratios (like 64:27 above) that don’t match a common marketing name exactly, even though they’re close to one — in those cases the calculator will show the precise simplified ratio and note the nearest common name, since manufacturers often round for marketing purposes. Aspect ratio also only describes proportions, not sharpness or physical size — two screens can share an identical aspect ratio while having completely different resolutions or physical dimensions.
If you’re trying to figure out how large a screen with a given ratio actually is in inches, or how a specific resolution’s pixel density compares, this tool won’t answer that directly — pair it with the Screen Size Calculator or Resolution Calculator for those numbers.
Frequently Asked Questions
What's the most common aspect ratio for monitors and TVs?
16:9 is by far the most common aspect ratio for modern TVs, laptop screens, and the majority of desktop monitors. It became the standard because it suits widescreen video content well.
What resolution counts as ultrawide?
Ultrawide monitors typically use a 21:9 aspect ratio (commonly 2560×1080 or 3440×1440), which is noticeably wider relative to its height than standard 16:9 screens. Super-ultrawide monitors go even further, often using a 32:9 ratio around 5120×1440.
Why do some resolutions not simplify to a clean-looking ratio?
Because the simplest whole-number reduction of the actual pixel dimensions doesn’t always land on a “nice” number, even when the resolution is marketed under a rounder ratio name. For example, 2560×1080 simplifies exactly to 64:27, which is close to the commonly marketed “21:9” ultrawide ratio but not mathematically identical to it (64:27 ≈ 2.37:1, versus 21:9 ≈ 2.33:1).
Does aspect ratio affect gaming or video experience?
Yes — a wider aspect ratio like 21:9 shows more of the horizontal field of view in supported games and looks more cinematic for video, but not all content and games support ultrawide ratios natively, which can result in black bars or stretched images.