What Is a Screen Resolution Calculator?
This calculator takes a display's pixel width and height and works out its simplified aspect ratio, total megapixels, and — with a diagonal size — its pixel density in PPI (pixels per inch).
These numbers are useful when buying a monitor or TV, comparing camera and screen resolutions, or checking whether a video will fit a display without letterboxing.
How to Read Your Results
Aspect Ratio
The width-to-height ratio in its simplest form, like 16:9 or 21:9. This determines whether content will show letterboxing (black bars) on a given screen.
Megapixels
The total pixel count in millions — the same unit used for camera sensors, letting you compare a display's resolution directly against a photo's.
PPI (Pixels Per Inch)
How densely packed the pixels are. Higher PPI means a sharper image at a given viewing distance, especially noticeable on small screens like phones.
Real-World Example
A common 24-inch 1080p monitor:
| Resolution | Aspect Ratio | Megapixels | PPI (at 24") |
|---|---|---|---|
| 1920 × 1080 | 16:9 | 2.07 MP | ≈92 PPI |
| 2560 × 1440 | 16:9 | 3.69 MP | ≈122 PPI |
| 3840 × 2160 (4K) | 16:9 | 8.29 MP | ≈184 PPI |
The same 24-inch panel gets noticeably sharper as resolution climbs from 1080p to 4K — nearly double the PPI, and roughly 4× the total pixels.
Tips for Comparing Screens
- Higher PPI matters more up close — phones and laptops benefit more from high PPI than a TV viewed from across a room.
- Match aspect ratio to your content to avoid letterboxing when watching video or gaming.
- Compare megapixels, not just resolution names, since "4K" and "1440p" are marketing shorthand for specific pixel counts.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team