Screen Resolution Calculator
Enter your screen's resolution and diagonal size to calculate PPI, aspect ratio, dot pitch, and other display metrics. Or select a common resolution preset below.
Common Screen Resolutions
Reference table showing popular display resolutions, their typical screen sizes, and calculated PPI values.
| Name | Resolution | Aspect Ratio | Typical Size | PPI | Megapixels |
|---|---|---|---|---|---|
| HD (720p) | 1280 x 720 | 16:9 | 15.6" | 94 | 0.92 |
| Full HD (1080p) | 1920 x 1080 | 16:9 | 24" | 92 | 2.07 |
| QHD (1440p) | 2560 x 1440 | 16:9 | 27" | 109 | 3.69 |
| 4K UHD | 3840 x 2160 | 16:9 | 27" | 163 | 8.29 |
| 5K | 5120 x 2880 | 16:9 | 27" | 218 | 14.75 |
| 8K UHD | 7680 x 4320 | 16:9 | 32" | 275 | 33.18 |
| WUXGA | 1920 x 1200 | 16:10 | 24" | 94 | 2.30 |
| WQXGA | 2560 x 1600 | 16:10 | 13.3" | 227 | 4.10 |
| Ultrawide QHD | 3440 x 1440 | 21:9 | 34" | 109 | 4.95 |
| Ultrawide 4K | 3840 x 1600 | 12:5 | 38" | 109 | 6.14 |
| XGA | 1024 x 768 | 4:3 | 15" | 85 | 0.79 |
| SXGA | 1280 x 1024 | 5:4 | 17" | 96 | 1.31 |
Understanding PPI Quality Categories
The sharpness of a display depends on both its resolution and physical size. Here is how PPI ranges typically map to perceived quality:
| Category | PPI Range | Typical Use | Perception |
|---|---|---|---|
| Low | Below 100 | Large desktop monitors, TVs | Individual pixels may be visible at close range. Fine for TV viewing distance. |
| Medium | 100 -- 199 | Standard desktop monitors, laptops | Good clarity for normal desktop use. Text is crisp at arm's length. |
| High | 200 -- 299 | High-end laptops, tablets | Very sharp. Most people cannot distinguish individual pixels. |
| Retina | 300+ | Smartphones, premium tablets | Pixels are invisible to the naked eye. Photo-like quality. |
A note on viewing distance
PPI quality is relative to how far you sit from the screen. A 32-inch 4K monitor at 80 PPI may look perfectly sharp at 3 feet, while a 6-inch phone at the same PPI would look pixelated. Apple's "Retina" threshold accounts for this: ~300 PPI for phones (held at 10-12 inches), ~220 PPI for tablets (15-20 inches), and ~110 PPI for desktops (24-30 inches).
How PPI is Calculated
PPI (pixels per inch) is determined in two steps:
Step 1: Diagonal resolution in pixels
dpixels = sqrt(width2 + height2)
Step 2: Divide by screen diagonal
PPI = dpixels / dinches
Example: 27-inch 4K monitor
- Resolution: 3840 x 2160 pixels
- Diagonal pixels: sqrt(3840^2 + 2160^2) = sqrt(14,745,600 + 4,665,600) = sqrt(19,411,200) = 4,406 px
- PPI = 4,406 / 27 = 163 PPI
- Dot pitch = 25.4 / 163 = 0.156 mm
Other formulas used
- Dot Pitch (mm) = 25.4 / PPI
- Megapixels = (width x height) / 1,000,000
- Aspect Ratio = width:height simplified by their greatest common divisor (GCD)
- Physical width = (width / diagonal pixels) x diagonal inches
- Physical height = (height / diagonal pixels) x diagonal inches
- Display area = physical width x physical height
Aspect Ratio Guide
Aspect ratio describes the proportional relationship between a display's width and height. Here are the most common ratios you will encounter:
| Ratio | Decimal | Common Names | Typical Use |
|---|---|---|---|
| 4:3 | 1.333 | Standard, Classic | Older monitors, iPad, CRT TVs |
| 5:4 | 1.250 | SXGA | Some business monitors |
| 16:9 | 1.778 | Widescreen, HD | Most TVs, monitors, and laptops |
| 16:10 | 1.600 | WUXGA, WQXGA | MacBooks, productivity laptops |
| 21:9 | 2.333 | Ultrawide, Cinemascope | Ultrawide monitors, cinematic content |
| 32:9 | 3.556 | Super ultrawide | Samsung Odyssey-style gaming monitors |
| 3:2 | 1.500 | Surface, PixelSense | Microsoft Surface, Chromebook Pixel |
Frequently Asked Questions
What is PPI (pixels per inch)?
PPI stands for pixels per inch, measuring the pixel density of a display. Higher PPI means more pixels are packed into each inch of screen, resulting in sharper, more detailed images and text. PPI is calculated by dividing the diagonal pixel count by the physical diagonal size in inches.
How do I calculate PPI?
First, find the diagonal resolution in pixels using the Pythagorean theorem: diagonal = sqrt(width^2 + height^2). Then divide by the screen diagonal in inches. For a 1920x1080 display at 24 inches: sqrt(1920^2 + 1080^2) = 2203 pixels, and 2203 / 24 = approximately 92 PPI.
What PPI is considered "Retina" quality?
Apple coined "Retina" to mean a display where individual pixels are indistinguishable at typical viewing distance. For phones held at 10-12 inches, this is around 300+ PPI. For laptops at arm's length, approximately 200+ PPI. For desktop monitors at 2-3 feet, even 110+ PPI can appear pixel-free.
What is the difference between resolution and PPI?
Resolution is the total pixel count (e.g., 3840 x 2160). PPI is pixel density, which depends on both the resolution and the physical screen size. A 4K resolution on a 27-inch monitor yields 163 PPI, but the same resolution on a 55-inch TV gives only 80 PPI. The pixels are the same count but spread over a larger area.
What is dot pitch?
Dot pitch is the physical distance in millimeters between the centers of adjacent pixels. It is the inverse of PPI converted to metric: dot pitch = 25.4 / PPI. A smaller dot pitch means finer detail. A 92 PPI display has a dot pitch of 0.277 mm, while a 300 PPI phone has a dot pitch of only 0.085 mm.
What is aspect ratio?
Aspect ratio is the proportional width-to-height relationship of a display, expressed as two numbers separated by a colon (e.g., 16:9). It is calculated by dividing both the width and height by their greatest common divisor. Most modern displays use 16:9 (widescreen), though 16:10, 21:9, and 3:2 are increasingly common.
Does this calculator store my data?
No. All calculations run entirely in your browser. No data is sent to any server, and nothing is stored.
Privacy & Accuracy
Privacy: This calculator runs entirely in your browser. No data is transmitted or stored.
Accuracy: All values are calculated from standard mathematical formulas. PPI, dot pitch, and physical dimensions are geometrically exact given the inputs. Actual display measurements may vary slightly due to bezels and panel construction. Megapixel counts reflect total addressable pixels, not sub-pixels.
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Screen Resolution Calculator FAQ
What is PPI (pixels per inch)?
PPI stands for pixels per inch. It measures the pixel density of a screen — how many pixels fit into one linear inch. Higher PPI means sharper, more detailed images. PPI is calculated by dividing the diagonal resolution in pixels by the diagonal screen size in inches.
How do I calculate PPI?
To calculate PPI: First find the diagonal resolution using the Pythagorean theorem — diagonal pixels = sqrt(width^2 + height^2). Then divide the diagonal pixels by the screen diagonal size in inches. For example, a 1920x1080 display at 24 inches has a diagonal of 2203 pixels, giving a PPI of about 92.
What PPI is considered 'Retina' quality?
Apple defines Retina as a display where individual pixels are indistinguishable at a normal viewing distance. For phones held at 10-12 inches, this is roughly 300+ PPI. For laptops at arm's length, around 200+ PPI qualifies. For desktop monitors viewed from 2-3 feet, 110+ PPI is often sufficient.
What is the difference between resolution and PPI?
Resolution is the total number of pixels on a screen (e.g., 1920x1080). PPI is the density of those pixels relative to the physical screen size. A 1080p resolution on a 13-inch laptop has much higher PPI (166) than the same resolution on a 27-inch monitor (82). Higher PPI means sharper visuals.
What is dot pitch?
Dot pitch is the physical distance between the centers of two adjacent pixels, measured in millimeters. It is the inverse of PPI (converted to metric). Smaller dot pitch means finer detail. Dot pitch = 25.4 / PPI.
What is aspect ratio?
Aspect ratio is the proportional relationship between a screen's width and height. Common aspect ratios include 16:9 (widescreen), 16:10 (common for laptops), 4:3 (traditional), and 21:9 (ultrawide). It is calculated by dividing both dimensions by their greatest common divisor.
Does this calculator store my data?
No. All calculations run entirely in your browser. No data is sent to any server, and nothing is stored.