Calculate display dimensions, PPI, aspect ratio, and viewable area from diagonal size and resolution. Compare monitors, TVs, tablets, and phones.
The Screen Size Calculator converts a display's diagonal measurement and resolution into exact width, height, area, PPI (pixels per inch), and pixel density metrics. Enter any screen's diagonal and resolution to see its precise physical dimensions and how it compares to other displays.
Manufacturers advertise screen size as the diagonal measurement, but two 27-inch monitors can feel very different depending on their aspect ratio. A 27" 16:9 display is 23.5" wide and 13.2" tall, while a 27" 21:9 ultrawide is 25.1" wide but only 10.7" tall — nearly 20% less vertical space.
This calculator reveals the hidden dimensions, computes pixels per inch to gauge sharpness, and compares multiple displays side by side. It also calculates optimal viewing distance based on visual acuity and resolution, helping you decide between a 27" 1440p and a 32" 4K monitor. Check the example with realistic values before reporting. Use the steps shown to verify rounding and units. Cross-check this output using a known reference case.
Understand exact physical dimensions, sharpness, and optimal viewing distance for any display. Essential for choosing between monitors, TVs, and mobile devices. Keep these notes focused on your current workflow. Tie the context to real calculations your team runs. Use this clarification to avoid ambiguous interpretation. Align the note with how outputs are reviewed. Apply this only where interpretation varies by use case.
Width = Diagonal × cos(atan(V_res / H_res)). Height = Diagonal × sin(atan(V_res / H_res)). PPI = √(H_res² + V_res²) / Diagonal. Area = Width × Height.
Result: 23.53" × 13.24", 108.79 PPI, 311.5 sq in
A 27" 16:9 display at 2560×1440 has PPI of 108.79. The physical width is 23.53 inches and height is 13.24 inches, with a total viewable area of 311.5 square inches.
PPI (Pixels Per Inch) measures how tightly pixels are packed. Higher PPI means sharper text, smoother curves, and less visible pixel grid. The PPI formula uses the Pythagorean theorem on the resolution to find the diagonal pixel count, then divides by the physical diagonal.
At 96 PPI (a "standard" Windows DPI), pixels are about 0.265mm wide — easily visible from arm's length. At 220 PPI (MacBook Retina), pixels are 0.115mm — invisible to most eyes at laptop distance. At 460 PPI (modern phones), individual pixels require a magnifying glass to see.
The 16:9 (1.78:1) ratio dominates consumer displays because it balances widescreen media consumption with productivity. For ultrawide productivity, 21:9 (2.33:1) provides ~33% more horizontal space. For cinema buffs, 32:9 (3.56:1) displays approximate two 16:9 screens edge-to-edge.
Vertical monitors (rotated 16:9) provide excellent code/document viewing at 9:16 — 1440×2560 offers tremendous vertical scroll space for reading and development work.
The human eye can resolve about 1 arcminute of detail. This means pixel size (in arcminutes at viewing distance) determines whether resolution matters. At 3 feet from a 27" 1080p (82 PPI), each pixel subtends ~1.6 arcminutes — clearly resolvable. At 10 feet from a 65" 4K TV (68 PPI), each pixel subtends ~0.5 arcminutes — invisible. This is why huge 4K TVs look sharp across the room but small 1080p monitors look grainy up close.
Apple defines Retina as PPI where individual pixels are not discernible at typical viewing distance. For laptops (~18"), that's ~220+ PPI. For desktop monitors (~24"), ~110+ PPI. For phones (~12"), ~300+ PPI.
At ~82 PPI, individual pixels are visible from typical desk distance (2-3 feet). 27" 1440p (~109 PPI) is a significant sharpness upgrade. 27" 4K (~163 PPI) is visually flawless for most users.
For 4K: 1-1.5× the diagonal. For 1080p: 2-3× the diagonal. A 65" 4K TV is ideal at 5.5-8 feet. Sitting closer reveals more detail from 4K resolution; sitting farther makes 1080p acceptable.
16:9 is the standard widescreen ratio (1920×1080, 2560×1440, 3840×2160). 21:9 ultra-widescreen (2560×1080, 3440×1440) is 33% wider but has the same height as a smaller 16:9 — offering more horizontal workspace.
Beyond a certain distance-dependent threshold, higher PPI provides no visible benefit. For desktop monitors at 24", diminishing returns begin around 120 PPI. But for VR headsets and close-viewing devices, 500+ PPI is desirable.
Use PPI for sharpness and total area (sq in) for content space. A 32" 1440p (91 PPI) is larger but less sharp than a 24" 1440p (122 PPI). Consider your use case: photo editing favors PPI; multitasking favors area.