Pixel Density Calculator
Calculate PPI (pixels per inch) and DPI from screen resolution and physical size.
About this tool
Pixel Density Calculator helps you understand the sharpness and clarity of digital displays by calculating PPI (pixels per inch) and DPI (dots per inch) from screen resolution and physical size. PPI and DPI are critical metrics for evaluating display quality across devices ranging from smartphones and tablets to monitors, televisions, and projectors. A higher pixel density means more pixels are packed into each inch of the display, resulting in sharper text, crisper images, and a more immersive visual experience.
To use the calculator, enter your screen's resolution (horizontal and vertical pixel dimensions) and the physical screen size (typically in inches or centimeters). The tool instantly computes the pixel density in PPI or DPI, helping you determine whether your display is sharp enough for your needs. This is especially valuable when comparing devices before purchase, understanding why one phone appears crisper than another despite similar screen sizes, or evaluating whether a monitor is suitable for detailed design work, image editing, or general productivity.
Display professionals, designers, photographers, and developers rely on this calculator to match pixel density with intended use cases. For example, displays above 300 PPI are considered retina-quality and suitable for close viewing (like smartphones), while monitors for desktop work typically range from 90 to 150 PPI. Understanding pixel density helps you make informed decisions about device selection and ensures optimal visual comfort during extended screen time.
Frequently Asked Questions
Code Implementation
import math
def calculate_ppi(width_px: int, height_px: int, diagonal_inches: float) -> float:
"""Calculate PPI from screen resolution and diagonal size."""
diagonal_px = math.sqrt(width_px**2 + height_px**2)
return diagonal_px / diagonal_inches
def ppi_to_dpcm(ppi: float) -> float:
"""Convert PPI to dots per centimeter."""
return ppi / 2.54
def dpcm_to_ppi(dpcm: float) -> float:
"""Convert dots per centimeter to PPI."""
return dpcm * 2.54
# Common screen PPI calculations
screens = [
("iPhone 15 Pro", 2556, 1179, 6.1),
("MacBook Pro 14", 3024, 1964, 14.2),
('4K 27" Monitor', 3840, 2160, 27.0),
('FHD 27" Monitor', 1920, 1080, 27.0),
('4K 55" TV', 3840, 2160, 55.0),
]
print(f"{'Screen':<22} {'Resolution':<15} {'Diagonal':>8} {'PPI':>7} Category")
print("-" * 70)
for name, w, h, d in screens:
ppi = calculate_ppi(w, h, d)
category = "Retina (≥220)" if ppi >= 220 else "High-DPI (≥150)" if ppi >= 150 else "Standard"
print(f"{name:<22} {w}×{h:<9} {d:>6.1f}" {ppi:>6.1f} {category}")
# Output:
# iPhone 15 Pro 2556×1179 6.1" 460.4 Retina (≥220)
# MacBook Pro 14 3024×1964 14.2" 253.6 Retina (≥220)
# 4K 27" Monitor 3840×2160 27.0" 163.2 High-DPI (≥150)
# FHD 27" Monitor 1920×1080 27.0" 81.6 Standard
# 4K 55" TV 3840×2160 55.0" 80.1 StandardComments & Feedback
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