Screen Density Calculator

Calculate DPI/PPI and determine density buckets for mobile devices

Understanding Screen Density

Screen density refers to the number of pixels within a physical area of the screen, typically measured as pixels per inch (PPI) or dots per inch (DPI). Higher density screens display sharper, more detailed images.

Key Concepts

PPI (Pixels Per Inch)

The number of pixels that fit into one inch of the screen. Calculated using the screen resolution and physical size:

PPI = √(width² + height²) / diagonal size

DPI (Dots Per Inch)

Technically different from PPI (used for printers), but the terms are often used interchangeably for screens. For mobile development, PPI is the more accurate term.

Density-Independent Pixels (DP/PT)

A virtual pixel unit that allows you to define UI elements in a way that's independent of screen density:

Android: DP (density-independent pixels)
iOS: PT (points)

Physical Pixels = DP × Density Ratio

Android Density Buckets

Android groups devices into density buckets to simplify resource management:

Bucket	Qualifier	Ratio	PPI Range	Example
ldpi	ldpi	0.75x	~120 PPI	Older devices
mdpi	mdpi	1.0x	~160 PPI	Baseline density
hdpi	hdpi	1.5x	~240 PPI	Budget phones
xhdpi	xhdpi	2.0x	~320 PPI	Most smartphones
xxhdpi	xxhdpi	3.0x	~480 PPI	High-end phones
xxxhdpi	xxxhdpi	4.0x	~640 PPI	Premium devices

iOS Scale Factors

iOS uses a simpler scale factor system:

Scale	Multiplier	Examples
@1x	1x	iPhone 3GS and earlier, iPad 2
@2x	2x	iPhone 4-8, iPhone SE, iPad (3rd gen+)
@3x	3x	iPhone 6 Plus and later Plus/Pro Max models

Providing Graphics Assets

Android

Place drawable resources in density-specific folders:

res/
  drawable-ldpi/
  drawable-mdpi/
  drawable-hdpi/
  drawable-xhdpi/
  drawable-xxhdpi/
  drawable-xxxhdpi/

iOS

Use naming conventions for different scales:

image.png      (1x - 100×100)
image@2x.png   (2x - 200×200)
image@3x.png   (3x - 300×300)

Best Practices

Design at the highest density: Start with xxxhdpi (4x) or @3x and scale down
Use vector graphics: SVG on Android (VectorDrawable), PDF on iOS
Test on multiple devices: Verify appearance across different densities
Optimize file sizes: Use appropriate compression for bitmap images
Use DP/PT for layouts: Never use pixels for sizing UI elements

Common Devices

iPhone

iPhone 14 Pro: 460 PPI (@3x)
iPhone 14: 460 PPI (@3x)
iPhone SE: 326 PPI (@2x)

Android

Pixel 7 Pro: 512 PPI (xxxhdpi)
Galaxy S23: 425 PPI (xxhdpi)
Budget phones: ~220 PPI (hdpi)

Quick Tips

Always design in DP/PT, not pixels
Provide assets for all density buckets
Use 1dp = 1px at mdpi (160 PPI)
Test on physical devices
Consider using vector graphics