How Many Pixels Are in an Inch: px and in Explained with PPI/DPI

There’s no single fixed number of pixels in an inch. The conversion depends entirely on PPI/DPI.

If you search “how many pixels in an inch”, you’ll quickly notice something confusing: there isn’t one universal number. Pixels don’t have a physical size by themselves—they only become “inches” (a real-world measurement) once you define a pixels-per-inch value.

This article explains the relationship between pixels and inches, gives the exact formulas, and shows practical examples across common fields. If you want instant conversions, jump to our tools:

Pixels vs Inches: What’s the Relationship?

Inch (in) is a physical unit of length. It’s fixed: 1 inch = 2.54 cm.
Pixel (px) is a digital unit—one dot in an image or on a display. A pixel does not equal a fixed physical size.

To connect them, you need a density value:

PPI (Pixels Per Inch): how many pixels fit into one inch on a display or in a digital-to-physical mapping.
DPI (Dots Per Inch): commonly used in printing/scanning contexts. For size conversion, people often use DPI similarly to PPI (even though “dot” and “pixel” aren’t the same concept).

So the real answer to “how many pixels in an inch” is:

At a given PPI, 1 inch contains exactly that many pixels.
Example: at 300 PPI, 1 inch = 300 px.

The Conversion Formulas

Convert inches to pixels

pixels = inches × PPI

Convert pixels to inches

inches = pixels ÷ PPI

Common PPI/DPI Tables

Different industries use different “typical” PPI/DPI targets. Here are common reference points:

Use Case	PPI/DPI	Pixel	Notes
Web / CSS (logical pixels)	96 PPI	96 px	A traditional baseline for CSS px; not the same as physical screen density
Office printing (documents)	150–200 DPI	150–200 px	Usually fine for text, moderate detail
High-quality print (posters/books)	300 DPI	300 px	The most common “print-quality” standard
Photo printing	240–300 PPI	240–300 px	Depends on printer and viewing distance
Smartphone displays (“retina”-class)	~326 PPI	326 px	Typical density tier for many phones
Very high-density displays	450+ PPI	450+ px	Extremely sharp, but heavier on rendering/assets

Key takeaway:

For printing, you usually choose a DPI target (often 300).
For screens and UI, physical inches matter less than logical layout units (CSS px, device scaling). PPI is still useful when you need real-world sizing.

Quick Practical Calculations

Example 1: Print — 2 inches wide at 300 DPI

pixels = 2 × 300 = 600 px

Example 2: Screen — 1200 px wide at 96 PPI

inches = 1200 ÷ 96 = 12.5 in

Example 3: Photo print — 4×6 inches at 300 PPI

Width: 4 × 300 = 1200 px 
Height: 6 × 300 = 1800 px

Which PPI/DPI Should You Use?

Use this as a simple rule of thumb:

Web/UI work: Start from design pixels and layout rules (CSS px, responsive design). Physical inches are rarely the target.
Everyday printing: 150–200 DPI is often fine for text-heavy documents.
High-quality printing: 300 DPI is the safest default for sharp results.
Photos: 240–300 PPI is a common range depending on expectations and viewing distance.

Summary

There’s no single fixed number of pixels in an inch. The conversion depends entirely on PPI/DPI:

1 inch = PPI pixels
pixels = inches × PPI
inches = pixels ÷ PPI