Pixel to Inches Converter (DPI Based)
Convert pixel dimensions to inches using DPI (dots per inch).
What the pixel to inches converter does
The pixel to inches converter turns a size in pixels into a physical length, using the resolution in dots per inch (DPI) or pixels per inch (PPI) of the screen or printer. Enter the number of pixels and the DPI, press Calculate, and the tool returns the length in inches. It answers questions such as how large a 1920-pixel image prints at 300 DPI, or how wide a 400-pixel button appears on a particular monitor.
The formula
inches = pixels ÷ DPI
Pixels have no fixed physical size; they only get one when a device decides how many to pack into each inch. The same 1920 pixels are 6.4 inches at 300 DPI, 20 inches at 96 DPI, and 4.2 inches at 460 PPI on a phone.
Worked examples
| Pixels | DPI / PPI | Inches | Centimetres | Context |
|---|---|---|---|---|
| 1920 | 300 | 6.40 | 16.3 | Full-HD frame printed at photo quality |
| 3000 | 300 | 10.00 | 25.4 | Minimum for a 10-inch photo print |
| 1920 | 96 | 20.00 | 50.8 | Same frame at Windows default screen DPI |
| 2560 | 109 | 23.49 | 59.7 | Width of a 27-inch 1440p monitor |
| 1170 | 460 | 2.54 | 6.5 | Width of a 6.1-inch phone display |
| 600 | 72 | 8.33 | 21.2 | Legacy 72 DPI assumption in old design software |
Finding the DPI of a device
- Screens. PPI = √(horizontal² + vertical²) ÷ diagonal in inches. A 27-inch 2560 × 1440 monitor has √(2560² + 1440²) = 2937 pixels on the diagonal, so 2937 ÷ 27 = 109 PPI. The screen PPD calculator extends this to viewing distance.
- Printers. The print DPI is whatever you set when exporting; 300 is the standard for photographs and brochures, 150 for large posters viewed from a distance, 600 or more for fine text.
- Operating systems. Windows assumes 96 DPI at 100% scaling, macOS assumes 72 points per inch with 2× pixel density on Retina displays. CSS defines a reference pixel at 96 per inch regardless of the actual screen.
Print sizes from image dimensions
| Image (pixels) | Largest print at 300 DPI | Acceptable at 150 DPI |
|---|---|---|
| 1200 × 1800 | 4 × 6 in | 8 × 12 in |
| 2400 × 3000 | 8 × 10 in | 16 × 20 in |
| 3000 × 4500 | 10 × 15 in | 20 × 30 in |
| 4000 × 6000 (24 MP camera) | 13.3 × 20 in | 26.7 × 40 in |
| 6000 × 8000 (48 MP camera) | 20 × 26.7 in | 40 × 53 in |
DPI versus PPI
PPI describes pixels on a screen or in an image file; DPI describes ink dots a printer lays down. Printers use many dots to render one image pixel, so a 1440 DPI inkjet still only needs 300 PPI of image data. The two terms are used interchangeably in software, and the converter treats them the same: enter the pixels-per-inch figure that applies to your output.
Common mistakes
- Trusting the DPI stored in an image file. It is metadata that any program can change; it does not alter the pixels. Only the pixel count and the DPI you print at determine size.
- Upscaling to reach 300 DPI. Adding pixels in software does not add detail. Print smaller or accept a lower DPI.
- Using 72 DPI for the web. Modern screens range from 96 to over 500 PPI; the 72 figure is a relic of early Macintosh displays.
- Mixing up width and diagonal. Screen PPI is calculated from the diagonal; the converter then works on width or height separately.
Related tools
The screen size converter gives width and height from a diagonal and aspect ratio, and the length calculator converts inches to centimetres or millimetres. The inches to fraction calculator turns 6.40 inches into 6 ⅜ for a tape measure, and the area converter handles print area in square units.
External references
Frequently asked questions
How many pixels are in an inch?
As many as the device puts there: 96 on a typical desktop monitor, 220 on a high-resolution laptop, 300 in a photo print, 460 on a flagship phone.
What DPI do I need for a good print?
300 for prints viewed close up, 150 to 200 for posters, and as low as 50 for billboards seen from across a street.
How do I convert inches back to pixels?
Multiply by the DPI. A 5 × 7 inch print at 300 DPI needs 1500 × 2100 pixels.
Does changing DPI in Photoshop change my image?
Only if “resample” is ticked. With resampling off, it changes the intended print size and leaves the pixels untouched.
Why does a 1920-pixel image look different in size on two monitors?
The monitors have different pixel densities. At 100% zoom each shows the same pixels, so the one with more pixels per inch shows it smaller.