Print & screen

DPI Converter

Q: What DPI should I use for printing?

Use 300 DPI for photos and detailed print, and 150 DPI for drafts or large items viewed from a distance. Screens generally assume 96 DPI.

Turn a pixel dimension into a physical size at a given resolution (dots per inch).

How to convert pixels to inches with DPI

DPI (dots per inch) tells you how many pixels fit into one inch of physical space. To convert a pixel dimension into a real-world size, divide the number of pixels by the DPI:

Inches = pixels ÷ DPI
Centimeters = inches × 2.54
Millimeters = inches × 25.4

For example, an image 1920 px wide at 96 DPI is 1920 ÷ 96 = 20 inches (50.8 cm) on screen. Send that same file to a 300 DPI photo printer and it becomes just 6.4 inches wide — same pixels, a higher resolution, a smaller print. Type any pixel count and DPI above and all three sizes update instantly.

Common DPI values

The right DPI depends on whether your work is shown on a screen or printed on paper. These are the resolutions you will meet most often:

DPI	Typical use	1000 px equals
72	Legacy web / older Mac displays	13.889"
96	Standard screen resolution	10.417"
150	Draft / office printing	6.667"
300	Photo and magazine print	3.333"

DPI, PPI and print quality

On screens the figure is technically PPI (pixels per inch), while DPI describes the ink dots a printer lays down, but the two terms are used interchangeably for sizing. The key point is that a higher DPI packs the same pixels into a smaller area, producing sharper print. For crisp photo output aim for 300 DPI; for large banners viewed from a distance, 150 DPI or even less is plenty.

Choosing a resolution by viewing distance

The familiar "always use 300 DPI" advice is really a rule of thumb derived from how far away the thing will be. The eye resolves roughly 300 PPI at about 12 inches; double the distance and you can halve the resolution with no visible difference. That gives a far more useful guide than one number:

Output	Viewed from	Resolution
Photo book, magazine, business card	~12 in	300 DPI
Poster on a wall	3–6 ft	150 DPI
Exhibition banner	10 ft+	100 DPI
Billboard	50 ft+	20–30 DPI

This is why billboards are printed from files that would look dreadful on a desk. Preparing a large-format job at 300 DPI produces an enormous file for detail no viewer will ever resolve.

Working out the largest size a file can print

Run the conversion backwards: divide each pixel dimension by your target resolution. A 3000 × 2000 photo prints 10 × 6.7 inches at 300 DPI, or 20 × 13.3 inches at 150. A 12-megapixel phone photo (about 4000 × 3000) is comfortable at A4 and perfectly acceptable as an A3 poster. A 1920 × 1080 screenshot is a 6-inch print at best — which is why screenshots so often disappoint in printed documents.

Note that raising the DPI setting in an export dialog without changing the pixel count does not add detail. It simply prints the same image smaller. Detail has to be captured; it cannot be created afterwards.

Scanning at the right resolution

Scanning runs the same arithmetic in reverse: the DPI you scan at decides how large the result can be reproduced. Scan a 6 × 4-inch photo at 300 DPI and you get 1800 × 1200 pixels — enough to reprint at the same size, but not to enlarge.

So scan for the output you want, not the original. To reprint that photo at 12 × 8 inches you need 600 DPI; for archival copies of small originals, or for 35 mm negatives, 1200–2400 DPI is normal. Beyond about 2400 DPI most flatbed scanners are interpolating rather than genuinely resolving more, so the file grows without the detail improving.

Frequently asked questions

How do I convert pixels to inches?

Divide the pixel dimension by the DPI: inches = pixels ÷ DPI. For example 600 px at 300 DPI is 2 inches. Enter the values above and the converter also shows centimeters and millimeters.

What is the difference between DPI and PPI?

PPI (pixels per inch) describes pixels on a screen, while DPI (dots per inch) describes ink dots from a printer. For converting an image size they are treated as the same number.

What DPI should I use for printing?

Use 300 DPI for photos and detailed print, and 150 DPI for drafts or large items viewed from a distance. Screens generally assume 96 DPI.

Does a higher DPI make my image bigger?

No — for a fixed pixel count, a higher DPI makes the physical size smaller because the same pixels are packed more tightly, which increases sharpness.

What's the largest size I can print my photo?

Divide each pixel dimension by your target DPI. A 3000 × 2000 photo is 10 × 6.7 inches at 300 DPI, or double that at 150 DPI for a poster viewed from a few feet away.

What DPI should I scan at?

Scan for the output size you want, not the original. 300 DPI reproduces at the same size; 600 DPI lets you double it. Past about 2400 DPI most flatbeds interpolate rather than resolve genuine extra detail.