What does DPI stand for? It stands for dots per inch, a count of how many tiny dots of ink or toner a printer places along one inch of paper. The higher the number, the finer the detail a printed photo or page can show.
You also see DPI on computer mouse settings and in image editing software, where people often use it loosely for pixels per inch. The idea is always the same: how much detail is packed into each inch.
Quick facts
Stands for
Dots per inchType
Initialism, said D P IUsed in
Printers, scanners, image files, gaming miceCommon values
300 for photo prints, 150 for drafts, 600 or more for scans of fine textClose cousin
PPI, pixels per inchOther meanings
Deep packet inspection; Department of Public Instruction
DPI stands for dots per inch: what that measures
Picture a line one inch long on a printed page. If the printer can lay down 300 separate dots along that line, it is printing at 300 DPI. More dots in the same space means smaller dots, smoother curves and cleaner small type.
| Job | Usual DPI | Why |
|---|---|---|
| Draft documents | 150 to 300 | Readable text, saves ink |
| Photo prints | 300 | Detail looks sharp at normal viewing distance |
| Scanning old photos | 600 or higher | Lets you enlarge them later |
| Large posters | Often lower | People view them from farther away |
What does DPI stand for on a mouse?
On a computer mouse, the number tells you how far the pointer moves on screen for each inch you slide the mouse. A low setting such as 800 moves the pointer slowly and precisely. A high setting such as 3,200 sends it across the screen with a small flick of the wrist.
Engineers sometimes call this CPI, counts per inch, because the sensor counts movements rather than printing dots. Box labels and settings menus usually still say DPI. Gamers often lower it for careful aim and raise it for fast menus.
In a mouse settings app: "DPI stages: 400, 800, 1600." Pressing the button under the scroll wheel cycles through those three speeds.
DPI vs PPI
Print shops and photographers confuse these constantly, and in casual talk people often treat them as the same.
- DPI, dots per inch: a property of a printer or a printed page. Ink dots on paper.
- PPI, pixels per inch: a property of a digital image or a screen. Square pixels in a grid.
When a print shop asks for "a 300 DPI file," it really means an image with enough pixels to print at 300 pixels per inch at the final size. A quick way to check: multiply the print size by 300. A 4 by 6 inch photo needs about 1,200 by 1,800 pixels. For more on image files, see PNG and PDF.
Other things DPI can mean
Context usually makes the right meaning clear.
- Deep packet inspection: in networking, a way for a firewall or provider to look inside data packets, not just at their addresses. You may see it next to terms like VPN and ISP.
- Department of Public Instruction: the name of the state education agency in a few states, such as Wisconsin and North Carolina.
- Disposable personal income: an economics term for income left after taxes.
If the topic is ink, paper, scans or a mouse, it is dots per inch. For more screen and print letters, visit the tech acronyms hub.
Writing DPI correctly
Say the letters one by one: D P I. Write it in capitals, with a space before it after a number: 300 DPI. Some style guides prefer lowercase dpi, and both are understood. There is no plural form; you write 600 DPI, not 600 DPIs.
- "Scan the receipts at 300 DPI."
- "My mouse is set to 1,600 DPI."
- "The logo file is too low DPI to print on a banner."
- "Export the flyer as a high DPI image."
Questions people ask
Is higher DPI always better?
Not always. Past a certain point, the eye cannot see the extra detail, and the file just gets bigger. For most home photo prints, 300 is plenty.
What does 72 DPI mean?
It is an old rule of thumb for images meant only for screens. It does not control how sharp an image looks on a monitor, since screens show images by pixel count.
What DPI should I scan documents at?
For plain text documents, 300 DPI is a common choice. Use 600 or more for small print, old photos or anything you may want to enlarge.
How do you pronounce DPI?
Say each letter: D P I. Nobody says it as a word.