DPI Calculator
Calculate DPI, pixel requirements, or print size for any image. Work in pixels, inches, or resolution and solve the third value. Free and instant.
Print DPI is not a quality setting you apply to a file. It is a number that falls out of two other numbers: the pixels you have and the physical size you want. This calculator solves for whichever of the three you do not have, so you can go from a photo size to a resolution, or from a resolution to the pixels a print shop will ask for.
How it works
The three numbers and how they relate
Pixels, physical size, and resolution are three views of the same fact. Any two of them give you the third, which is why this calculator asks what you are looking for. Choose the value you want, enter the two you have, and the answer is the third.
DPI = pixels / inches pixels = inches × DPI inches = pixels / DPI
What resolution each kind of output needs
Resolution is chosen to match how the image is seen, not because one number is better than another. A print held in the hand needs the pixels dense enough that the gaps are invisible up close. A poster across a room does not, and choosing 300 PPI for one only makes the file huge and the print smaller than it could be.
| Output | Recommended DPI | Why |
|---|---|---|
| Photo prints, A4 pages | 300 DPI | Viewed at arm length, so gaps must be invisible |
| Large posters and banners | 150 to 200 PPI | Viewed from a distance, so lower density still looks sharp |
| Photo books | 300 DPI | Pages are read closely and often reprinted |
| Screen and email images | 72 to 96 PPI | Display density replaces any print measurement |
| Scans for archiving | 300 DPI | Preserves small text for later reading |
| Embroidery and some craft vinyl | 300 PPI | Thread or blade width is larger than a print dot |
A worked example in both directions
The same relationship reads well in either direction. Start with what a print shop asks for: a 5 by 7 inch photo at 300 DPI needs 1,500 by 2,100 pixels. Now run it backwards with a file you already have. A 4,000 by 3,000 pixel photo at 300 DPI prints 13.33 by 10 inches, so a print shop asking for 5 by 7 will not be able to use the full width without cropping.
- Pixels you have and print size you want give you the resolution you will actually achieve.
- Resolution target and print size give you the pixel requirement, which is what you ask a designer for.
- Use the pixels to inches converter for the same maths in metric, or the print size calculator for the largest size a file supports.
DPI in a file is a label, not a quality setting
Editing the DPI value inside a file changes nothing about the image. The pixel count is the pixel count, and the file size is the file size. What changes is the size a program assumes the image should print at, so the same file printed at its stored DPI and at a different one will be different physical sizes with different apparent sharpness. That is why a low DPI image is not a low quality image. It may be a perfectly detailed image labelled for a small print.
NoteEnlarging an image raises neither its pixels nor its detail. If a print shop needs more resolution than you have, the fix is a larger source image, not a different number in the file.
Frequently asked questions
What is a good DPI for printing?
300 DPI for photographs and artwork viewed at close range. Between 150 and 200 DPI is enough for posters seen from a distance, because the eye cannot resolve the difference. Below about 100 DPI, prints start to look visibly soft.
How do I find the DPI of an image?
Divide the pixel dimension by the physical size in inches. A 3,000 by 2,000 image printed 10 inches wide is 300 DPI, because 3,000 divided by 10 is 300.
Does DPI affect file size?
Not by itself. File size comes from pixel count and compression, and DPI is only a number stored in the file that describes intended print size. You can change it without changing the bytes. To reduce file size, compress instead.
Is DPI the same as PPI?
Strictly, DPI counts printed dots and PPI counts pixels. In practice they are used interchangeably, and for this calculation they behave identically, because both are the number of units packed into one inch. Many tools label the field either way.
Can I increase DPI without losing quality?
No. Writing a higher DPI value into a file changes only the number a program reads, not the underlying pixels. The print will come out the same physical size but softer. To get more detail, you need an image with more pixels in the first place.