PPI calculator
Divide pixel dimensions by the intended print size to find horizontal and vertical pixel density.
Did this calculator give you what you needed?
What could be better?
Two axes expose distortion
Width pixels are divided by width in inches, and height pixels by height in inches. Matching values preserve the source proportions. Different values mean the entered dimensions have different aspect ratios.
PPI is not a universal quality grade
Viewing distance, print process, screening, source detail and the printer’s workflow all affect an acceptable resolution. This tool reports geometry, not a pass/fail recommendation.
The numbers people actually work to
For anything held in the hand, 300 PPI is the conventional target and the figure most print shops quote. Posters viewed from a couple of paces are routinely produced at 150, exhibition banners lower still, and a roadside billboard can be under 20 PPI because nobody stands close enough to see the difference.
That is the pattern worth remembering: the requirement follows viewing distance, not the importance of the job. A 12-megapixel phone photo, 4032 by 3024 pixels, is 13.4 by 10.1 inches at 300 PPI and 26.9 by 20.2 inches at 150. Both are honest answers, and which one you can use depends on where the print will hang.
Frequently asked questions
What PPI do I need for a good print?
Start at 300 PPI for photographs, cards and anything read at arm’s length. Drop to 150 for posters and 100 or less for large-format work seen from several paces. Ask the printer before you resize: a shop that runs a particular press and paper knows what it needs better than any general rule.
What is the difference between PPI and DPI?
PPI counts image pixels per inch, which is a property of your file. DPI counts ink dots per inch, which is a property of the printer, and a machine can lay down several dots to reproduce a single pixel. An inkjet quoting 1440 DPI is not asking for a 1440 PPI image, and the two numbers are not interchangeable.
My width and height PPI came out different. What does that mean?
It means the print size you entered has different proportions from the image, so printing at those dimensions would stretch it. Either correct the target size to match the image ratio, which the aspect ratio calculator will work out, or accept that the image needs cropping to fill the frame.
Is 72 PPI the right resolution for the web?
No, and the number is a leftover from early Macintosh displays. A screen shows an image by its pixel dimensions and ignores the PPI value stored in the file, so a 1200-pixel-wide image looks identical whether it is tagged 72 or 300. PPI only starts to mean something when the image is printed.
Can I just increase the PPI to improve the print?
Not by itself. Changing the number without resampling only changes how large the file says it should print; the pixels are unchanged. Resampling upwards does add pixels, but it invents them from the ones already there, so it can smooth an enlargement without recovering detail that was never captured.