Even though "dots per inch" (dpi) and "pixels per inch" (ppi) are used
interchangeably by many, they are not the same thing. Traditional printing
methods use patterns of dots to render photographic images on a printed
page. While pixels on a monitor are square and in contact with
the adjacent pixels, printed dots have space between them to make
white, or no space between them to make black. Color photographs are printed
using four inks, Cyan, Magenta, Yellow, and Black (CMYK), and four separate
dot patterns, one for each ink. Dots per inch (dpi) refers to printed dots
and the space between them, while pixels per inch (ppi) refers to the square
pixels in a digital image. Keep in mind that many companies will ask for
images at 300dpi when they really mean 300ppi.
First, some background information is necessary. A digital image is what it
is. It is however many pixels wide by however
many pixels tall. If you divide each dimension by 300, you will have the
size of the image at 300ppi. Now think about 300 pixels in an inch of space.
Each pixel could be black, white, or any other color, but they are
all next to each other with no spaces between them. When a digital image
is prepared for reproduction on a printing press, pixels are converted to
dots. Dots have spaces between them. 300 pixels become
150 dots and spaces, so 300ppi becomes roughly 150dpi. 150dpi is the accepted
standard for printing photographic quality images.
Printers usually refer to the number of rows or lines per inch (LPI). 150 lines per inch is simply 150 rows of 150 dots per inch. 150 LPI and 133 LPI have long been the established standards for the best quality reproduction of photographs in books and magazines. Newspapers traditionally use 85 LPI for photographs and detail is lost because the dots are plainly visible.
Everything is relative to viewing distance. 150dpi (or 300ppi) is accepted as
photo quality because the average person cannot see the "dots" at a few inches
away. A real photograph made from film in a darkroom has no dots or pixels and
therefore is the standard by which "photo quality" is judged. When you move the
viewer further away from the printed material, lower dpi is acceptable. A huge billboard
might be printed at only 40dpi but no one notices because everyone is 50 yards
away from it.
72dpi should really be 72ppi because most likely, it has nothing to do with
printing. Most of the time, 72dpi refers to output on a computer
monitor. A 72 pixel by 72 pixel image should take up about one inch
of space on the screen. This of course depends on the size of the monitor
and what resolution it is set to. When creating images for web
sites, we've found it's best to determine what screen resolutions will
be used most often by that site's visitors, instead of thinking about
inches at all.
|Megapixels||Pixel Resolution*||Print Size @ 300ppi||Print size @ 200ppi||Print size @ 150ppi**|
|2048 x 1536||6.82" x 5.12"||10.24" x 7.68"||13.65" x 10.24"|
|2464 x 1632||8.21" x 5.44"||12.32" x 8.16"||16.42" x 10.88"|
|3008 x 2000||10.02" x 6.67"||15.04" x 10.00"||20.05" x 13.34"|
|3264 x 2448||10.88" x 8.16"||16.32" x 12.24"||21.76" x 16.32"|
|3872 x 2592||12.91" x 8.64"||19.36" x 12.96"||25.81" x 17.28"|
|4290 x 2800||14.30" x 9.34"||21.45" x 14.00"||28.60" x 18.67"|
|4920 x 3264||16.40" x 10.88"||24.60" x 16.32"||32.80" x 21.76"|
|35mm film, scanned||5380 x 3620||17.93" x 12.06"||26.90" x 18.10"||35.87" x 24.13"|
*Typical Resolution. Actual pixel dimensions vary from camera to camera.
**At 150ppi, printed images will have visible pixels and details will look "fuzzy".
For a chart of megapixels vs. maximum print size at 300ppi,
see our Megapixels Chart.
21 Jun 2012 8:51pm
"Very Helpful, easy to follow, thank you"
11 Oct 2011 3:33am
"Great job with this info. I'm a print designer and have always been told that 300 dpi is the "offset" printing standard not 150 dpi as you have stated above: "Why do I need 300ppi for a "photo quality" image?. 150dpi is the accepted standard for printing photographic quality images." You may be referring to photography output."
24 Jul 2011 8:21am
"If I shoot 1,000 pictures a month at around 5184 x 3456, they take up 5 -6 megs. Is this overkill for photos that will rarely be printed larger than 8 x 10? 99.99% will only be printed at 4 x 6 or a few at 5 x 7..... but I worry that I will take that all time great picture and not be able to print a large copy. At what resolution would you recommend shooting photos and why? Thanks for a great article."
23 Jun 2011 9:57am
"Thank you very much. I've just bought a simple nikon coolpix for holiday rather than carry the DSLR and was wondering what resolution to set it on for default (as I expect I'll use the images on facebook and some 6x4 photos from partial crops). I found your site with the first google phrase and can only echo the other earlier comments. Your table was just what I was looking for - the clear explanation an added bonus."
21 Feb 2011 2:27pm
"My canon SLR shoots at 72 ppi(and can't be changed). It is a 12 meg photo. Should I be upsizing in photoshop to print a better quality photo? I thought it was not a very good thing to do - upsize. I thought this was a good camera, now I am not so sure. Can you help explain this?
[Reply from Robert Giordano]
The default setting of 72 ppi means very little and you can change it to whatever you want WITHOUT "upsizing". In Photoshop, simply go to Image > Image Size... and UNCHECK the "Resample Image" box. Then, you can change "Resolution" from 72 to 150 or 300 ppi. The pixel dimensions at the top should stay the same. You are simply changing how many pixels will be printed per inch of paper."
16 Feb 2011 6:26pm
"It was very useful in understanding the concept. Thanks"
15 Feb 2011 10:47pm
"We wanted to actually see how different dpi's printed which is why we produced this handbook. It has examples of a photo printed at: 600dpi, 300dpi, 200dpi, 100dpi, 72dpi & 50dpi. Do check it out if you think it would be useful: www.printhandbook.com
[Reply from Robert Giordano]
Nice work. I made one of those a couple of years ago, just to show to clients. Cheers!"
27 Oct 2010 4:43am
"Nice job! I think what you've written about will become important again with panoramas and high def image stitching."
29 Mar 2010 2:56am
"Very informative site, just a little additional info. The center of the printed dots are a constant distant from each other (frequency), they will vary in size depending on the amount of ink required and over 50% will overlap each other. ppi is a digital resolution, lpi is the screen ruling used by printers to create the tonal variation in a colour image, dpi is the output resolution used by an imagesetter or CTP system."
22 Dec 2009 10:08am
"excellent, clear, simple way of understanding ppi dpi, im only just learning but you explain it so easy to understand thank you"
13 Dec 2009 11:59am
"Very clear explanation of a topic that should be better known, but is definitely nothing more than a series of vague concepts in many peoples minds. Outstanding descriptions that anyone with an interest can understand. Thanks!"
21 Oct 2009 4:22am
"This is the information I was looking for. I was just having a discussion with our web designer that ppi and dpi are not the same. I have a print background so I understand four color process, my co-worker is strictly web and claimed dpi and ppi are the same thing. Thanks for explaining this so clearly."
22 Jul 2009 7:11pm
"One of the few sites around with an accurate and clear description. Every site should just link to this instead. Good work."
12 Jun 2009 9:53am
"I've tryed to explain these concepts to clients and would be digital camera owners for years. Their eyes simply glaze over (ppi, dpi, 72 ppi native resolution, 300 dpi reproduction resolution . . . oops there they go!). In future I'll just send them here. Very well presented. A goldmine for the digital age. One tip, Postscript rasterizes 305.9 dpi faster and better than 300."
31 May 2009 6:59am
"An honourable man remained true and loyal to his wife Lorraine, although his true love was Clearly. Lorraine finally passed away and shortly after Lorraine's funeral he sang this song. "I CAN SEE CLEARLY NOW, LORRAINE IS GONE". Thank you! I can see clearly now also. The best explanation yet. Dick Kane"
15 Apr 2009 1:11am
"this is such a tricky info shared in such a simple way i love the way you explain literally thank you indeed"
01 Apr 2009 2:56pm
"Awesome job at explaining the difference between everything! Been doing photography for 15 yrs and the last 10 of those digital. Never found anything that explained very clearly everything as you did here. I very much appreciate it! Thanks again ~Jen Martinez"
08 Mar 2009 11:21am
"Just want to say thank you, your post gives me all the info that I'm searching for."
06 Jan 2009 9:52am
"Well done. It took ages to find a website the explained all about dpi and ppi in simple terms. Your charts are brilliant. Pity the camera people don't tell the truth about print sizes. Thank You."
06 Nov 2008 4:15pm
"what does this mean: Images should be 1024 pixels on the longest side at 72DPI. This is a submission guide line for a digital photo contest Thanks!
[Reply from Robert Giordano]
That's actually kind of ridiculous because they're giving you pixel dimensions. 1024 pixels is 1024 pixels at ANY DPI!"
14 Sep 2008 11:46am
"This is what I have been searching for, lucky for me I was given the link in a forum... great explanation! (I can see clearly now the rain has gone...) thank you"
10 Aug 2008 10:29pm
"Simple just as i like thank you great just what i needed"
12 Jul 2008 6:05pm
"Thank you, thank you, thank you! This is what I have been looking for, clear concise understandable information."
05 Jun 2008 8:37am
"Excellent, this is exactly what I was looking for."
02 Jun 2008 8:57am
"great information, thanks for taking the time to table the usefull information. :)"
01 Jun 2008 7:09pm
"Thank you so much for reminding me of these very crucial points!"
21 May 2008 11:30am
"I have read many explanations from various photo forums and other technical (professional) sites on this topic, DPI vs PPI and printing size. I am no longer unsure of what those terms mean and why they are used (and misused). Thanks, Peter Ellis"
24 Apr 2008 4:25am
"extremely useful. Googled a lot of words till I came up with this page. Pretty much what I was looking for- dpi, ppi, megapixels and size of prints."
08 Mar 2008 9:33am
"people still use the term dpi over ppi so much. even the most respected web sites."
17 Feb 2008 9:40am
"Thank you for trying to dispel some of the many myths when it comes to photography and printing. A couple of nits about the article. All color monitors that I am aware of (CRTs and LCDs) actually have black spaces between the imaging areas. They are small, but they are there. Secondly, I believe that the 72 DPI has a lot to do with printing. A typesetting Point is about 1/72 inch. There are 12 Points to a Pica."
10 Nov 2007 7:43am
"I worked as a lithographer for over ten years. I have a very clear understanding of what DPI is. You did a great job in describing the difference between DPI and PPI. Do you think you could go a step futher and explain that overlapping the CYMK dots results in seeing all the colors of an image (picture)."
08 Jun 2007 4:36pm
"I've read your charts and the information given in these topics are just wonderful. It's added a big amount of information in my photography data back in my mind. I didn't have so much idea about the pixel or ppi and dpi stuff but it's really gonna help me a lot in future. Now I can really think of buying a proper SLR or other digital cam which would suit my requirements. Please add some detailed know how of SLR's, like what they are or how they different from other cams. Thanks Vikas Verma"