I often see statements in discussions about web displayed image quality that go something like this: "I only upload pictures at 72 dpi and 1200 pixels on the long edge, so if someone copies and prints the image it won't look as good as if it were 300 dpi."

What? Have I missed something here?

Does an image edited and saved/exported with 1200x800 pixels at 300 ppi look any different online than the same image saved/exported with 1200x800 pixels at 72 ppi? Other than the metadata regarding ppi, is there any difference in the two images at all? If so, what is the difference? If I tell my printer to print the images at 4R (4X6 inches) will there be any difference at all in how the printer creates a print from the 1200x800 @ 300 dpi image versus the 1200x800 @ 72 dpi image?


8 Answers 8


You ask if there is a practical difference. So the answer is yes, albeit a very small one, but some of the other answers have missed it.

You're right that the only difference is in the metadata: if you save the same image as 300dpi and 72dpi the pixels are exactly the same, only the EXIF data embedded in the image file is different. (I've even verified this using a Beyond Compare, a file comparison tool.) If you open the two images on screen you will see absolutely no difference between them.

However, now drag and drop those two images into a word processor and you should see something like this:

enter image description here

Page-setting software like InDesign does the same thing. This is because in both cases the target environment is one that measures things in real-world units (centimetres or inches), so it uses the dpi metadata to decide how to convert your image's pixel dimensions to real-world dimensions. For example, a 600x600-pixel image at 300dpi will appear on the page at 2x2 inches.

By contrast, most screen-based environments (Photoshop, the web, etc.) measure things in pixels so no conversion is needed: each pixel in your image simply occupies one pixel of your screen.

So, if you're preparing an image for print on paper or other physical media and you're asked for a specific dpi (which will usually be 300), you should stick to it to ease the workflow at the print end. (Of course, a page designer can always convert your 72dpi image to 300dpi without losing anything, but why make things difficult?) Note that this only ever applies if your image is going to be placed on a page (for example, in a magazine or book), which is why it so rarely makes a difference. If you're just printing photos full-page (either on your own printer or sending off for photographic prints) the dpi will make no difference.

  • 1
    Furthermore, I think by emphasizing this as a "practical difference", it's very likely to perpetuate the myth among people who see the question and then just read your answer quickly without really understanding.
    – mattdm
    Jan 14, 2014 at 12:10
  • 4
    The answer opens with an introduction that says the gist of the entire answer: there is one small practical difference. It then states where there is no difference: in the pixels themselves and how they are displayed by most photo applications on a monitor. Only then does it move on to discuss the situation where ppi does matter: in word processors and desktop publishing applications. The illustration shows how the ppi affects the size of a photo within another document. The answer then restates that most screen-based environments measure in pixels only.
    – Michael C
    Jan 14, 2014 at 12:44
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    There is then a nice summary to end the answer: If the image is placed in a page it matters, if you are just printing full-page photos it doesn't.
    – Michael C
    Jan 14, 2014 at 12:45
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    Those who "...just read... quickly without really understanding..." will often get things wrong. There's not much you can do about that. I guess we could emphasize certain parts of the answer in bold font.
    – Michael C
    Jan 14, 2014 at 12:48
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    Matt: You're absolutely right, "it doesn't really matter". Nowhere do I say that it does. It's a minor issue of convenience for the person setting the page who asked you for a 6x4" image at 300dpi, that's all. I've tried to explain that as clearly and factually as possible. Any answer will be misread by a person who skims it, but the number of upvotes indicates plenty of people have found it helpful. Michael: Thanks for your comments. Jan 14, 2014 at 14:54

Does an image edited and saved/exported with 1200x800 pixels at 300 ppi look any different online than the same image saved/exported with 1200x800 pixels at 72 ppi?


A bitmap produced either on-screen or on paper from the image will be identical.

The only difference would be the default print size from some applications, and only then if the image size is not specified in any other way.

If you were to open the image in a simple image viewer (something akin to MS Paint that handles images, but not page layout, such as Adobe Illustrator) and press Print, you may find it sets the default print size based on the resolution, so the 300 PPI print would be 6x4" while the 72 PPI print would be 17x11"... assuming it didn't just auto-fit to the default paper size.

The only way to stop someone printing it at higher than 72 PPI on a 6x4" photo would be to only upload the image at 432x288 resolution.


As you wrote it, the answer is that there is no difference (until you print it or look at it in a document that will be printed).

First a clarification: PPI is pixels per inch, a description of the resolution of the image. DPI is dots per inch, a description of the physical ability of the printer/scanner being used.

pixels (on a side) = ppi x inches. multiply the two sides to get the total size of the picture, usually measured in MP (megapixels).

My local paper runs a section where people can submit their photos, and the instructions are that the pictures "must be at least 300 PPI". I've always been tempted to turn in a 300x300 pixel image at 300 PPI. This of course is low-res (.09 MP) and only prints at 1"x1", but would meet their posted requirements.

The assumption behind statements like this is that the image is a "reasonable size" when printed (like 4"x6" for example). In that case, 300 PPI means it would also look sharp (contain a lot of pixels, in this case 1200x1800=2.2MP), compared to 72 PPI which would look, well, pixelated at .1MP.

In your example they are measuring by pixels ("1200 pixels on the long edge"), not in inches, so then the PPI value is immaterial.

  • A careful reading of the question will show that ppi is used throughout, other than when quoting how others (mis)state it. The ppi field in the EXIF apparently must be populated with some number when the image file comes out of the camera to be compliant with the DCF standard.
    – Michael C
    Jan 8, 2014 at 18:21
  • @MichaelC and early versions of the EXIF standard specified that the default ppi should be 72 if no better value could be determined. It was really intended for scanners, not cameras. I think newer versions of the standard relaxed that requirement. Jul 16, 2021 at 3:04

There's no difference. The statements you are seeing are uninformed.

There are a lot of uninformed people on the internet, so that's not surprising. You haven't missed anything, except maybe you are overestimating the reasonableness of typical comments you might find online. :)

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    Something is WRONG on the Internet.
    – user
    Jan 8, 2014 at 15:02
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    @MichaelKjörling *Someone (yes, I had to make a comment for that, someone was wrong on the Internet :) Jan 9, 2014 at 9:16
  • @heinrich5991 Aw, drat. I never thought it would be me! ;)
    – user
    Jan 9, 2014 at 9:23

For completeness, I'll add an example when the PPI tag matters even without printing.

Some modern programming environments/platforms (for example, .NET WPF uses device independent pixels) do render images on the screen according to their PPI/DPI setting, rather than pixel-to-pixel as was always the norm. This is done in order to accommodate higher resolution displays, which are becoming more and more common.

If you want your image to be displayed pixel-to-pixel at least on normal screens (96 DPI in Windows), you need to save it with 96 DPI. (And even then do some tricks which are beyond the scope here). This still catches many a developer by surprise, who have a habit of always thinking in terms of pixels.

Then, like in the "real" world, using a high resolution display will not benefit this image and may even make it a bit worse, because it will be automatically upscaled according to the OS settings. On the other hand, one can realise these benefits by saving a 200-300 DPI image and rely on downscaling on "normal" displays.

This, of course, is mostly relevant for "graphics" in practice, but equally applies to photographs if they are used in the GUI.

  • I am not a developer, but the answer confuses me. First you mention that some environments use the ppi tag, then later on you write how the OS will upscale it on a high resolution display. If the OS compensates for it, is there then a remaining effect of the programming platform that tried to use the ppi? Jul 15, 2021 at 6:29
  • @Saaru, I didn't say the OS will scale, I said "according to the OS settings". Both can happen, and the issue is actually complicated. But the platform doesn't know the physical resolution of the display other than via the OS. Basically, "old" systems always output pixel to pixel; "newer" systems try to adapt to physical reality and scale even raster images.
    – Zeus
    Jul 15, 2021 at 8:32
  • ...And if the OS or the platform (doesn't really matter) decided to scale, it might as well grant the wish of the image to be displayed at a certain physical size, i.e. use its DPI tag. It doesn't have to happen: they could have decided to treat all images as 96 DPI (i.e. per-pixel on normal displays and scale up for higher resolution ones), but they didn't. I guess because this would prevent from using high-resolution images geared for better displays that downsample on normal displays (automatically).
    – Zeus
    Jul 15, 2021 at 8:39

I suppose that it depends on who is doing the speaking.

If the speaker has half a clue, you should understand their statement to mean that they're saving the image at the same dimensions but lower resolution. That is, if your goal is to provide a preview image that can't be used to make high quality prints, you save it as (for example) an 8"x10" at 72dpi instead of as an 8"x10" at 300dpi.

If the image that the speaker is saving turns out to be 24"x40" at 72dpi instead of 8"x10" at 300 dpi, you can assume the speaker has a fundamental misunderstanding of how images work.

  • What the question says is that the images are exported/saved at 1200x800 pixels (a 3:2 aspect ratio, by the way, not 5:4) with a ppi setting of 72 ppi or 300 ppi respectively. If printed at those dimensions obviously the 300 ppi version would be 4 x 2 2/3" and the 72 ppi version would be 16 2/3 x 11 1/9". But any remotely modern printing application will print a 1200x800 pixel digital image on 4R paper by resizing it exactly the same way.
    – Michael C
    Jan 8, 2014 at 7:05
  • @MichaelClark No argument. The OP has since edited the Q to include "and 1200 pixels on the long edge" in the alleged statement. That clarifies things somewhat and shifts the focus to what you're talking about.
    – Caleb
    Jan 8, 2014 at 7:48
  • @MichaelClark I humbly suggest that your comment here makes the accepted answer wrong. Of course it's true that some applications behave that way, but it has no real implications for image quality, especially when you include this clarification.
    – mattdm
    Jan 14, 2014 at 12:04
  • It's not an either/or Matt, it is both. The question asks in general if there is any practical difference between a 1200x800 pixel image saved with a ppi of 72 and a 1200x800 pixel image saved with a ppi of 300. One (of several) sub-questions asks if a 4R print will look any different. Another sub-question asks if there is any difference and if so, what?
    – Michael C
    Jan 14, 2014 at 12:27
  • The accepted answer addresses both of those sub-questions. This answer addresses neither, and in fact misstates the question to say the image is being saved at different, rather than identical resolutions.
    – Michael C
    Jan 14, 2014 at 12:29

I am learning web development and i encountered pixel unit in CSS and in reading about it i found these things.

There are two terms one is "software pixel" and one is "hardware pixel".

Software pixel is actually unit of length, its value is 1px = 1/96th in. Two screens of same dimensions will always have same software pixel. One software pixel can contain one or more hardware pixels depending on the device as you would have heard some devices have higher ppi(pixels per inch). ppi refers to hardware pixel.

Now come to printer, you have dpi, dpi here is the property of the hardware(printer). You can change it in the settings of printer. High dpi means printer would put more dots while printing and the image would look better.

Now while you are putting dpi info for an image (dpi=72 or dpi=300), it is a metadata(data about image) that concerns printer.

Now i don't know what constraints are there if you are selecting high dpi in your printer settings, for a vector graphics based image there is no issue in my opinion but i don't know about raster graphics based image. I am new myself, so if anybody knows what would happen if you select high dpi for printer and make dpi info higher for a raster graphics based image (which previously had lower dpi )please comment.

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    First of all, welcome!. You are mentioning an interesting new topic to the mix. The CSS px value. Unfortunately for everyone on the planet, we have not only "2 definitions" of a pixel. Software pixel and hardware pixel, but there are at least 3. I am trying to use the term "dixel" to the hardware pixel. "Dixel" for "display element". But that is another story. And then we are still left with the pixel as a matrix of data on an image, and a CSS pixel that messes up more the definitions, because a pixel has no intrinsic spatial dimension.
    – Rafael
    Dec 11, 2021 at 16:34
  • The 1/96 inch is a rough intent to solve the math inside the so-called "retina devices" to make the old px CSS unit backward compatible. This would be an interesting topic to analyze.
    – Rafael
    Dec 11, 2021 at 16:34
  • Many displays do have 96 pixels per inch. The very common 24" FHD monitor does, for instance. But many also do not. The current monitor I use most of the time, which is 27" at 2K, has a pixel pitch of 108 ppi.
    – Michael C
    Dec 13, 2021 at 7:25
  • @MichaelC ppi being different is not an issue. The thing is, does any web page looks different in terms of dimensions of content that is present on the web page, on two screens of same dimensions. Like you have two screens of exactly same size, one is HD and the other is Full HD. If you view a web page on both of them, will it look any different in way that content of web page is bigger or samller on one.I don't think so. While pixel unit is used in css to design the layout. Here pixel is software and unit of length and same for different ppi screens.
    – Seeker
    Dec 15, 2021 at 22:41
  • @Seeker Actually, yes it does make a difference. When my browser is set to 100% magnification (one screen pixel per one page pixel), items are smaller on my 27" 2K monitor with 108 ppi than on my 24" FHD monitor with 96 ppi.
    – Michael C
    Dec 16, 2021 at 23:17

As a professional photographer for 30 plus years I can assure you there are considerable differences between DPI values. It might be better to consider DPI as a factor about your final intentions for your photograph. As some choices are not reversible easily it is often sensible to keep two or more versions of your image . A lower 72 DPI version will display perfectly well on any social media and most pc's and TV's. However if you intend to make a print or take your image to your local colour lab then you will need a 300DPI version to use as the master copy to ensure you get the best result. The reason photographers choose raw format generally is to maximise the information in the image against the compression technology that occurs using JPEG format. Also you need to remember that even with the leaps and bounds of the new Ai software's for upscaling the simple rules are that you can easily down size your 300DPI image to 72 DPI without any problems , however if you try to bring your 72 DPI image up to 300 DPI you will loose a considerable amount of detail permanently . Hence you need to keep your 300DPI image as the master version and make all your other versions from it. There are many monitor screens running at 96 DPI these days so most pros save at 100DPI for social media and internet work .

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    Hi Tony and welcome to Photo.SE! Your answer appears to oppose the two high vote answers (and my own understanding of the matter). Why do you think a 300DPI image is better than a 72DPI image, given that both images have the same pixel dimensions (e.g. 3000px wide, 1500px tall)? Jul 14, 2021 at 12:19

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