DPI Doesn’t Matter! Pixels Do!

I have seen so many conversations on the Internet concerning what DPI people should set their photos to. It seems every idiot with a keyboard chimes in, and I’m about to become one of those idiots…

Let me save you the trouble of reading this entire article by summing it up in one sentence:

DPI does not matter.

Seriously. DPI does not matter for your photos. Leave it alone. Set it to 1. Set it to a billion. It does not matter. The only thing that matters is the number of pixels. The exact same 800×1000 pixel photo can be printed as 8″×10″ or 24″×30″. It’s the same pixels, just spread out over different distances. If you don’t have enough pixels, your printer is just going to repeat the same pixel enough times to match the size you’re printing, and you end up with blocky or blurry images. If you change your photo’s DPI in your photo software and it adds pixels, it’s doing the same thing as your printer—just repeating pixels and you end up with blocky or blurry images.

That pretty much sums it up, but for those of you who want to know exactly how all this works and play with some actual examples, keep reading.

What Matters Is Camera Pixels

Let’s say you have a beautiful photo of a grassy field. It’s 800×1000 pixels. That means if you zoomed in, you would see 800 columns and 1000 rows, and each box would have one color in it. At this zoom level, you realize that flower in the distance is nothing more than a couple of red boxes next to each other. Maybe there’s a bee on the flower, and it’s represented by just a single yellow box.

If you print your photo as an 8″×10″, that’s 100 DPI (800 pixels ÷ 8 inches = 100 dots per inch). You can print that same photo as a 24″×30″ poster at 33 DPI. But the pixels don’t change. That bee is still a single yellow pixel regardless of whether it’s printed at 100 DPI or 33 DPI or 1 billion DPI. You’re not going to get any additional detail out of a single pixel just because you changed DPI.

What matters is pixels.

If your camera takes that same photo at 4000×5000 pixels, that single pixel representing the bee expands to 25 pixels. With that increase, now maybe you can see black and yellow stripes. You can always shrink the larger photo down to a smaller size, but you can’t go the other way without a loss of detail. Merging that bee’s 25 pixels down to a single yellow one deletes all the black and yellow stripe data. You don’t get that data back when you enlarge it. You get that single yellow pixel 25 times.

Lookup Tables

Viewing Distance Determines minimum DPI

Your printer or software calculates the correct DPI automatically at the time of printing. You don’t need to calculate it. That 4000×5000 pixel photo prints 8″×10″ at 500 DPI and 24″×30″ at 167 DPI, regardless of what your photo’s internal DPI is set to.

By the way, those are both respectively excellent DPI choices for the print size, and here’s why…

We see less detail (less DPI) the further something is from us. For example, you might be able to read this article on your phone when it’s two feet from your eyes, but not when your phone is 20 feet away. There are calculations for how many dots per inch the average person can see at a specific distance (as well as the maximum the human eye is capable of seeing). I won’t go into all the details here, but read this article if you want to know more. Here are some common distances:

Distance DPI Max DPI Description
4 inches 876 2190 Closest adult eyes can focus
1 foot 300 720 Reading magazines, papers, etc.
2.5 feet 115 300 Viewing computer monitors
6 feet 50 120 Watching TV

The good news is that your poster-size print doesn’t need to be printed at 300 DPI. Most people are going to be viewing large prints from across the room. I can attest to this.

I have several 36″×24″ prints of my photos. Most were 5184×3456 pixels, which equates to 144 DPI (5184 ÷ 36). They’re hanging on my walls and look beautiful from across the room or even just a couple of feet away. At the one foot, the 144 DPI does show as a lack of clarity in the minute details. However, I’m the only one who gets that close; my guests don’t walk across the room and stick their face a foot away from my photos.

Pixels per Print Size

This is what actually matters—the pixels required to look good at a specific print size.

Small prints are generally viewed from 1–2 feet. Medium-size prints are typically viewed from a few feet. Larger poster-size prints are typically viewed from six feet or more, for which 50 DPI is acceptable (see table above). However, if viewers like your photo, they have a tendency to lean in for a closer look. Hence, I strongly suggest that you follow my Recommended Minimum column to handle a little more scrutiny.

Print Size Minimum for Viewing Distance Recommended Minimum
4"×6" 600×900 (150 DPI) 1200×1800 (300 DPI)
8"×8" 1200×1200 (150 DPI) 2400×2400 (300 DPI)
8"×10" 1200×1500 (150 DPI) 2400×3000 (300 DPI)
11"×14" 1265×1610 (115 DPI) 1650×2100 (150 DPI)
12"×18" 1380×2070 (115 DPI) 1800×2700 (150 DPI)
16"×20" 1840×2300 (115 DPI) 2400×3000 (150 DPI)
20"×24" 1000×1200 (50 DPI) 3000×3600 (150 DPI)
20"×30" 1000×1500 (50 DPI) 3000×4500 (150 DPI)
24"×36" 1200×1800 (50 DPI) 3600×5400 (150 DPI)

But My Printer Doesn't Have That DPI!

That’s OK. Your printer has algorithms to translate whatever it receives into the physical DPI that it can print. If it’s too large, like a photo that equates to 500 DPI sent to a 300 DPI printer, the printer automatically reduces it. If it’s too small, like 50 DPI sent to a 300 DPI printer, it has an algorithm to enlarge it.

Your printer manufacturer spends a lot of money to fine-tune those algorithms and produce the best print possible. But those algorithms can’t work miracles. They can’t take that single yellow pixel, know it represents a bee, and add the black strips when enlarging it. You need pixels for that, so make sure you’re using at least the recommended minimum in the table above.

Why Is 300 DPI the Standard?

300 DPI is the standard because that’s the resolution most people can see at the typical reading distance of one foot (see the first table above). Hence, virtually all printers print at a minimum of 300 DPI. Many printers can print 600 DPI or higher, but that is overkill for the average viewing distance.

Why Do I Keep Seeing 72 DPI?

72 DPI is a carry over from the 1980s when computer monitors were 72 pixels per inch (PPI), which mirrored the typography standard of 72 points per inch. These were the standards as the Internet blossomed in the 1990s. Thus, 72 DPI, or rather 72 PPI, became the de facto standard for online photos.

All modern computer displays and smartphones are much higher resolution than 72 PPI. They are commonly over 200 PPI with some over 500 PPI. Unfortunately, 72 DPI/PPI is so embedded in operating systems, applications, and the web that it is the assumed metric.

Examples

Same Pixels,
Different DPI

Here’s an example of different DPIs. The left image is at 24 DPI; the right is at my camera’s default of 240 DPI. Both have the same pixels, 400×500, and both have a file size of 316KB.

Note that one side is not 10x better or more detailed than the other side. The pixels are exactly the same.

400x500 pixels at 240 DPI 400x500 pixels
at 240 DPI
400x500 pixels at 24 DPI 400x500 pixels
at 24 DPI

Identical Pixels
24 DPI vs. 240 DPI

Different PixelS,
Same DPI

Here’s an example of different dimensions but the same DPI. The left image is 40×50 pixels* with a file size of 7KB; the right is the original 400×500 pixels and 316KB. Both are at 240 DPI.

Here, you can clearly see the right side is has more detail. That’s because every 100 pixels on the right (10×10 grid) is represented by only one pixel on the left. DPI is the same.

Like I said at the beginning:

DPI does not matter.

Pixels matter.

400x500 pixels at 240 DPI 400x500 pixels
at 240 DPI
40x50 pixels resized to 400x500 pixels 40x50 pixels
at 240 DPI

40×50 pixels vs. 400×500 pixels
Identical DPI

*Note that the 40×50 image was upscaled back to 400×500 for the comparison to avoid browsers’ built-in upscaling algorithms that smooth the pixelization (the pixelization is point of the comparison). See the next section for algorithm examples.

Algorithm Smoothing

Like I’ve said repeatedly in this article, enlarging a photo does not magically add black and yellow stripes to that single yellow dot representing a bee. But I did mention there are some printer algorithms that try to smooth things out.

Here are real world examples using my bat photo and the algorithms included in your browser. Photoshop offers similar resampling algorithms when resizing images.

If everything goes right in your browser, the left side should have an algorithm applied that smooths the blocks inherent when enlarging images. However, it can’t tell that a particular block represents hair or wrinkles or a nose. Those details are lost. Instead, the algorithm looks at the surrounding blocks and guesses what the general shape should look like. I have to say that it does an impressive job considering it has none of the details of the above photos to work with.

40x50 pixels resized to 400x500 pixels 40x50 enlarged
without smoothing
40x50 pixels at 240 DPI 40x50 enlarged
with smoothing

40×50 enlarged to 400×500
Algorithm smoothed vs. Pure enlargement

400x500 pixels at 240 DPI 400x500
Original
40x50 pixels at 240 DPI 40x50 enlarged
with smoothing

Algorithm smoothed vs. Original

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17 Responses

  1. This article keeps referring to DPI where in many cases it means PPI. So, although it is correct in many ways, it ends up adding to the the confusion and misunderstanding it was intended to clear up.

    Pixels per inch (PPI) are what is input to the printer. Dots per inch (DPI) are what the printer puts on the paper. With typical inputs ranging from lower than 100 PPI to a high of 600 PPI modern inkjet printers typically print several dots for each pixel.

    It is the pixel density (PPI not DPI) that sets an upper limit to the amount of genuine detail in the printed image. [Whether that limit is reached depends on how much detail was actually captured by the lens and the photographer’s technique. But regardless of the number of pixels available it is the amount of genuine detail in the image that determines how large it can be satisfactorily printed. The less genuine detail in the image the more PPI are needed to produce a print that will look good from close up. Whether all the available detail appears in the final print then depends on how the printer’s software and available inks maps pixels to coloured dots, and the paper on which the print is being made].

    As for what the PPI should be, the figure of 300 is bandied about on the net as the maximum resolution that most people can distinguish from close up. [i.e. any more pixels would be wasted, as the eyes are incapable of seeing the extra detail] and, therefore, as an ideal to be aimed for.

    This is nonsense, but that has not prevented it from being repeated al over the internet, and in many cases i is obviously by people that are uncritically repeating what they have heard, with little or no hands-on experience.

    So the number of pixels does not determine the amount of detail in the photo. It is merely an upper limit. If the lens is delivering less data than the sensor is capable of capturing then the pixels capture the data with fewer artefacts, but they do not add any data. And if the scene itself is lacking in detail the best lens and a sensor with lots of pixels cannot add more detail.

    Also, making a good print at fewer than 300 PPI is not, as the self-professed experts would have you think, just about the viewing distance. The content of the image makes a difference. Some images look as good as they are ever going to at 100 PPI. Others may even need more than 300 PPI if they are going to stand up to examination from 5 or 6 inches away.

    And there are yet more variables. A printer with a 12 ink system is going to give better tonal gradation than the typical 4 ink desktop printer, and a glossy coated paper is going to show up insufficient pixels at higher densities than a rough surfaced “Art” paper.

    A lot of skill, knowledge and experience goes into making a stunning digital print. The internet promotes the idea that we can all produce wonderful prints just by following a simplistic rules (print at 300 DPI … whoops … PPI …. or look up the “correct” PPI for the intended viewing distance). It just isn’t so. These are no more than hints at what might be a good starting point to figure out how big you can print with the pixels at your disposal. But the realities of the art of printing are more complex and subtle.

    1. Hi, Tom! I agree with just about everything you said.

      Yes, I do use DPI when PPI would be more appropriate, but that was intentional. Most layout and image editing software refers to that arbitrary metadata setting as DPI (although recently Photoshop has started calling this “Resolution”). My target audience was all those people who get confused by this DPI setting and post online asking what they should set it to, followed by a lot of misinformation just like you said. Plus, there’s a particular magazine editor who long ago somehow drastically reduced the resolution of one my photos, went to press with the low-res version on a full two-page spread, and then tried to blame me because “my image’s DPI wasn’t set right.” (Ultimately, she apologized.)

      As you mentioned, there’s a lot more to both capturing and printing an image. Naturally, a better lens is going to capture a better photo; a better printer is going to produce a better print. All of these are outside the scope of this article, and frankly irrelevant to a photo’s DPI metadata setting.

      The point is exactly what you said and I mentioned several times—detail. A 5000×4000 photo is going to have more detail than the same photo at 500×400 (assuming you didn’t just make the 500×400 larger). 😉 That internal DPI metadata doesn’t add or remove detail but changing pixel count does, as shown by my comparisons above.

      By the way, there is scientific basis to resolution vs. viewing distance. Granted, most of the “self-professed experts” online are just regurgitating forum posts. However, I actually have read quite a few scientific studies on the subject. I linked the most relevant one in my article. If you have a study that shows these numbers are nonsense, I’d love to read it and possibly reference it in my article.

  2. Hi Bennett,

    Thanks for the cool and informative article. Love it.

    But I have a question which I have tried to search online for hours and yet to have a responds. So I am hoping you could help.

    I’m using Panasonic G7 which is 16MP. Taking one of the pictures that I have for example. After editing, the properties from the picture are:
    Dimension: 4208 x 3464
    Width: 4208 pixel
    Height: 3464 pixel
    Horizontal resolution: 300 dpi
    Vertical resolution 300 dpi
    File size: 8.86 MB

    After putting in my Signature (watermark), it reads:
    Dimension: 4208 x 3464
    Width: 4208 pixel
    Height: 3464 pixel
    Horizontal resolution: 96 dpi
    Vertical resolution 96 dpi
    File size: 1.35 MB

    So both of the pictures have identical pixel counts but the dpi are different. Will I get a lower quality photo print for the picture with lower dpi?

    How did you make your picture to have different dpi but same file size? I thought dpi are the amount of (color) information of the picture and the more dpi there is, the bigger file size it will be.

    Thanks for your advice. 🙂

    1. Hi, Edward. The DPI won’t affect anything here. Dimensions are the same. However, your images are dropping from 8.86 MB down to 1.35 MB, thus your software is reducing the JPEG quality. It’s so low that you will probably see “artifacts”, which are blocky areas in the compressed photos. I didn’t cover JPEG quality in this article; that’s a whole other subject, but I’ll provide some pointers here. You don’t mention what software you’re using to add the watermark, but likely it will have a JPEG compression setting somewhere when you save or export the image. The higher the percentage, the better the quality, but the larger the MB. Usually, 40–60% is a good compromise for web images; 80% is good for prints. Personally, I use 85% for my photos. I picked that after extensive comparisons of my original RAW to various percentages. I found that the common 80% still produced some very minor artifacts, but at 85% there were virtually none, and anything higher just increased my file sizes with no discernible visual difference. YMMV.

      1. Hi Bennett,

        Thanks for reply. I’m using some freeware that I found online to do a mass watermarking on my pictures.

        So, the dropping in size does affect the print quality. Hmmm… do you have any recommendation on which software should I use to watermark my photo which will not affect the print quality?

        Once again thanks for taking time to reply me. 🙂 Greatly appreciated.

      2. Hi Bennett,

        Thanks for your reply.

        I’m using uMark for the watermarking and also I have tired converting it to JPG with 100% quality retention, but still my picture’s size decreased from 7.11MB to 4.28MB.

        Is there anyway/recommendation on what I should do; or which software I should use so I could retain the quality and size of my picture? Thanks.

        1. Looking at this a little closer, the Panasonic G7 supports RAW. Thus, I assume your original 8MB photos at 16MP are shot in RAW. That’s great! I recommend always shooting in RAW so you get the actual sensor data. That allows superior color correction, post-processing, etc.

          That said, uMark is likely doing fine with its compression. No need to change your watermarking software.

          Also, as I said earlier, 80-85% quality is good for JPEGs. It’s what I use for all my printed photos. However, note that JPEGs are always “lossy” (loses image quality/data), even at 100%. This is fine for photos. However, if you want absolutely no data loss, use a lossless format like PNG or TIFF (lossless formats are preferred for things like line art and logos).

          1. Hi Bennett,

            Thanks for your reply again. Have a good day and weekend! Please keep up the good work (in making contents like this)!

  3. Hello,
    I recently had some old film processed. The scans returned to me are 72 dpi and appx. 2000×3000 pixels. The service charges a fee to get your images returned on a disc at 300 dpi. I downloaded and saved these 72 dpi scans. If I plan to print these images in the future should I get the extra disc or does it matter?

    Thank you

    1. Like title of the article indicates, DPI doesn’t matter. There is no benefit to getting the same resolution at 300 DPI. The only reason to pay the service fee is if the *scanned* resolution is greater than 2000×3000. E.g., the scans are actually 4000×6000, and it costs extra to get this larger resolution, otherwise they reduce it to 2000×3000.

  4. Hi Bennet,

    As an example, one of my cameras is a Canon 1D Mark IV (16px) which I shoot at Large Jpeg 4896 x 3264 @ 72dpi. I do all my editing at this original size on a duplicate keeping the original image unedited. Upon finalization of the edit on this duplicate I usually will make two more duplicates, one of which I will size to 300dpi for print @ 9 x 13.5in, the other i would downsize the image to 9x 13.5in @ 72dpi. Am I doing this correctly? I do the same with my 5D Mark II Full Frame. I noticed a photog sent me his original image for editing, shot on a Nikon, NEF file, and the dpi was 300dpi. Do you think this is a standard setting for a NEF file? I actually had some difficulty cleaning and editing his images, they were not sharp. I edit in Adobe Photoshop CC, Lightroom Classic and Affinity. I do want to hurt his feelings nor look foolish when I need to bring this subject up. Thanks

    1. I’m sorry for the delay in replying.

      You don’t need to make multiple copies with different DPIs. As my article states, DPI is an arbitrary metadata setting. The only thing that matters in terms of resolution is pixels. Ignore the DPI and keep the pixels at their original maximum (e.g., 4896 x 3264 pixels). The only time I change my resolution is cropping or when I need a lower resolution version for something like a web page. My Canon tags its RAW files at 240 DPI. I have never changed it because it doesn’t matter.

      As for your photographer’s NEF files, as long as you haven’t been tinkering with DPI or resolution after importing, the NEF is going to be the best original version you can get. I can’t comment further without knowing a little more. Maybe the photographer had a bad day. Maybe the autofocus was off. Tough subject to shoot. Tough location. I can understand all of that. As a cave photographer, my lens and camera regularly fog up, get covered with dust, splashed with water, smeared with mud, blindly shooting from angles where I physically can’t position my body. Regardless, the DPI setting has absolutely NO affect on photo clarity, so that’s not the issue.

  5. Hi all. This is all about photography which is an image that has a lot of built-in information. Does this same concept apply to graphic design where you start with a blank canvas and add the content, be it a single pixel or millions of pixels? Even if it does, is it not best practice to create anything for print at a minimum of 300 ppi if it is not vector?

    1. Yes, you’re absolutely right. This article is about images with a fixed number of pixels, like photographs. In contrast, vectors, such as artwork created in Adobe Illustrator, are entirely different. Vectors are mathematical formulas that describe shapes. When you rasterize vectors (e.g., export to JPEG/PNG or print), you are converting these formulas to blocky pixels. At this point, you need to know your target output, like printing a 1×1 inch logo on a business card. I agree with you that the minimum in this circumstance should be 300 DPI, which gives you a 300×300 pixel image. But what if the vector art is going on a 40×12 foot highway billboard? That’s where viewing distance comes into play. My table above doesn’t list billboards, but 300 DPI is definitely overkill for that.

      Ideally, you want to leave your vectors as vectors. Embed the actual vector in your documents instead of a blocky rasterized image. Send the vector file to your printshop. That way vectors stay in their ideal mathematical representation right up until the time of printing when its target DPI gets negotiated between the vector application and the target printer.

      However, if you do decide output your vectors to a rasterized image, by definition you are now dealing with a fixed number of pixels. Hence, this article applies and DPI no longer matters. (What’s unique with vectors is that if you need more pixels, you just export again with a larger resolution, which is not possible with the bat photo examples above. Even so, all these outputs are ultimately still a fixed number of pixels.)

  6. Great artice Bennett. Thanks for all your effort to explain. My question is if I shoot raw and the image arrives in photoshop as 300 dpi and i cut the dpi to 150to get more pixels hence a larger printed image have I lost half the resoulution detail?
    Thank you for your reply, Edward McHugh

    1. Just be sure that the resolution (width and height) stay the same. Unfortunately, when you cut the DPI from 300 to 150, Photoshop will automatically cut the resolution in half, too (e.g., from 4000×3000 to 2000×1500). To fix, first copy one of the original resolution settings (e.g., 4000), then change the DPI, and finally paste the original resolution setting back (the other resolution setting will automatically reset).

      By the way, a few days ago I would have said that you shouldn’t need to touch the DPI in Photoshop at all. However, just this past weekend I ran into a problem combining images with different DPIs directly into Acrobat. Page sizes were different based on the image’ embedded DPI. (One of the only instances in which DPI still matters–calculating page size given a DPI and specific number of pixels.) I could have tweaked page sizes in each document, but easiest fix for me was to change the DPIs in Photoshop and Lightroom before combining into Acrobat.

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