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Trevor.Dennis
Community Expert
Trevor.DennisCommunity Expert
Community Expert
February 16, 2026
Question

How Many DPI For Large Prints?

  • February 16, 2026
  • 3 replies
  • 0 views

I’ve just watched this video, and had to share.  How many posts have we seen over the years from confused users who are adamant that they need 300DPI for the billboard sized print they are making?  

Simon d’Entremont had done a double blind test with large prints printed at a range of resolutions, and viewed at various distances.  [Spoiler] Neither he or his friends could tell the difference even when viewed from just 12”.  I will be bookmarking this for the next time someone asks the question, or insists they need a Quadrillion pixel file for their A0 print on semigloss paper.

 

      3 replies

      Per Berntsen
      Community Expert
      Per BerntsenCommunity Expert
      Community Expert
      February 16, 2026

      I routinely make 33 x 44” prints from from digital medium format.
      The pictures are taken with a tripod at f/8 with high quality lenses, and I use focus stacking, so every part of the image is sharp. I want to preserve this sharpness even when viewing the prints up close.

       

      I have found that 180 ppi is required, but if I don’t have enough pixels, I can get away with 150.
      The difference is barely perceptible.
      I use an Epson SC-P8000.

      Chuck Uebele
      Community Expert
      Chuck UebeleCommunity Expert
      Community Expert
      February 16, 2026

      I never got technical when I printed large print. All I know is that when I printed 30"X40" prints, my system couldn't handle 300dpi. I usually dropped it to 150 or 100 dpi and had no issues with sharpness.

        davescm
        Community Expert
        davescmCommunity Expert
        Community Expert
        February 16, 2026

        It is less about sharpness and more about whether you can see the pixel structure at a normal viewing distance. With very good eyes, you will struggle to see pixels at 130ppi from 50 inches which would be a normal distance for such a large print. In short, the math supports your real world findings.

        If you have a good sharp image out of a modern camera, there is a good argument to increase image print size without resampling. At a normal viewing distance you will see no difference and there will be no resampling artifacts. 

        Dave

        davescm
        Community Expert
        davescmCommunity Expert
        Community Expert
        February 16, 2026

        A bit of math for those that insist they can still tell the difference (I’ve posted this before in the old forums).

        A good human eye can resolve 60 line pairs per degree i.e. pairs of black and white lines.  So in half a degree that would be 60 single lines.
         

        Simple trigonometry means that the width containing those 60 lines can be calculated by:
                       Width of 60 lines = Viewing distance x tan(0.5°)

        Knowing the width for 60 lines (or pixels), how many lines per inch can be seen by using 60/Width of 60 lines can be calculated.

         

        So putting those together gives : 

        maximum visible ppi = 60/(Viewing distance x tan(0.5°)) = 60/(Viewing distance x 0.0087269) = 2/(Viewing distance x 0.000291)    

        Or

        maximum visible ppi = 1/(Viewing distance x .0001454)

        Or

        maximum visible ppi = 6878/Viewing distance

        So as an example, for a print viewed at 36 inches, ppi = 6878/36 = 191ppi. Anything above that is wasted as even good eyes will not resolve it. In practice, we do not print black and white lines so the real world requirement is even less as shown in the video Trevor linked.

        Dave

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