The printers
SmugMug uses EZ Prints, a professional lab in Georgia that uses true continuous-tone printers to produce photos without visible dots. Inkjet and electrostatic printers, which simulate photo quality with half-tone dot patterns, need ten times the resolution to duplicate the same image crispness, highlights and shadow detail.
EZ Prints uses different printers, depending on the size of the print:
Prints up to 10x15 inches are produced on Fuji Frontiers or Noritsu Pros, both running at 302 dpi (dots per inch).
The rule of thumb is 150 dpi will produce superb prints but perhaps a very discerning eye with a magnifying glass may be able to distinguish added quality by going to 302 dpi on some images, particularly ones with sharp, high-contrast lines.
If you submit an image of higher or lower resolution than 302 dpi, EZprints will upsample or downsample your image to make them 302 dpi.
Prints above 10x15 are made on Durst Theta printers, which have a native resolution of 254 dpi.
What? Why would larger prints, which are more critical and more easily scrutinized, use a lower resolution?
Counterintuitively, larger prints require fewer dpi to look fabulous. There's a good discussion about why at Digital Grin.
Minimum requirements
To help customers, SmugMug's shopping cart only shows a print size if the original image meets our minimum resolution requirements for that size. Keep in mind that these are minimums. Please read "Recommended settings", below.
| pixels x pixels | pixels x pixels | pixels x pixels | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| wallets | 240 | x | 320 | 3.5x5 | 438 | x | 625 | 4x5 | 500 | x | 625 | ||
| 4x5.3 | 480 | x | 640 | 4x6 | 500 | x | 750 | 4x8 | 600 | x | 1200 | ||
| 5x5 | 625 | x | 625 | 5x6.7 | 500 | x | 670 | 5x7 | 575 | x | 805 | ||
| 8x8 | 800 | x | 800 | 8x10 | 800 | x | 1000 | 8x10.6 | 800 | x | 1070 | ||
| 8.5x11 | 850 | x | 1100 | 8x12 | 800 | x | 1200 | 9x12 | 900 | x | 1200 | ||
| 10x10 | 1000 | x | 1000 | 10x15 | 768 | x | 1024 | 10x20 | 1024 | x | 1280 | ||
| 11x14 | 768 | x | 1024 | 12x12 | 1200 | x | 1200 | 12x18 | 768 | x | 1152 | ||
| 16x20 | 1024 | x | 1280 | 16x24 | 1024 | x | 1536 | 18x24 | 1280 | x | 1600 | ||
| 20x20 | 1280 | x | 1280 | 20x24 | 1280 | x | 1536 | 20x30 | 1280 | x | 1920 | ||
| 24x36 | 1440 | x | 2160 | 30x40 | 1200 | x | 1600 | ||||||
Minimum resolution requirements for photo gifts can be found in our catalog.
Recommended settings
Suppose your photo is 2000x3000 pixels and you expect your admirers to order anywhere from 6" prints to 40" prints. What should you do?
Our recommendation is to leave it alone. EZ Prints will upsample/downsample as needed and they can do it better than all but the most serious experts.
We can feel your worry and doubt: "But...a 30-inch print is only 100 dots per inch..." We routinely show the following print at 80 dpi, 24x30 inches to passionate and fussy photographers. Their only comment about quality is "stunning":

We have only seen two prints in a million returned for too few pixels, and they were 400x600 pixel images from cheap consumer cameras, printed at 8x10. Here are the reasons prints are returned.