What resolution should a digital painting (in dpi) be for printing?

those lug nuts are just guessing. there's an actual formula to determine the proper dpi: 2 x lpi

lpi is not a typo or substitute for dpi. lpi is 'lines per inch' of your printer. don't bother looking for that info online or anywhere else because you'll never find it. but all consumer level ink jets are set at a standard 100 lpi. so following the formula you should set your dpi at 200. setting a higher dpi will result in greater sharpness but less tonal ranger. setting a lower dpi results in less sharpness but greater tonal range.

if you are scanning it gets a little more complicated but it sounds as if you are creating inside the computer. the links that soj_goj gave you are for scanning. not straight printing. for scans you simply multiply the 2 x lpi x (output size/input size) where output/input is a ratio. e.g. output=16x20 input=8x10. ratio=2/1 or just 2. so formula would be 2 x lpi x (2)=400dpi

p.s. if you happen to be using a laser jet they are set around 85 lpi. and if you are having your work professionally printed consut the print shop about their printer's lpi and go from there.

If you are going to print the common standard is 300 dpi minimum (higher for professional work) So if you set your canvas at 1000x1000, all you are going to be able to print at that level of detail is 3.33" x 3.33" You can tell it to print bigger and have a printer that does 300 dpi, but each pixel in your drawing will have to be doubled or tripled up to fill the page and the little fine detail in the corner of the eye where two fine lines come together will be a bit of a blob. The article you link to says rather plainly that if you can compute the pixels for your print size, then just use it - 8x10 at 300 dpi output is 2400x3000 pixels in the file. If it is a real nuisance to compute - your image has to be 6.35" x 7.85", then it is much easier to set the dpi to 300 (or some other value) and enter the size in those numbers and let it give you the working space. You are going to be setting line widths, etc, so they look good, and a line on 96 pixels per inch that is 3 pixels wide is just going to be 9 pixels (or 10 if it looks better) at 300 pixels per inch.

If I were you, I'd set it as high as it can go. The higher DPI will give you a better quality print. I recommend selecting a top-of-the-line scanner to digitize your analog art if you plan to go professional. I'd definitely stay above 600 dpi.

300 dpi is probably the best. It depends on the size of the print as well. This is usually best for regular size prints and magazines, etc.

Some people go as far as 1200dpi or higher for large prints

Here are some guidelines:

http://www.chin.gc.ca/English/Digital_Content/Capt...

http://www.rideau-info.com/photos/mythdpi.html

300 DPI will be good, but depends how much bigger you will like to print...because every DPI is good for some W x H.