What dpi should I be using for prints?

This is a complicated topic. But it boils down to this: basically, there is no difference between 300dpi and 72dpi!

For example, a 12 mexapixel photograph made at 300dpi will make an acceptable print about 9.5 inches by 14 inches in size. The same photograph, at 72dpi, would be about 40 by 60 inches. Stand back at normal viewing distance from either photograph, and the will look about the same. That might be hard to believe, but it's true.

That is all your really need to know. Don't worry about dpi.

But if you want to know a little more, here it is:

- Your local vendor shouldn't be asking for a particular dpi. The vendor gets the photograph from you as a digital file, and then the vendor makes the print for you, at the print size you ask for. As the vendee, you should have NO concern about dpi, unless you've cropped away most of the photograph to begin with, meaning there might not be enough pixels to work with. The vendor should tell you if there is a problem, though.

I speak with some knowledge about this topic, as I've periodically submitted digital photographs for publication. The publisher usually asks for a file size that is the equivalent of 300 dpi. Why? Because that's the standard figure publishers have settled on in the publishig world.

For example, my book publisher asked for files with a minimum of 300dpi and added the minimum size necessary in inches: 8.5x11. The publisher could have asked for 72dpi at 35x45 inches, which would have been the same as 8.5x11 at 300dpi. The size of the pages in the book were 8.5x11 inches. A publisher will, in fact, often print at considerably less than 300dpi, but asking for a file with 300dpi allows, among other things, the ability to crop out some of the image while still retaining high enough resolution for a print.

So, for you, dpi is irrelevant, whether you burn your photograph to a CD or send it to the vendor as an online file.

This is a complicated topic. But it boils down to this: basically, there is no difference between 300dpi and 72dpi!

For example, a 12 mexapixel photograph made at 300dpi will make an acceptable print about 9.5 inches by 14 inches in size. The same photograph, at 72dpi, would be about 40 by 60 inches. Stand back at normal viewing distance from either photograph, and the will look about the same. That might be hard to believe, but it's true.

That is all your really need to know. Don't worry about dpi.

But if you want to know a little more, here it is:

- Your local vendor shouldn't be asking for a particular dpi. The vendor gets the photograph from you as a digital file, and then the vendor makes the print for you, at the print size you ask for. As the vendee, you should have NO concern about dpi, unless you've cropped away most of the photograph to begin with, meaning there might not be enough pixels to work with. The vendor should tell you if there is a problem, though.

I speak with some knowledge about this topic, as I've periodically submitted digital photographs for publication. The publisher usually asks for a file size that is the equivalent of 300 dpi. Why? Because that's the standard figure publishers have settled on in the publishig world.

For example, my book publisher asked for files with a minimum of 300dpi and added the minimum size necessary in inches: 8.5x11. The publisher could have asked for 72dpi at 35x45 inches, which would have been the same as 8.5x11 at 300dpi. The size of the pages in the book were 8.5x11 inches. A publisher will, in fact, often print at considerably less than 300dpi, but asking for a file with 300dpi allows, among other things, the ability to crop out some of the image while still retaining high enough resolution for a print.

So, for you, dpi is irrelevant, whether you burn your photograph to a CD or send it to the vendor as an online file.

Jamie,

As iDave stated, the DPI number that your picture indicates is not necessarily relevant to your printing process. What is important is how many pixels you have to work with.

That 300 DPI is a somewhat magical number, dealing with physics and human anatomy. At normal reading distance (something like 16 inches?), the average human eye can tell differences if a picture is printed at less than 300 DPI. That is, your eye is can resolve up to 300 DPI at reading distance.

To find the DPI, there is no setting. Take the number of horizontal pixels in your picture (let's say 3000), and divide it by the horizontal size of your photo (Let's say 6 inches if you are printing 4x6). That photo can have 500 DPI, when printed, if the photo printer supports resolutions that high. 500 DPI is greater than 300 DPI, so your eyes will be happy. They will be just as happy as if you had printed with 1800 pixels wide, which is 300 DPI. If you print out a photo that is 1200 pixels wide to a 4x6 print, you will have 200 DPI, and your eye will tell that things aren't really quite crisp.

So, taking the math the other way, if you are printing 4x6 prints, you would want the long dimension to be at least 6x300=1800 pixels. In other words, don't crop a photo to less than 1800 pixels wide and expect it to print sharply. Also, don't use an Aperture export option that reduces the number of pixels ("TIFF - 50% of original size") if your original was less than 3600 pixels wide.

All this math of course has nothing to do with the quality of your original. If your original wasn't in focus, printing it as a 4x6 with 300 DPI will look out of focus. If you threw away a lot of pixels because it's a low quality JPEG, you won't get those pixels back and the photo may look blocky at any size.

This also says nothing about how good your eye really is, too, and how far away you will be when viewing your prints.

Hope this makes sense,
nathan

Jamie
for print yes the DPI does make a difference, for screen use and video use, dpi is irrelevant and the pixel dimension are critical. When going to print the majority of printers give optimum results when the file is 300dpi for the print dimensions. (DPI= how many Dots Per Inch the printing device is able to lay down, your digital file needs to provide 1 pixel for each "dot"
(nb. this is different to the measurements used in inkjet printers, which each typically have an optimum requirement of between 200dpi & 300dpi)

The confusion arises up when designers and printers ask for a 300dpi file, they need it 300dpi for the print size.


so to answer each point.

1. 300dpi does make a difference. If you are exporting a file for a 5x7 print and specify 72dpi, it will look terrible, as the file size will be

5"x72px & 7"x72px = 360px x 514px

whereas exporting to file at 5"x7" using the 300dpi setting, your file will be

5"x300px x 7"x300px = 1500px x 2100px

2. Unable to answer this, however the Kodak Photographic paper printers expect a 300dpi file.

3. Giving files to someone else for print, yes export them at 300dpi.

Just to confuse you, as the previous posts have mentioned if you are doing the calculations in your head and exporting using pixels dimensions rather inch/cm dimensions the dpi is nice but has no effect on the file size.
eg. rather than inputting 5"x7" @ 300dpi, you input, 1500px x 2100px.

Who said photographers do not need Maths?

Tony

I'm gonna stick with what I said.

This is a complicated topic. But it boils down to this: basically, there is no difference between 300dpi and 72dpi!

For example, a 12 megapixel photograph made at 300dpi will make an acceptable print about 9.5 inches by 14 inches in size. The same photograph, at 72dpi, would be about 40 by 60 inches. Stand back at normal viewing distance from either photograph, and they will look about the same. That might be hard to believe, but it's true.<</div>

So, Tony, if you have a 12 megapixel camera, and you want to to print to 10x15 inches at 300dpi, you won't be able to send the file to your printer, because you won't have enough pixels.

You could upsize the your image with software, but you don't have to bother, because you don't need 300dpi from a 12 megapixel camera to print a 10x15 inch photograph.

Send your printer your file at maximum resolution (and we'll presume you are making your photographs with your camera set to record at maximum resolution). If there's a problem, your printer will tell you.

Even Apple will tell you. Try to send a file from a 2 megapixel camera online to Apple, and ask that it be printed as a 16x20. Apple will warn you your file is too small to create a print that size. You won't have that problem with a four megapixel camera. Apple, Kodak, Walgreens, Costco, don't ask you to provide them with files that are at 300dip. You simply hand over your file, or stick your card or CD into a slot, and the machine does the rest.

Many thanks for your help, guys. I'm going to stick with 72 dpi for now. Thanks again!