The Best Resolution for Printing Photos

Photoshop Print Settings
© S. Chastain

Whether you're scanning a document or choosing a digital camera, it's easy to be confused about the number of pixels you need in an image. In fact, most SLR digital cameras capture images at a resolution of 300 pixels per inch, which is great for an image destined for a printing press. Still, there is a lot of focus on resolution, especially in the marketing of cameras and printers.

First, it's important to understand a few terms that relate to image size and resolution: PPI (pixels per inch), DPI (dots per inch), and megapixels. If you're not familiar with these terms or you need a refresher, follow the links below for more detailed explanations.

  • PPI: A measurement of image resolution that defines the size at which an image will print. The higher the PPI value, the better quality print you will get — but only up to a point. Generally, 300 PPI is considered the point of diminishing returns with inkjet prints.
  • DPI: A measurement of printer resolution that defines how many dots of ink are placed on the page when the image is printed. Today's photo-quality inkjet printers have DPI resolution in the thousands (1,200 to 4,800 DPI) and produce acceptable-quality photo prints of images with 140 to 200 PPI resolution, and high-quality prints of images with a 200 to 300 PPI resolution.
  • Megapixels (MP): One million pixels, though this number is often rounded when describing digital camera resolution.

When determining how many pixels you need, it all boils down to how you will be using the photo and the dimensions of the print. Here's a handy chart to help you determine how many pixels you need for printing standard-size photos on an inkjet printer or through an online printing service.

5 MP = 2592 x 1944 pixels | High quality: 10 x 13 inches | Acceptable quality: 13 x 19 inches

4 MP = 2272 x 1704 pixels | High quality: 9 x 12 inches | Acceptable quality: 12 x 16 inches

3 MP = 2048 x 1536 pixels | High quality: 8 x 10 inches | Acceptable quality: 10 x 13 inches

2 MP = 1600 x 1200 pixels | High quality: 4 x 6 inches, 5 x 7 inches | Acceptable quality: 8 x 10 inches

Less than 2 MP | Suitable only for on-screen viewing and wallet-size prints. See: How many pixels do I need for sharing photos online?

Greater than 5 megapixels | When you get beyond 5 megapixels, chances are you are a professional photographer using high-end equipment, and you should already have a handle on the concepts of image size and resolution.

Megapixel Madness

Digital camera manufacturers would like all customers to believe that a higher megapixel count is always better; however, as you can see from the chart above, unless you have a large-format inkjet printer, anything greater than 3 megapixels is more than most people will ever need.

Sometimes, though, more megapixels come in handy. They can give amateur photographers the freedom to crop more aggressively when they can't get as close to a subject as they would like. The tradeoff is larger files that require more space in your camera's memory and more disk storage space on your computer. The cost of additional storage is likely worthwhile, though, especially for those times when you capture that priceless photo and want to print it in a large format for framing. Remember, you can always use an online printing service if your printer can't handle large-format prints.

A Word of Caution

A lot of information is being presented here, but the most critical thing for you to understand is that you should not increase the PPI value of a photo simply by increasing image size and resolution values in Photoshop or other image-processing apps.

The first thing that will happen is that the final file size and image dimensions will increase dramatically. The problem is that the color information in those new pixels is only a "best guess" on the part of the computer, thanks to the process of Interpolation. If an image has a resolution of 200 PPI or less, it just shouldn't ever hit a press. For more information, see How do I change the print size of a digital photo?

— Updated by Tom Green