Whether you’re an artist, business owner, marketer, or photographer you’ve probably come across the terms dots per inch (DPI) and pixels per inch (PPI) at some point when using digital displays, capturing images and printing digital image files.
Many people incorrectly believe that these terms DPI & PPI are simply two different ways of describing the same thing. Although they function in a similar fashion, PPI is not DPI and shouldn’t be used interchangeably.
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Dots and Pixels in Basic Terms
A dot is a physical printer-based element. It refers to the smallest detail visible to human eyes, as a unit of measurement in a dot or other shape, that a printer can print out on a page to recreate content from a photo or document. A pixel is a physical digital-based color or light element. It refers to the smallest detail visible to human eyes, as a unit of measurement in a square or other shape, that an image capture device or digital display, such as a camera, scanner or computer monitor, shows as an image or saves as an electronic file.
Both are related to the resolution. Dots per inch (DPI) refers to output resolution since the fineness of image details is expressed as the output of a printed image. Pixels Per Inch (PPI) refers to input resolution as the details related to the input of data during image capture and on-screen manipulation.
These terms often cause people to become confused because they use them incorrectly when talking about electronic files and printouts, especially since image size and resolution in terms of PPI can impact printout quality & print size.
The Differences in Per Inch Standards
Image Credit: © Wapcaplet/CC BY-SA 3.0
Both dots and pixels are expressed as “per inch” measurements, which means that a DPI or PPI number describes the total number or density of either that related hardware and software can express or insert in a one inch space. No more dots or pixels can appear in a 1-inch area than allowed by the screen, image capture technology, saved image file, or printing technology.
DPI
Printers create detail via dot density in the form of lines, which people describe in terms of one inch area measurement. The standard dots per inch (DPI) setting to create a higher quality printout is 300 DPI or greater. With a higher DPI, you can achieve a detailed, sharp image that doesn’t appear as fuzzy, blurry or pixelated on printed paper as seen with a smaller DPI. The print quality relies on both the data contained in the electronic file sent to the printer and the printer’s hardware and software. If you attempt to print at a low DPI (150 DPI or less, then you won’t get a high-quality printout of the image since the printer uses fewer dots to recreate it on paper.
PPI
Digital displays such as computer monitors create detail via pixel density on your screen in horizontal and vertical lines, which people describe in terms of 1-inch area measurement. The image size of any captured digital image and file and the related number of pixels are critical to both display screen and print quality. A large image made up of more pixels, typically created by selecting the best picture quality or highest image size setting on an image capture device, appears sharper onscreen and prints out with less distortion than a smaller image containing fewer pixels.
DPI and PPI Issues
No matter whether you want to display, manipulate or print one or more photos, you need to make a decision about digital image quality. Some digital image capture devices simply can’t capture a lot of details and produce low resolution image.
High-quality image technologies can capture more details even if you’re not close to a subject and make it possible for you to create macro photos of tiny subjects as large photos at a higher resolution. If you want to display, alter, store or print high-quality photos and text, the equipment you use matters.
A low-res image and associated files are fine for tasks that don’t require the best printout quality, such as reproduction of a text document for yourself or your employer. A lower dots per inch (DPI) can save you money since you don’t need as much printer medium, such as ink or toner, to make hard copies of documents.
That said, low-res pictures are horrible if you want to impress others in academic, business, artistic or other important scenarios. Many people use medium-res (200 DPI to 300 DPI) to make a good impression, as seen with personal and professional letters, fancy invitations and marketing and promotional materials. They use sharp, high-resolution (300+ DPI with an average of 600 DPI) to make the most positive impression possible, as seen with portrait personal and professional photographs.
Important reminders:
- To produce high-res pictures saved at a high PPI to achieve high dots per inch (DPI) printing takes up more hardrive space than low-res ones.
- Many email service providers limit the actual size of files you can send as attachments via email, which means that you might have difficulty sharing high-res files via that route.
- Unless you’re an artist or photographer, you don’t need to go above 600 DPI since image sharpness seems to change little when viewed with human eyes after a certain point except for those who zoom in and make changes to digital images on a pixel-by-pixel basis.
- Image edits made in computer applications can alter the DPI, which means that if you change the image size or increase the number of pixels, you might suddenly have an image that’s too large to print without extreme distortion.
- Printer mediums can impact final print quality and counteract a larger DPI, as seen when ink from certain inkjet printers bleeds in general or when used with certain materials.
- Printing photos from the internet or a computer screen or a video display screen requires a high DPI printer because the printed image usually don’t translate well, and most printers have a limited range of colors don’t have the ability to reproduce all the color combinations available. Instead, they layer ink or toner in gradient degrees that somewhat recreate intensity or shades to make colors appear even.
This guide obviously only goes over the basics of both of these terms. Photographers, artists, business owners and others should explore any specific complex DPI and PPI measurements and requirements for various types of common projects, as needed. A high-res gallery art photograph, for example, needs different settings when capturing, saving and transferring photos compared to photos on a brochure or a logo for a website.
About Author
Connor Kovack is a Los Angeles based professional photographer & videographer with over 6+ years of experience. Connor is CEO of KovMedia and specializes in Music Videos, Commercials, Photography & More.