For Beginners
FAQ: Why 300 PPI/DPI?
By Shelleyrae Cusbert 2005
Jul 15, 2005, 02:15

One of the most commonly asked questions is in regards to resolution. The intricacies of resolution is not the easiest information to understand or explain, this article will attempt to explain why digital scrapbookers are recommend to use a resolution of 300ppi and dpi in their work.

The terms PPI – Pixels Per Inch, and DPI- Dots Per Inch, have become fairly interchangeable when talking about digital media but there is a difference.

Technically DPI refers only to how many dots per inch a printer is capable of printing. Almost all printers are now capable of a dpi much higher than 300ppi.

PPI refers to how many pixels per inch the digital image actually contains irrespective of how many dots per inch (dpi) a printer is capable of producing. Digital images are similar to mosaics – each digital photo is made up of small picture elements (pixels) of a different colour – these are what creates the picture.

Pixels are arranged in a rectangular area. By multiplying the number of pixels across by the number of pixels down you have the maximum number of pixels a digital camera, for example, can deliver, eg, a photo with pixel measurements of 1600x1200 equals a 1,9200,00 or 2MP image. A Megapixel (MP) is a million pixels. A digital image is limited to a maximum number of pixels eg a 3MP camera produces an image with 300000 pixels.

If you attempt to increase the physical size of an image above the limit of its pixel resolution (ppi) the result will be a pixilated or poor quality image, no matter the dots per inch resolution (dpi) it is printed at. If we take a digital photo and reduce its size the pixels compress, and pixels are discarded. If you expand the size of the photograph the pixels stay the same size and you will see an effect called pixilation – you begin to see the individual pixels that make up the image.

The correlation between dots (pixels) and inches is seen in the table below. As the human eye cannot discern quality levels over 300dpi in printed material, 300dpi is the chosen, and industry, standard for high quality print images. 

Digital scrapbookers need to ensure that each element in a layout has the required pixels per inch (ppi) to create a quality print at 300 dots per inch (dpi). For example, to convert the dimensions for a 1500 x 1200 image being printed at 300 ppi you divide as follows:

Width: 1500 pixels χ 300 ppi = 5"

Height: 1200 pixels χ 300 ppi = 4"

This gives you a maximum print size of 3inches x 5inches before the quality begins to degrade.

So an 8 x 10 print would require:

Width: 2400 χ 300 ppi = 8”

Height: 3000 χ 300 ppi = 10”

All of the elements of a layout, including the canvas, need to be of 300ppi to create a quality print and if any of these elements are increased in size past their pixel capability you will see the effects of pixilation.

Of course using 300ppi does require more computer processing power (RAM) and more hard memory. It is suggested that if necessary 200ppi can be used with little difference in quality perceivable between 300ppi and 200ppi. This can be a viable alternative but depends on your printing methods. It is best to do test prints at home or wherever you normally print at both resolutions to judge the difference.

It is also important to consider that magazines require a resolution of 300ppi for all published work. If you scrap at 12”x12” then you can resize down while still retaining 300pi but if you scrap at 8”x8” and are using 200ppi then your layout, which is often required to be of about 8 inches in width, does not have a high enough resolution for their requirements.

Many online stores also only accept work at 300ppi so this should be taken into account should at any time you decide to sell your designs.

If you will want to edit the photograph later – especially if you want to enlarge or crop the photo you will need to increase the resolution accordingly. For example:

6” x 4” print @ 300dpi = 6” x 4” print @ 300dpi

6” x 4” print @ 600dpi = 12” x 8” print @ 300dpi

6” x 4” print @ 1200dpi = 24” x 16” print @ 300dpi

This will mean for example that you can safely crop the 6x4 print scanned at 600dpi to a more standard size 8”x10” or smaller without losing quality. The quality of a scanned print is especially important with heritage photographs that require restoration or editing.

Hopefully this article has improved your understanding of resolution and why 300ppi is considered to be the best choice. Scrapbook-Bytes continues to support 300ppi as the best resolution option for digital scrapbookers’ precious memories.