DPI, PPI and resolution for scrapbookers

PPI vs DPI

People often use the terms PPI and DPI interchangeably. However, they mean slightly different things. PPI stands for pixels per inch. It describes exactly how many image pixels are printed in one inch of paper.

DPI stands for dots per inch. This strictly describes the physical printer ink dots a machine puts on the page.

For digital scrapbooking files, you are dealing with PPI. When you read about setting your software to 300 DPI, it really means 300 PPI. You do not need to worry about the printer ink dots.

The printer handles that part automatically. Just remember that both terms usually refer to the same idea when you are working on a computer. Understanding this basic concept is a great first step when learning What is digital scrapbooking?.

Why 300 is the standard

The number 300 is the usual target for sharp prints viewed close up. A scrapbook page is something you hold in your hands and look at closely. If you print at a lower number, the image might look soft or pixelated.

The standard digital scrapbook page is 12 x 12 inches at 300 pixels per inch. This means the file is exactly 3600 x 3600 pixels in size. When you set up your canvas in your software, choosing 300 ppi ensures your final layout will look crisp.

You might also hear about 72 ppi. The number 72 ppi is an old screen convention and does not matter for printing. Screens completely ignore ppi.

A web image only needs enough pixels to fill the screen space. You can read more about standard formats in our guide to page sizes and printing.

Pixels are what count

What really matters for your final print is the pixel size of the image. The ppi setting is just an instruction for the printer. Changing the ppi number without changing the pixels only changes the print size.

It does not change the quality of the image file itself. This is called printing without resampling.

For example, a file that is 3600 x 3600 pixels prints 12 inches wide at 300 ppi. If you change the instruction to 150 ppi, that exact same file prints 24 inches wide. The pixels remain exactly the same.

Adding pixels to a small image is called upsampling. Upsampling cannot add missing detail. It just makes the image look softer. It is always better to start with a large file.

The resolution formula

You can easily figure out how large an image will print using a basic formula. To find the print size in inches, you take the pixels and divide by the ppi. To find the needed pixels, you take the inches and multiply by the ppi.

Here is an example using a standard photo size. A 1200 x 1800 pixel photo prints at 4 x 6 inches at 300 ppi. If you print that same photo at 8 x 12 inches, it would be only 150 ppi.

That means it might look a little blurry on your page. Knowing this formula helps you plan your layouts. You can learn more techniques in our guide to photo editing basics.

To check your math, try these steps:

• Decide how many inches wide you want to print your photo.
• Multiply that number by 300.
• Check if your image file has at least that many pixels.

Checking your photos and supplies

Phone photos today usually have enough pixels for a 4 x 6 or larger print. You rarely need to worry about new pictures from a modern camera. However, old small images from early digital cameras or the internet may not have enough pixels for a good print.

This is especially true when Scanning old photos and memorabilia for scrapbooks. Always check the pixel dimensions of your older photos before printing.

When using digital supplies, you will notice different file types. Digital papers are usually JPG files. Elements and alphabets are transparent PNG files.

A good quality kit will provide these files at a size large enough for a 300 ppi layout. If you drag a small photo or element onto a 3600 x 3600 pixel canvas and stretch it to fit, it will become blurry. You can find more details about file formats in our article on png vs jpg.