Best Image Size and Resolution Settings for Printing

In this tutorial, we look at the relationship between image size and resolution and how it affects printing. This will help to guide you in selecting settings and finding the best resolution size when making a print. We also consider how to deal with the image aspect ratio and the need (or not) to include a border.

Understand Image Size

There are various ways that we can measure image size. One is the size of the image on the disk which we measure in bytes. Another, and most important for printing is the dimension of the image which we measure in pixels. This is extremely important if you want to achieve the best quality photo prints for images like this one.

If the image you are printing doesn’t have enough pixels for size of the print you are making, it won’t produce a photo quality print. What determines if there are sufficient pixels for the print is the resolution size.

A common way to measure the resolution size is with the dpi value which is short for “dots per inch”. If the resolution of your image doesn’t allow the printer to produce enough dots per inch on the paper, the image won’t look like a photograph.

As a rule of thumb, to achieve photo quality print, you will need to use an image resolution of 300 pixels per inch. We write this as 300 DPI and means that in each inch of your print there will be 300 pixels.

Too Many or Too Few Pixels

A common mistake when printing is to assume that if you create a resolution size greater than 300dpi, it will produce a higher print quality. This isn’t the case and could even cause your print quality to reduce by damaging the image sharpness.

If we send an image to a printer that has too few pixels for the print size required, the printer tries to make up for the missing pixels. This can create a pixelated image that might look OK from a distance, but which won’t stand up to close inspection.

When we try to use an image with too many pixels per inch, the printer throws away the pixels it doesn’t need. This can damage the image sharpness. Whilst the image will appear OK, it won’t appear as sharp as it might look on a computer screen.

To reproduce an image as a sharp photographic print you need the correct resolution which is approximately 300dpi. It can also important to sharpen the image for print output as the process of printing will soften the image.

The Printer Used is Important

Assuming a print resolution of 300dpi is a general rule to help you understand the resolution you need for a photo quality print. But not every printer uses 300dpi. Some inkjet printers like the Epson work best with a print resolution of 360dpi. Some wide format printers use a lower resolution like 254dpi.

If you are using your own printer, assume you need a print resolution of 300dpi unless it’s an Epson printer. For Epson inkjet photo printers assume a resolution of 360dpi.

If you are using a third-party print service, check the website. If the website doesn’t say contact them for advice. Failing that, use a resolution of 300dpi.

Calculating Required Image Size Using Resolution

Now you understand the resolution for making a photographic quality print it’s easy to calculate the pixel dimensions of the image. All you need to do is multiply the dimensions of the print you’re making by the required dpi resolution (let’s assume 300dpi).

For example, if you are making a 16×12-inch image print, the pixel resolution of the image would be 4800 × 3600. That’s 16×300 = 4800 pixels and 12×300 = 3600 pixels.

It’s also important that you apply any output sharpening after you have resized your image. If you’re unsure of how to resize your image I have a tutorial explaining how to resize an image in Photoshop. There’s also a similar tutorial explaining how to resize and image using affinity photo.

Consider the Print Border

Something that’s frequently forgotten when making photo prints is the print border.

If your printer or print service supports borderless printing, this is easy. The print measurement is a simple calculation like the one above. But what if you need to leave a border or the image is a different size to the paper. This is when you need to allow for the border when calculating the resolution size for the print.

There are several scenarios that could exist:

1. The image has the same aspect ratio (width to height) as the paper.
2. The image has a different aspect ratio to the paper.
3. You want to leave a border around the edge of the image.

Let’s go through these in a little more detail.

Image and Paper Have Matching Aspect Ratios

This is the easiest option as you can either print with a border or borderless.

If you decide to make a borderless print you should calculate the size of the image (in pixels) using a photo resolution. If the paper measures 16×12-inches you would multiply each side of the image by the required resolution for your printer. The print will then fill the paper at the best resolution for a photo print.

Image and Paper Have Different Aspect Ratios

The important decision in this scenario is “do you want to leave a border around the image”. If you don’t, you will need to crop the image to match the aspect ratio of the paper. If you aren’t sure how to do this and use Affinity Photo, see my tutorial explaining how. If you are using Photoshop then this tutorial explains how. Alternatively, you could trim the paper after printing.

If You Want to Leave a Border

You first need to consider the size of the paper in relation to the image. If the image and paper have different aspect ratios, the border around the edge won’t be even. For example, you could have a larger boarder on the long edge compared to the short edge. This can look acceptable up to a point but then may start to look odd if the difference in size is too great.

The only way to resolve this is to crop the image to match the paper aspect ratio. Alternatively trim the paper after making the print.

Next, consider the size of the border you want to leave. The assumption here is that any print you make is centred on the paper. Most printers have an option to do this and many print services do this by default (or give you the option).

If you are printing on an 18×16-inch paper and want to leave a 1-inch boarder around the edge you can calculate the image size by reducing the paper dimensions by 2-inches. The image size then becomes 16×14-inches.

To produce a photographic quality print at 300dpi resolution you need an image that’s 4,800 pixels wide (16 x 300) by 4,200 pixels high (14 x 300). When you centre the image on the paper, at a resolution of 300dpi it will leave a 1-inch border around each edge.

An alternative is  to produce an image with a border of the required size and make a borderless print. This tutorial explains how to add an image border in lightroom but you can use other applications to achieve the same effect.

Conclusion of Best Image Size and Resolution Settings for Printing

To achieve the best quality prints, it’s important to size your image correctly for the print. When you know the dimensions of the print you want to produce, you can calculate the correct pixel dimensions using the resolution size for printing.

The best resolution for printing is generally accepted as 300dpi although this can change depending on the printer used. For an Epson printer use 360dpi and for other makes assume 300dpi. If you are using an online print service check their requirements as some larger printers may use different settings.

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