How Big Should Digital Files Be?

Does size matter?

If you are unsure about how big your digital files should be, then this article is going to simplify the way you save or export your images. I have a few simple rules that I live by that will make your life a little easier.

Low res vs high res

Most photographers don’t know the real difference between high and low res images. They have a general idea, but the specifics are fuzzy, low res, if you will… And that’s totally fine! There is an endless supply of things we don’t know yet. The most important thing is that we keep learning.

Firstly, the ‘res’ is short for resolution, and simply describes the number of pixels in an image or on a screen. My full frame camera produces images that are 5760×3840 pixels. The long side of the image is 5760 pixels long, and the short side is 3840 pixels long. In the geometry world, multiplying the dimensions will give you the ‘area’. Resolution is the ‘area’ of the image measured in (mega)pixels instead of inches or meters. In my case, 5760px x 3840px = 22,118,400px. This means that my images are 22 megapixels. (1 megapixel = 1 million pixels).

Rather than define them by a certain size, I classify them by their use. If the file is going online or anywhere else to be viewed digitally, it will be delivered as low res. If it is going to be printed, it is going to be high res.

One size doesn’t fit all

Imagine using a generator to power your TV remote. Or have you tried using 2 AA batteries to start your car? Those both sound absurd, right? This is the same logic behind choosing the right resolution and dpi for your images. If you have too large an image for digital use, it will take too long to load, or you simply won’t be able to upload it at all. Most platforms and websites limit the size of the images you can upload. On the flip-side, if you tried to print a 30″x45″ canvas from a 1 megapixel image, it’s going to be too pixelated to recognize. It will look like a mosaic, or like a scene from Minecraft. The trick is to size your images so they are perfectly clear without having any extra data.

What is dpi?

So now you know what resolution is. You can see how many pixels are in an image. Dpi measure how densely those pixels are packed in. Dpi (or ppi) measures dots per square inch, or pixels per square inch. So in 1″x1″ section of an image, how many pixels are there? A 72dpi image has fewer pixels per square inch than a 300dpi image. 72dpi is the density we use for online purposes and 300dpi is standard for printing images.

Bringing resolution and dpi together

Let’s get mathy here for second. We’ll use an 8×10 image for this example. If you are going to print an 8×10, and you need 300dpi for ideal print quality, your image will be (8×300)x(10×300) pixels. So, 2400x3000px is the resolution you need. If you are sharing it digitally online, your image will be (8×72)x(10×72) pixels, which is a resolution of 576x720px. If you do that math, your print size image will be about 14.8 times larger than your facebook-friendly version. That’s a pretty big difference. That’s a lot of extra data you don’t need to upload if you’re not going to print the image.

High res

High res images are best for print. They include the most amount of data possible for the file. Export your images at 300dpi (or ppi), and if you have to set a pixel dimension, make it longer than your camera can produce. This prevents accidentally shrinking your image. Here’s an example of my settings when I export my images to print. Make sure you also select the option “don’t enlarge”.

 

Low res

Low res images are best for sharing online. They include just enough data to show a good image, but still load quickly and no one can save the image and print it. Many platforms, like Facebook, will automatically resize your photos if you upload something too large, and their software will drastically reduce the quality of your image. Facebook is notorious for making photos look pixelated. This means they drop the dpi too low for the resolution. Again, it will look like a scene from Minecraft. Here are the settings I use to share photos digitally. Notice the resolution is set to have 1200px on the longest side. I reduce this down to 900 for places like Facebook or when I put them on my website.

 

Using presets

Presets will save you tons of time. I have options for print, web use, and the different slideshow programs I use. This makes it easy to export my images at the exact resolution and dpi necessary for each application. Spend a few minutes programming some presets and your workflow will be that much quicker without ever having to cut corners.

So there you go! If you have any other questions about which size to use or what any of this means, don’t hesitate to ask! Post your questions in the comments below or shoot me an email and I’m happy to clarify for you.

Happy resizing, photogs!

About the Author Mike Lloyd

Mike is the Tim Burton of photography. He tells powerful, imaginative stories with cinematic photography. He specializes in dramatic, film-noir style boudoir and epic cinematic portraits. He's also the creative force behind Photogs Unite! which focuses on learning from professionals outside the photography industry to learn marketing, sales, branding, and everything else you need to know to build a thriving photography business. And burritos are the key to his happiness.

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