How to Check Pixel Size and Resolution Before You Print Images or Submit to Competitions

Pixel Perfect: A Simple Guide to Image Size and Quality

Have you ever submitted a photo to a competition or tried to print it large, only to be told the resolution is too low? You’re not alone! In my Facebook photography group Love Your Lens, I often see gorgeous images that sadly don’t meet the technical requirements for printing or exhibiting. The good news is: it’s not that hard to understand once someone explains it in plain English. So, let’s break it down.

What Is Image Resolution Anyway?

When we talk about image resolution, we’re really talking about how much information your image contains – specifically, how many pixels. Pixels are the tiny coloured dots that make up a digital photo. The more pixels your image has, the more detail it can show and the bigger it can be printed without going blurry or pixelated.

Pixel Dimensions vs. PPI

Let’s get clear on two common terms:

• Pixel Dimensions are the total number of pixels in your image, measured in width and height. For example, 4000 x 6000 means your photo has 4000 pixels across and 6000 down – that’s 12 million pixels (24MP).

• PPI (Pixels Per Inch) tells you how many of those pixels will be used to fill one inch of printed space. Higher PPI = more detail. For high-quality prints, you usually want 300 PPI.

Here’s a quick example:

• If your image is 3000 pixels wide and you print it at 300 PPI, you’ll get a 10-inch wide print (3000 ÷ 300 = 10).
• Want a 20-inch print? You’ll need an image that’s 6000 pixels wide at 300 PPI (6000 ÷ 300 = 20).

What About Megapixels?

You’ve probably seen cameras and smartphones advertised as having 12MP, 24MP, or even higher. MP stands for megapixels, which just means millions of pixels. A 12MP camera takes photos that are roughly 4000 x 3000 pixels in size (because 4000 × 3000 = 12,000,000). The higher the megapixel count, the more detail the image can potentially capture – and the larger you can print it without it going blurry. But remember, how you use and save the image afterward (like cropping, compressing, or taking a screenshot) can reduce that resolution – so even a fancy camera doesn’t guarantee a print-ready file unless you're careful (more on this shortly).

How to Check the Pixel Dimensions Without Photoshop / Lightroom

It's usually relatively easy to check the pixel dimensions of your image, but people are often stumped about checking the resolution (the pixels per inch) especially if they are not using editing software like Lightroom or Photoshop. But don’t worry – here are some simple ways to check:

✅ Mac (via Preview)

1. Open the image in Preview.
2. Go to the menu and choose Tools > Adjust Size.
3. You’ll see the Resolution (PPI) listed there – often 72 or 300.

Important: Make sure “Resample image” is not ticked if you're just checking, not changing anything.

✅ Windows (Free Option: IrfanView)

Windows doesn’t show PPI in the usual Properties window, but here’s a quick workaround:

1. Download the free app IrfanView.

2. Open your image in IrfanView.

3. Press I on your keyboard or go to Image > Information.

4. Look for Resolution (DPI) – it’s usually listed as X DPI and Y DPI.

Note: DPI (dots per inch) and PPI (pixels per inch) are often used interchangeably when talking about image resolution on screens.

✅ Online Tool (for Everyone)

Anyone (Mac, Windows, phone users) can use:

Photopea.com

1. Open the site and drag in your image.

2. Go to Image > Image Size.

3. You’ll see both pixel dimensions and resolution (PPI).

Bonus: You can even change the PPI here if needed – just make sure “Resample” is not checked unless you actually want to resize the image.

How Resolution Gets Accidentally Reduced

This is such an easy mistake to make. Here’s how it happens:

• Cropping: Cutting off part of your image removes pixels. If you crop heavily, your resolution drops fast.

• Screenshots: Taking a screenshot of an image instead of using the original – especially on phones – gives you a much smaller file.

• Social Media downloads: If you upload to Facebook or Instagram and then download it later, the image is compressed and downsized.

• Emailing from your phone: Many email apps automatically reduce image size when you attach a photo. Watch for “Small, Medium, Large, or Actual Size” – always choose “Actual Size” if you’re sending for print or a comp.

• Exporting from editing apps: Some apps reduce resolution when saving. Check export settings and choose the highest quality option available.

How to Avoid Losing Quality

• Always keep an original high-res version of your image.

• Be careful when cropping – you're literally throwing away pixels and resolution.

• Use cloud services (like Dropbox or Google Drive) to share full-size images.

• When exporting from apps, look for terms like “Maximum Quality” or “Original Resolution”.

• Avoid editing and saving multiple times in apps that compress (like some phone editors) – each save can reduce quality a bit.

I hope this has helped take the mystery out of image resolution! If you’ve still got questions, feel free to pop a comment below  – no such thing as a silly question.

Happy shooting (and printing)!