How can you tell if a picture is high resolution?

Your most treasured memories, captured on camera and preserved in a custom photo book, deserve to be shown at their best. Mixbookers expect their photo products to be visually stunning, and we take pride in offering the highest quality printing, papers, and finishes. (The New York Times agrees, naming Mixbook the “The Best Photo Book Service” in 2025.) Before your book heads to print, however, there is a very important quality factor to consider—photo resolution.

High-resolution digital photos show more detail than low-resolution photos, and overall are superior in quality, clarity, and sharpness. It’s always best to use high-resolution photos in a photo book or other photo product. But, how can you tell if a picture is high resolution? And what is the best resolution for photo books? Find straightforward answers to those questions below, as we demystify photo resolution and offer practical tips for checking image quality.

Photo resolution 101

Photo resolution measures how much detail an image shows to a viewer. It’s a measure of overall quality. Digital photos are made up of many pixels—tiny squares of color. The more pixels per inch (PPI), the higher the resolution of a digital photo. Printed photos are similarly made up of tiny dots of ink. The more dots per inch (DPI) in a printed photo, the higher its resolution.

Stark differences in photo resolution are clearly visible to the naked eye. Looking at a very high resolution photo, it’s easy to appreciate the clear visibility of small details, even when looking up-close. Low-resolution photos, on the other hand, appear grainy, fuzzy, or blurry, and lack detail. Sometimes low-resolution photos look OK from a distance or at smaller sizes, but reveal their poor quality when you look more closely.

As an extreme example of low vs high resolution, think about vintage video game graphics vs glossy magazine cover photos.

Factors affecting photo resolution

The resolution of a photo is determined by the photographer’s equipment, chosen settings, editing choices, and file-saving methods. DSLR cameras have customizable resolution settings. Different lenses and digital vs optical zoom also affect resolution. Smartphone camera resolution, measured in megapixels (MP) varies by model and make. With scanned photos, the settings on the scanner determine resolution.

Any decent digital camera or smartphone camera in 2025 is capable of taking high-resolution photos. Low-resolution is more commonly an issue for the following:

• Photos taken with older, lower quality digital cameras or cell phones.
• Photos taken off social media (which are compressed into smaller file sizes).
• Photos sent via email (which also get compressed). If you want to use someone else’s photos in your photo book, invite them to collaborate on Mixbook and upload the original files.
• Photos that were prepared for online viewing, which generally needs a lower resolution (and file size).

Measuring photo resolution: DPI & PPI

The two common ways of measuring image resolution—DPI and PPI—are often used interchangeably. In fact, the DPI to PPI ratio is 1:1, meaning a photo with a resolution of 300 DPI also has a resolution of 300 PPI.

While similar, technically DPI is the measurement of resolution for printed photos, whereas PPI is the measurement of resolution for digital photos viewed on a screen. Scanners also use DPI measurements as they pick up data points from a printed image.

What is considered a high-resolution picture?

The precise DPI/PPI that is considered as a high-resolution picture depends on its intended purpose and scale. However, the standard for a high-resolution photo for print is generally considered 300 DPI/PPI or higher.

Mixbook recommends using photos of 300 DPI or higher for all photo book projects for a high-quality finish. This doesn’t mean photos with a resolution lower than 300 DPI/PPI are unusable; it only means their print quality will be lower.

How can you tell if a picture is high resolution?

Beyond a basic visual assessment of a photo’s clarity, there are easy ways to find out the resolution of a digital photo in DPI/PPI. The information is contained in the file’s metadata, and can be found using your computer or smartphone.

On a PC: Locate the digital photo file in File Explorer. Right-click the file, select Properties, then Details. Scroll down to find the resolution (shown in DPI under “Image”).

On a Mac: Open the Finder app and locate your photo file. Right-click and select Open With>Preview. Hover over Tools and select Show Inspector. Find the resolution (in DPI) and more info in the pop-up window.

You can also find the resolution of a digital photo using most photo management or photo editing software and apps, including on a smartphone. Look for menu items such as “image size” and “properties,” or refer to the instructions.

When you’re editing photos to use for a photo book, pay attention to the export/save settings. Make sure to save high-resolution versions of the photos.

Resolution & file size

Generally, the higher the resolution of a photo, the greater the file size. This means you can look at file size to get a rough idea of a photo’s resolution. According to Adobe, a JPEG file at 300 PPI will have a file size around 3.5 MB. A low-resolution photo at 72 PPI will have a file size around 500 KB.

How important is high resolution?

For photo books, there’s a broad range of acceptable photo resolutions. High-resolution is more important for larger print sizes and for photographs with small details. If you want to include a panoramic landscape shot across a two-page spread in a large book, a high-resolution photo is essential. With smaller printed images, such as thumbnail shots, the resolution can be lower without visibly affecting print quality.

Photos with a resolution in the range of 240 to 300 DPI/PPI should still print well at most sizes, and resolutions in the 180 to 240 DPI/PPI range might be fine in smaller formats.

Tip: Visit this Help Desk post for a full breakdown of recommended file formats and quality specs for Mixbook photos.

Mixbook Studio™’s low-quality warning

If the resolution of a photo you’re using in a photo book project is too low for acceptable print quality, Mixbook Studio™ will display a low-quality warning. This appears as a red circle with an exclamation mark, plus a pop-up message reading “Please resize to be smaller or use a higher resolution photo.”

If you do not see any low-warning messages in Mixbook Studio™ or at checkout, and your photos appear clear and sharp in preview mode, you can be confident that your photos will print beautifully.

Read more about warnings: The Red Exclamation Point That You Don't Want to See in Your Photo Book

Do your high-resolution photos appear blurry on screen? See this Help Desk post for an explanation.

What to do with low-resolution photos

If your photo triggered a low-resolution warning, reconsider using that photo in your Mixbook. If you still want to use it, either accept that the print quality will be low, or try adjusting the size of the photo to be smaller. A low-resolution photo might trigger a warning if you place it in a full-page frame, but be OK in a thumbnail-size frame. A collage of smaller photos is often a visually appealing composition, and it’s a great way to include low-resolution photos you love.

Read more about photo quality in our ultimate guide: Choosing the Best Photos for Your Photo Books: Avoiding Quality Downgrades