What is the Difference Between PSB and PSD Photoshop File Formats

Many specialized apps use their own proprietary formats to store program-specific data, and Photoshop is no exception. It uses two different file formats, PSD and PSB, depending on the size of the document you want to save. 

In this article, you’ll learn the difference between PSB and PSD files, when to use them, and how to save your Photoshop file as PSB or PSD. 

Key Takeaways

  • PSD and PSB files are both native Photoshop file formats that can store all the information that can be created or read by Photoshop.
  • PSD files are intended for typical usage, while PSB files are intended for extremely large files
  • PSD files have a pixel dimension limit of 30,000 x 30,000 pixels and a file size limit of 2 gigabytes.
  • PSB files have a pixel dimension limit of 300,000 x 300,000 pixels and a file size limit of 4.2 exabytes (4.2 billion gigabytes).

What is a PSD File?

PSD is an acronym for PhotoShop Document, and it is the most common Photoshop file format by far. PSD files can contain all the information you see in your Photoshop document, including pixel information, alpha channels, layers, masks, smart objects, swatch palettes, and anything else you can create or open in Photoshop.

PSD files do have some limitations, though. The maximum pixel size of a PSD document is 30,000 x 30,000 pixels, and they also have a file size limit of 2 gigabytes. If you need to create a larger document, you have to use the PSB file format.

For context, 30,000 x 30,000 pixels works out to a whopping 900 megapixels, while most high-end DSLR cameras take pictures between 24 and 50 megapixels. Unless your project involves a lot of image stitching or you use hundreds of layers in your document, you’ll rarely reach the limits of the PSD format. 

What is the Advantage of the PSD File Format?

The biggest advantage of using the PSD file format is compatibility between different programs. The PSD format can be opened by most of Adobe’s other Creative Cloud applications like Illustrator and InDesign so that you don’t have to convert your PSD files to another format before including them in another project. 

PSD files can even be opened by other image editors such as GIMP, Affinity Photo, and Photopea, although some of the newer Photoshop features, like smart objects and smart filters, will not load properly in these other apps.

What is a PSB File?

PSB is almost identical to PSD, except that it is designed for much larger file sizes and pixel dimensions. PSB is officially known as the Large Photoshop Document format, but many users claim it stands for PhotoShop Big (or PhotoShop Bloated if you want to be cheeky about it, although I can’t find any mention of either of these names in any official Adobe documentation.) 

Whatever it stands for, PSB files can still hold all your Photoshop document information just like a PSD file, although most other Adobe apps cannot open PSB files. Lightroom Classic recently got an update for displaying PSB files with a few size limitations, but Illustrator and InDesign cannot open them or place them into documents.

Additionally, all the non-Adobe apps that show off their ability to open PSD files cannot open PSB files. 

What is the Advantage of the PSB File Format?

The only advantage to using the PSB format instead of PSD is that it allows you to save much larger files. 

PSB files have a pixel dimension limit of 300,000 x 300,000 pixels, and the file size limit is a truly incredible 4.2 exabytes. If you’ve never heard of an exabyte, don’t worry – 4.2 exabytes is equal to 4.2 *billion* gigabytes, or 4200 terabytes! I don’t know if there’s a computer in the world capable of processing an image that large, but I guess it’s only a matter of time.

(If you were curious, 300,000 x 300,000 pixels is equal to 90 gigapixels or 90,000 megapixels.)

Suffice it to say, you won’t have to worry about file size limitations when using the PSB file format. 

Who Uses PSB Files?

If you’re a casual photographer who uses Photoshop for your own private photography practice, you may never run into a PSB file. 

Typically, they’re used by professional technical photographers who want to create extremely high-resolution composite images, which makes for extremely large file sizes. They’re also frequently used in various scientific fields for the same reason, often for composite images from deep-space observatories. 

Saving Your Photoshop Work in PSB or PSD Format

Saving your work as a PSB or PSD file is extremely simple! 

Open the File menu, and click Save As. Photoshop will open the new Save to Creative Cloud dialog window, but you can get to the standard ‘save file’ dialog window by clicking the On your computer button in the bottom left corner of the window, as shown below.

Enter a descriptive name for your file, and then select your desired format from the dropdown menu, as shown below. 

To save it as a PSD file, select Photoshop. 

To save as a PSB file, select Large Document Format.

If you try to save a file that’s too large for the PSD format, Photoshop will not allow you to select the PSD file format, and it will automatically default to PSB.

A Final Word

That covers everything you need to know about the differences between PSB and PSD file formats in Photoshop! For most day-to-day uses, PSD files are the better choice for their better compatibility. If you want to work on an extremely high-resolution image or you love to use hundreds of layers, then the PSB format is a better choice – just remember that PSB files aren’t compatible with most other Adobe apps. 

Whichever format you choose, have fun!

About Thomas Boldt
Thomas started his Photoshop career way back in 2000. After exploring Photoshop 5.5 in a high school computer lab, he developed an enduring passion for photography, design, and technology that carried him through a Bachelor of Design degree and into the wild world of tech startups.

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  • Tom

    Hi Thomas,

    Thanks for sharing your thoughts on the differences between these 2 file formats.
    I would just like to add that it’s not uncommon at all to come across the need to save as .PSB instead of .PSD when you work in 16 bits rather than 8 bits.