PSB (large Photoshop)
Also known as: psb file, Large Document Format, .psb, Photoshop Big
PSB (Large Document Format) is Photoshop’s file type for documents too big for the standard PSD — beyond 30,000 pixels per side or 2 GB in size. It stores the same editable layers as a PSD but is built for huge canvases, so PSB files are often very large.
- Photoshop’s Large Document Format (.psb)
- For files over 30,000 px or 2 GB
- Often very large; same editable layers as PSD
When PSD isn’t big enough
The regular PSD format caps out at 30,000 pixels on a side and a 2 GB file size. For panoramas, gigapixel composites, large print artwork, or deep layer stacks that exceed those limits, Photoshop uses PSB, the Large Document Format.
A PSB holds the same editable contents as a PSD — layers, masks, smart objects, adjustment layers — just without the size ceiling. It supports documents up to 300,000 pixels per side.
Why PSB files are heavy
Because PSB exists for the biggest projects, the files are usually among the largest you will encounter, sometimes many gigabytes each. The size comes from the huge canvas plus all the preserved editable layers.
Keep a PSB while the project is active. When it is finalized, export a flattened TIFF, PNG, or JPEG for sharing, and archive the working PSB off your main drive to recover space.