Why does photoshop think a file is larger than it is? Forces me to save as PSB.

[artkeh]

I don't know if this is a bug or I'm just interpreting it incorrectly. But, this has happened to me many times. Completely random times, no way to recreate it or know if/when it will happen. But it happened again today for the first time in many months. Photoshop tells me it can't save a file because it's over the 2GB limit and needs to be saved in Large Document Format. But the file isn't anywhere even close to 2GB. As you can see in the second pic it's at 990MB. But it forces me to save it as a PSB anyway. And yes, the file really was around 990MB and not 2GB. Not sure why this happens.

I'm on a Mac, saving to an external hard drive. Latest release versions of both Photoshop and MacOS. But, it's been happening for years so this goes back many versions.

[davescm]

The size at the bottom left is the size in RAM and is based on the pixel width x pixel height x 3 (or x 6 for 16 bit/channel images) and then the number of layers. But here is the catch - any smart objects just show as if they were a single pixel layer at document size. In reality they could contain larger documents, multiple layers and even further 'nested' smart objects. So that Doc Size number at the bottom left of the screen is not a reliable indicator of the size required to save on disk.

There is a further complication when saving, depending on settings in Preferences File Handling. Compression can reduce the saved file size on saving , whilst both meta data and 'maximise compatibility', which adds another flattened layer, can increase it further. None of this is calculated until the actual save to disk.

Dave