Print file size inflated when exporting in Photoshop

[nicoleo14243317]

I'm creating files in photoshop to be printed as posters–the largest size is 20 in x 30 in with a resolution of 300. The files are large, but when I File > Export > Export As... and export the file as a JPG, the file size is very large (around 50 MB). Based on files that others have created at this same size, I think they should be around 11 MB. 

I can't reduce the quality as they are intended to be printed. All layers in the file are flattened. Even when I try to export a blank document, the file still exports to be over 8 MB.

I've seen posts on the forum about removing document ancestor metadata–however, I can't figure this out. Does anyone know how to fix this?

Thanks!

[jdanek]

"removing document ancestor metadata"... not sure you'd gain enough or deminish the size enough dealing with metadata(?).  You could Save As > Photoshop PDF ( copy ) after you convert to RGB.  The print vendor would then convert your Photoshop PDF to CMYK for printing.  Converting to RGB slashes one channel out of your file, thereby reducing the size approximatly 25%.  But, even with all of this fancy foot work, a 20x30 300ppi file at 50mb is pretty reasonable.

[jazz-y]

The size of the garbage metadata can be quite large (I've seen files with ~ 50 MB of records in the documentAncestors section). If you use the new "export as" or the old "save for web" then it is enough to select "none" in the metadata option - all metadata will be deleted after export. If you use "save as" or "save a copy", then unnecessary metadata can be removed using a script. You can find examples in Metadata Bloat - Abnormally large PSD files when I save them

[r-bin]

app.activeDocument.xmpMetadata.rawData = "";

also try this Flattened file retains large file size