Illustrator exporting large banner at incorrect size

[chris24825387]

I am trying to export two 20ft wide x 4ft tall banners for a festival. Illustrator won't export the files as the correct size! It is exporting them very very small and will look extremely fuzzy when printed. 

I have one other banner 10ft wide x 4ft tall that I will also need to export. I haven't tried yet but I imagine I'll just run into the same issue.

These files were created by someone else a year ago, I was just uploading some of the information on them. Obviously these files were used to successfully create and print these banners in the past. I do not understand how to make them work now.

Please help, I need to order these banners today. How can I export them as the correct side?

[Monika Gause]

Did you check the size of the artboard?

The export size might be just how this is supposed to be, since it's not uncommon to work in scale. Of course you then need to export at a higher resolution.

[Ton Frederiks · Accepted solution]

You are probably working with a large canvas document in your first example, you need to save as Acrobat 7 or 8 to see the correct size:

some more info on large canvas documents:

https://helpx.adobe.com/illustrator/using/large-sized-artwork.html

and

https://helpx.adobe.com/illustrator/kb/large-sized-canvas-troubleshooting.html

[Brad @ Roaring Mouse]

How are you exporting your document?  PDF? if so, which preset?

Large Canvas documents require PDF v1.6 or above.

[Bobby Henderson]

Another critical wrinkle in the situation: the large format RIP application used to print the banners. Even if the banner artwork is exported in the latest PDF version the file might still load into the RIP 10 times smaller than it should be. Illustrator's large canvas mode is still a pretty new thing. RIP applications usually make it pretty easy to scale artwork. Just double check the artwork size before printing.