Hi, what is the size in pixel for 10 feet by 130 feet billboard (printer = 900 DPI)?
There are numerous calculators available on the web.
What a weird question to ask on a forum, you can even ask Chat GPT these days. Or if your oldschool like me, just open Photoshop and set your document to this size and DPI.
Or simply use the good old print size assistant in 3dsMax. Nobody seems to know about that one…
Rendering->Print Size Assistant.
Also, what you’re trying to do is impossible. The resolution needed for this would be 100.000px+
900 DPI is insanely high for billboards. Usually, billboards are printed below 100 DPI, and values between 15 and 50 are common.
you get what I mean here, but my client keep asking me to do this size of rendering even though I told it is un-necessary, finally he told me his printing guy said his printer is 900 DPI, normally how you guy will do to deal this kind of client?
Well I explain it with science (viewing distance, etc) and then I tell them the price of rendering something this big out (don’t mention AI upscaling) and talk to the printer guy directly.
Hehe…yes I feel your pain - I have also been asked to render ridiculous sizes for print. The fact is that they just don’t understand image
resolution or the calculations involved.
As was mentioned, in this case it would be literally impossible to render at that size, plus I don’t believe Photoshop or anything else would be able to open a document of that size.
Show your client this random (out of probably 10s of 1000s of similar pages) page Image Resolution for 3D Rendering and Animation: A Quality Guide
I call the printing guy, the printing guy throw back an question to me, he ask: “are you new in 3d rendering field, you do not know what 900 DPI, calculate from there”, i am speechless…do not know how to respond
thanks for sharing the page, i have share it to my client, hoping he can read and understand, I am thinking to drop the job…what do you think?
Dropping the job is certainly an option, although I would always try to educate the client, as that can show that you are acting
with their best interests in mind, so it’s added value for them, as you are in fact saving them an enormous amount of money and time 
Ok, I try to discuss with them again, thank you to all the help and suggestion here.