Supposed to is the conventional spelling of the adjectival phrase meaning required to, expected to, or allowed to. But the nonsensical suppose to is common—for example:
It does what it’s suppose to do at least as well as any other stick I’ve used … [Wired]
Capps has been a proven closer and was suppose to be the early option if Nathan didn’t seem ready. [Fergus Falls Daily Democrat]
Suppose to might be considered incorrect in formal contexts. Elsewhere, it’s not a serious error.
Examples
A nurse who was supposed to be caring for elderly people got intoxicated on painkillers … [Scotsman]
It was supposed to be a number-packed speech about budgeting and spending and all manner of fiscal gobbledygook. [Politico]
As a journalist, I know I’m supposed to be objective. [Edmonton Journal]
I don’t even know what a ylang ylang is, let alone what it is supposed to smell like. [Sydney Morning Herald]
