2.5 average. The old saying "2 and a half kids, a dog and a white picket fence" used to be cliche for a reason. Slightly above replacement but not so much it's reflecting you're worried 3/4 of your kids will die like places where they have 8 kids expecting 6 will die before they reach adulthood.
Means some families will have 1, some will have 4-5 but on the overall it evens out to something sustainable and (assuming immigration is under control) slow enough growth that housing and jobs can slowly grow to match without too much pressure.
Someone said earlier in the thread that "overpopulation" was an issue even in the west but that's horseshit.
We bloated the population to an absurd degree in an incredibly short amount of time through unchecked immigration, and that doesn't even include illegal immigration.
I would bet a good chunk of change if we'd had the opportunity to slowly grow the population to our current levels much more gradually we wouldn't be having as much growing pains as we do now. It's all about the rate of growth, especially if it out paces resources. The US is nowhere near "overpopulated" and the same applies to the west. It's just infested.
Remove that by deporting illegals, crippling H1Bs and similar, and vastly slowing the rate of legal immigration and stopping illegal immigration as much as possible (plus bring jobs back from offshoring and outsourcing) and a lot of problems go away.
tl;dr they all have to go back. Every single one.