What temperature rating do I actually need for winter camping?

Specialist-community consensus on r/CampingGear and r/WinterCamping is that manufacturer ratings often reflect 'limit' (survival) rather than 'comfort,' and most experienced winter campers recommend choosing a bag rated 10–15°F colder than the lowest temperature you expect. For true winter use below freezing, that typically means a 0°F or lower bag for most sleepers.