We find that when both hands are balanced, with no five-card suits, three notrump and four of a major don’t become good contracts (likely to make more often than not) unless there are at least 26 combined HCP. For details, see the Valuation Exercise at the start of Real World Bridge 6: The Game Zone.
However, when there are long suits, very good game contracts can be reached on many fewer than 26 combined HCP. In these situations, we find that HCP are not nearly as important. Instead, the most important factors include how many trumps you both have, your shape, and whether your Kings and Queens and Jacks tend to be in partner’s long suits as opposed to partner’s short suits. For example, here is a deal that occurred in a large online Open Pairs in January 2025:
Eleven tricks were easy in spades, despite only 17 combined HCP. Notice that the Jack of clubs and Queen-Jack of hearts could have been small cards, and there still would have been eleven tricks with spades as trumps.