Why 80%?

Every pair starts at 46. Then each letter adds points: E/I (how you hang out): E and I → +6 · S/N (what you talk about): both N → +18 · T/F (how you handle drama): T and F → +4 · J/P (who plans): both P → +6. 46 + 6 + 18 + 4 + 6 = 80.

For comparison, the same two types score 99% in our love-match rule, which rewards opposite E/I and T/F instead.

Both rules are our own design, not an official MBTI product, and personality types are not a science of friendship.