Simplified handicap index estimate from your recent round scores.
A simplified approximation of the USGA method (average of the best half of your score differentials × 0.96) — not an official handicap index.
A differential normalizes a round's score against the difficulty of the course played: (Score − Course Rating) × 113 / Slope Rating. The 113 is the slope rating of a course of "standard" difficulty, so differentials from different courses can be fairly compared.
The USGA-style method is designed to reflect playing potential rather than an average day, so it takes only the best half of your entered differentials (rounded down, minimum of 1) and averages those before applying a 0.96 multiplier.
No — this is a simplified approximation of the method for personal tracking. An official handicap requires posting scores through an authorized golf association system, which can apply additional adjustments this calculator doesn't make.