Green rounds are the ones your handicap is built from: your best recent scores.
You get a first handicap after 3 rounds. It settles down around 8, because from then on it's built from your best 2 or more scores. The full system looks at your last 20 rounds and averages your best 8. Older scorecards from this year count too, so add them with their real dates.
Each round gets a differential: how your score compares to the course's difficulty (its rating and slope). Your handicap is the average of your best 8 differentials from your last 20 rounds. With fewer rounds, we use fewer of your best ones, the same way the official system does.
Course rating is what a scratch golfer should shoot from those tees, like 71.3. Slope says how much harder the course plays for an average golfer. 113 is average and 155 is the toughest. Both are printed on most scorecards.
Each tee has its own rating for men and for women. We'll remember your pick.
Find these on your scorecard, usually next to the tee colors.
For a handicap, one disaster hole shouldn't count in full. Each hole counts as no worse than double bogey plus your strokes on that hole. Add your bad holes and we'll do the math.