I generally use the fairly universal 100 point rating system. I use this system when I am able to sample a wine over the course of a few hours to fully rate how a wine progresses.
If I am not able to follow a wine’s progress, I either just give a full tasting note with no rating or use the dreaded letter grade, like school. If I use the letter grade, here are the applicable point ranges:
A – A very good to great wine (93 – 100)
B – A good to very good wine (87 – 92)
C – A drinkable and enjoyable wine in most circumstances (82 – 86)
D – A wine with notable flaws, sweet, too soft, unripe, etc. (75 – 81)
F – Run away! (50 – 74)
A plus rating (+) means a wine is near the top of the range, a minus (-) means a wine is at the lower end of the range.