Hike and walk ratings consist of a number-letter code where the number is the distance and the letter is the amount of uphill climbing Grade Elevation Gain. A Mini-hike is 4 miles or less and has an elevation gain of 500 ft or less.
Distance
1: Up to 6 miles
2: 6 - 10 miles
3: 10 - 15 miles
4: 15 - 20 miles
5: over 20 miles
A: Up to 1000 ft
B: 1000 to 2000 ft.
C: 2000 to 3000 ft
D: Over 3000 ft
E: Over 3500 ft
So a hike rated 2B means that the distance covered will be from 6 to 10 miles and the total elevation gain will be between 1000 and 2000 ft.
Click below to link to the Local Sierra Club WEB Site