Difficulty Ratings.  The rating levels of difficulty are easy, moderate, and difficult. The guidelines below are from the Trip Leaders' Handbook.

Difficulty Hikes Bike Trips Ski Trips Snowshoe Trips Canoe Trips
Easy - Accessible to all in good physical condition; suitable for families with children. less than 5 miles and less than 1,000 ft. of elevation gain less than 15 miles, fairly flat less than 6 miles, fairly flat less than 3 miles, less than 800 ft. of elevation gain less than 5 miles, flat water
Moderate - Requires a degree of stamina; some previous experience is desirable. 5 to 8 miles, 1,000 to 2,400 ft. of elevation gain 15 to 35 miles, flat or moderate hills 6 to 10 miles with less than 1,000 ft. of elevation gain 3 to 6 miles with 800 to 2,000 ft. of elevation gain 5 to 8 miles for flat water, less than 5 miles for Class I or II rapids
Difficult - Challenging events for people in good physical condition; previous experience necessary. more than 8 miles or more than 2,400 ft. of elevation gain more than 35 miles or with long uphill sections more than 10 miles or more than 1,000 ft. of elevation gain more than 6 miles or more than 2,000 ft. of elevation gain more than 8 miles for flat water, more than 5 miles for Class I or II rapids, or any Class III or 1V