Trekking in Nepal can be categorized in different sections according to the level of difficulty. Lower altitude treks are regarded as easy and ideal where as higher altitude or alpine treks fall upon moderate, strenuous, very strenuous and technical or challenging. The more higher you go, the more physical fitness and acclimatization are required. Vertex Holiday explains you about different categories of difficulty level in brief.
Easy (Grade I)
The easy trip or Grade I does not require acclimatization or hard physical labor to climb and can be done by any type of trekkers of all ages. The treks do not exceed over 3000 meters (except a short hike over this altitude). The trekking days include about a week or below 10 days. Every day, you walk about 5 hours and goes through the communities and forests. Local culture offer wonderful memories of the trip.
Moderate (Grade II)
Moderate Treks range from 3000 meters to 5000 meters altitude. Good physical fitness and acclimatization are the necessary aspects. Generally, you walk for 5-6 hours each day but you may have to walk about 6-7 hours according to the destination and walking speed. The trail can be little bit rocky and rough (or sometime off-the-beaten) having several ups and down. This includes about two weeks of itinerary. Moderate trips are more isolated than the easy ones.
Strenuous (Grade III)
The trails of strenuous trip go over 5000 meters altitude and are rough. On the winter, there will be snow. You must be very fit to do this type of treks. They can include high Himalayan passes. Temperature level will be at o or in minus. Nights are chilling. You should be very fit and highly acclimatized. Strenuous trips may be complicated for those having bad medical condition.
Very Strenuous (Grade IV)
Very strenuous trekking requires some of the climbing skills. The trips range from 4000 meters to 6000 meters. You need to be physically fit and acclimatized to walk in the alpine altitude for 7 hours or a bit more. About 2-3 weeks of itinerary fall in such trips. Snow covered passes and using climbing equipments project the identity of the trip. Such trips go far more from the human settlements. For many days, you may not see them.
Challenging (Grade V)
Challenging trips are suitable for the high adventure seekers. It ranges from 6000 meters above. Along with high physical fitness and acclimatization, you should have previous trekking experiences and good knowledge on using climbing equipments. Challenging trips include 16-28 days itinerary including high passes and glaciers. Every day you walk about 7 hours that can be 8-9 hours based on the destination and the situation. Far remote destinations fall under this category.
Note: Though trekking category range from easy to challenging, each trips should not be underestimated and your fitness and acclimatization level should be updated.