Walk Grading for all A Walks Explained
24-27 - Easy Walk - Moderate Pace - 5 hours duration approx
28-32 - Moderate Walk - More demanding Walk - 5-6 hours approx
33-36 - Difficult Walk- Lots of climbing at a fast pace - for experiences walkers only - 6hrs +
37-40 - Strenuous - Fast pace with very demanding climbs for VERY (underlinded) expeienced walkers only

Easy 

May be signposted trails but will still require some basic navigation skills and some hillwalking experience. Mainly on easily identifiable paths, with good underfoot conditions. Can include open countryside with some rough ground and moderate ascents.
For example: Spinc walk in Glendalough or Diamond Hill in Connemara National Park

Time: 2 -5 hours Height gain: 250-500 metres Distance: 5 - 12km

Moderate 

Hillwalking experience and navigational skills in difficult weather conditions are required. Can include more informal paths, rougher, boggy and more uneven terrain with the possibility of rocky, moderately steep ground.
For example: Derrybawn and Mullacor Loop in Wicklow or Slieve Binnian in the Mournes

Time: 5-7 hours Height gain: 500-800 metres Distance: 10-15km 

Difficult 

Good hillwalking experience with capable and proven navigational skills in all weather conditions required. Underfoot conditions could be rough and uneven with the possibility of prolonged rocky and steep sections and mountain terrain without clear paths. An ability to deal with mountain hazards, steep ground and scree is essential.
For example: Carrauntoohil, Mweelrea, Lugnaquilla

Time: 6-8 hours Height gain: 800-1000 metres Distance: 12 - 20km

Strenuous 

A good level of fitness, hillwalking experience and proven navigational skills in all weather conditions are essential requirements, as is an ability to deal with complex mountain terrain. Open moorland, mountain plateau, rocks and cliffs without clear paths. There may be some exposure and a need for some basic scrambling skills. Route finding challenging so close attention to navigation is key.
For example: Eastern Reeks ridge, Coomloughra Horseshoe in the McGillycuddy Reeks

Time: 8-10 hours Height gain: 1000-1500 metres Distance: 12 – 25km

Challenging 

A high level of fitness, hillwalking experience and proven navigational skills in all weather conditions are essential requirements. Extended walking in mountainous and often remote terrain, with the possibility of exposure, may involve steep ascents and descents with some extended scrambling. Potential navigation difficulties so hillwalkers should have confidence in their ability to navigate in all weather conditions, including at night. Fitness, stamina and experience at walking and leading at a strenuous level is a basic requirement.
For example: Muckish-Errigal Ridge in Donegal , Maumturks traverse in Connemara

Time: 8-14 hours Height gain: 1500 metres and above Distance: 20–30+km

Note:

The above grades are all based on the assumption the route can be completed in reasonable weather conditions. Adverse weather and changes in ground conditions may increase the risk and grade of the walk substantially. Time, height gain and distance should be taken into consideration collectively when selecting a route for a particular grade. All the above grades exclude hiking in full winter conditions where very low temperatures and substantial snow and ice may be encountered. In these conditions crampons and ice axe may be required, along with the skills and experience necessary to use them safely.

This grading system is set out by Mountaineering Ireland, to provide a national benchmark for anyone who is selecting routes for club walks, gatherings, events and group walks etc.

*Distance is not a reliable measure of the level of difficulty. https://www.mountaineering.ie/hillwalking/HillwalkingGrades/default.aspx

B Walks

All B walks are generally approx - 3-4 hours long at a very moderate pace involving some low-level climbing generally.

Thursday and Saturday Walks

Thursday Night and Saturday Morning walks are generally about 2 hours long as an easy and leisurely pace.