To be a �Prominent Peak�, a hill must have 500 m of elevation above sea level. Although some traditional hill lists do include the 500 m summits and below, many hill walkers may have a view that the UK�s mountains start at 2000 feet, 610 metres or perhaps 600 metres.
The Prominent Peak lists have as their focus a hierarchy of hills based on the 1-2-5 Principle. In topographical terms, we believe the most important hills are the 3 P1000s followed by the 155 P500s. Whilst many of the best-known hills in the UK are included, there are 6 P500s which have an elevation below 600 metres. If you accept the concept of the importance of P500s, then it follows automatically that their minimum qualifying height is 500 metres.
The authors have gone on to extend this same criterion (elevation greater than 500 m) to P200s and P100s. This does produce a large database of 1564 hills in the UK. Even in the southern half of the UK, when you get above the 500m contour the terrain can seldom be described as 'agricultural' or even 'rural'. There is almost always a sense that you are on high ground. Most frequently such land is used to rear sheep or grouse. Of course, there are numerous fine walks with superb views in the countryside below 500 m but the vegetation is often different and that 'high ground' feeling absent. Drawing up a height qualification of 500 m fits well with our overall thinking with regard to Prominent Peaks and restricts the database to the UK�s higher terrains.
It is convenient to classify the UK Prominent Peaks into more than one group of summit heights. The authors classify the heights into three groups as defined in the table below.
| Height category | Min criteria | Max criteria |
| H500 | 500 m | 749 m |
| H750 | 750 m | 999 m |
| H1000 | 1000 m |
A graphical representation is given below.
A significant benefit of this definition, especially when compared with traditional lists, is that the thresholds for classifying peaks into height groups match major map contours.
This means that it is easy for a map user to identify to which height group a particular peak belongs.
We do want to encourage users of the lists to consider attempting the 158 peaks with a prominence of at least 500 m (P500+); which is called Bloomer�s Challenge. Nevertheless, there are opportunities presented within the UK Prominent Peaks Database to focus on higher summits either the H1000s or the H750s.