IQ Range

Prevalence of whole population

Prevalence of LD population

Mild LD

50/55 to 70



Moderate LD

35/40 to 50/55



Severe LD

20/25 to 35/40



Profound LD

Below 20/25



Source: C.Griffiths (Consultant Nurse, Morriston Hospital, 2005)

Please read about the different levels of disabilities in the tabs below.

Mild LD
  • Approximate IQ range 50-69.
  • Likely to result in some learning difficulties in school.
  • Many adults will be able to work and maintain good social relationships and contribute to society.
  • It can be difficult to diagnose a mild learning disability as the individual will often mix well with others and cope with most everyday tasks.  However they may need support in other areas of their lives, such as filling out forms.
Moderate LD
  • Approximate IQ range 35-49.
  • Likely to result in marked development delays in childhood.
  • Most individuals can learn to develop to some degree of independence of self care and acquire adequate communication and literacy skills.
  • Adults will need varying degrees of support to live a good quality life in the community.
Severe & Profound LD
  • Approximate IQ range below 20/25
  • Will require high levels of care and support in all aspects, self care and activities of daily living and will often experience co-morbidities.
  • People with a severe learning disability or profound and multiple learning disability (PMLD) will need more care and support with areas such as mobility, care and communication.