Guide · 7 min read

Types of Age: 12 Ways to Measure How Old Someone Is

The main types of age explained, from chronological and biological age to bone, mental and social age: what each one means, how it is measured, and who uses it.

By Sandeep · Updated November 2026

Why There Are Different Types of Age

Two people born on the same day can be very different. One may run marathons at 60 while another struggles with stairs; one child may read at 4 while another starts at 6. A single number cannot capture all of that, so doctors, psychologists and researchers use different types of age, each measuring a different part of a person. Almost all of them are judged against chronological age, the one fixed number we all share.

All Types of Age at a Glance

1. Chronological Age

Chronological age is the exact time since birth in years, months and days. It is objective, the same for everyone born on the same day, and used for school entry, legal rights, retirement and test norms. Read more in what is chronological age.

2. Gestational Age

Gestational age is how far along a pregnancy is, counted in weeks from the first day of the mother’s last menstrual period, often confirmed by an early ultrasound. A pregnancy is full term at 39 to 40 weeks, and a baby born before 37 weeks is preterm.

3. Corrected Age

Corrected age, or adjusted age, is a premature baby’s age minus the weeks they were born early. Doctors use it to judge growth and milestones until about age 2. Work it out with the corrected age calculator.

4. Biological Age

Biological age, also called physiological age, estimates how old the body is based on markers of health, such as blood tests, blood pressure or DNA methylation. Someone who is 50 may have a biological age of 44 or 56. Try our biological age calculator or read chronological vs biological age.

5. Bone Age (Skeletal Age)

Bone age shows how mature a child’s skeleton is. A doctor takes an X-ray of the left hand and wrist and compares it with standard images, such as the Greulich and Pyle atlas. A bone age well behind or ahead of chronological age can help doctors assess growth and puberty problems and predict adult height.

6. Dental Age

Dental age is estimated from which teeth have formed and erupted, usually from a dental X-ray. Dentists use it to plan orthodontic treatment, and forensic experts use it to estimate the age of a person whose birth date is unknown.

7. Mental Age

Mental age is the age level at which someone performs on ability tests. Early IQ scores divided mental age by chronological age. See mental age vs chronological age or the mental age calculator.

8. Developmental Age

Developmental age describes the level of a child’s skills in areas such as language, motor and social skills. Comparing it with chronological age shows whether a child may have a delay. Use the developmental age calculator.

9. Psychological Age

Psychological age reflects how well a person adapts to life: memory, learning, problem solving, emotional regulation and motivation. Two 70-year-olds can have very different psychological ages. In psychology, it is studied alongside chronological age, as explained in chronological age in psychology.

10. Subjective Age and Emotional Age

Subjective age is one of the most personal types of age: it is simply how old you feel. Research consistently finds that most adults feel younger than their real age, and the gap tends to grow later in life. Emotional age is a popular, informal idea of emotional maturity. Online quizzes that give an “emotional age” or “mental age” are for fun, not measurement.

11. Social Age

Social age compares a person’s roles and habits, such as education, work, marriage, parenthood or retirement, with what their society expects at that age. Because expectations differ between cultures and change over time, social age is a flexible idea rather than a fixed number.

12. Functional Age

Functional age describes how well someone can carry out daily activities compared with others of the same chronological age. It combines physical fitness, health and mental ability, and is used in aging research, occupational health and care planning. It is closely linked to adaptive capacity, a person’s ability to cope with physical and mental challenges.

Which Type of Age Matters Most?

It depends on the question. For legal rights, school and test scoring, chronological age is the only one that counts. For a premature baby, corrected age matters. For long-term health, biological and functional age are more telling, and for wellbeing, psychological and subjective age matter. Understanding the different types of age helps you read each number in the right context, and it starts with knowing an exact chronological age. Find yours with our chronological age calculator, or browse every tool in age calculators.

Types of Age FAQs