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Corrected age calculator
If your baby was born early, their corrected age shows how old they would be if they had been born on their due date. Enter their birth date and either the original due date or how many weeks pregnant you were at birth.
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What is corrected age?
Corrected age, also called adjusted age, takes away the number of weeks your baby was born early. A baby born eight weeks early who is now six months old (actual age) has a corrected age of about four months. Care teams use it to judge whether a baby who arrived early is developing, feeding and growing as expected, because a baby cannot be expected to do everything a baby of the same actual age can do until they have had the same amount of time to grow.
Who needs a corrected age?
Corrected age is usually used for babies born before 37 weeks of pregnancy. Babies born at 37 weeks or later are considered term or early term, and most care teams use their actual age. The earlier a baby was born, the bigger the difference between actual and corrected age.
- Extremely preterm: before 28 weeks
- Very preterm: 28 to 32 weeks
- Moderate to late preterm: 32 to 37 weeks
When to use corrected age
- Milestones: sitting, crawling, walking, first words and social skills. Compare your baby with the corrected age.
- Sleep and feeding: wake windows, number of naps and when to start solid foods often follow the corrected age. Always check with your care team about solids, because your baby also needs to show signs of being ready.
- Growth charts: specialist growth charts for premature babies, or corrected age on standard charts, are usually used for the first one to two years.
When to use the actual age
Vaccinations and routine immunisations are normally given by actual age, not corrected age, even for babies born early. Follow the schedule your care team gives you. Your baby's doctor or health visitor will tell you how long to use corrected age. Many teams use it until around the second birthday, and some stop earlier for babies who were born only a little early.
Guides for the first year
- Use our baby month by month guide, choosing the month that matches the corrected age.
- Read about wake windows by age and milestones in the first year.
- Learn more about vaccinations and check-ups.
Looking for a different tool? See all our pregnancy and baby tools.