Date & time Age

Corrected age calculator

Date of birth

On this date

Weeks born early

Corrected age —

Chronological age less 6 weeks

Both ages

Chronological age —

Weeks since birth —

Days since birth —

Months since birth —

First birthday —

Development uses corrected · vaccines use chronological

Corrected age is the standard basis for assessing development in babies born preterm, normally until about two years. Vaccination schedules follow chronological age. Follow the advice of your health visitor or paediatrician.

Corrected age subtracts the weeks a baby was born early from their chronological age. A baby born six weeks early who is 16 weeks old has a corrected age of 10 weeks — which is the right basis for developmental milestones.

How to work out corrected age

1 Enter the date of birth and how many weeks early the birth was.

2 Read the corrected age alongside the chronological one.

3 Use corrected age for developmental milestones.

4 Use chronological age for vaccinations.

The distinction matters because development runs from conception rather than from birth. A baby born ten weeks early has had ten fewer weeks to develop, and measuring them against a chronological-age chart produces an alarming and meaningless result. Clinicians use corrected age until around two years, by which point the gap has usually closed. Vaccination is the standard exception: those schedules follow time since birth, because immune response does.

Questions

What is corrected age? −

Chronological age minus the weeks born before term. It is the fair basis for developmental comparison.

Until what age is it used? +

Do vaccinations use corrected age? +

How do I know how many weeks early? +

Does it apply to growth charts too? +

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