Corrected Age for Premature Babies

Age adjusted for prematurity, for milestones and growth. Free, private and instant.

How to use the Corrected Age

  1. Pick baby’s date of birth.
  2. Enter weeks pregnant at birth.
  3. Enter extra days.
  4. Press Calculate to get an instant result with a colour scale, chart and plain-English explanation.

About the Corrected Age

Premature babies are compared with others by their corrected age, which subtracts the weeks they were born early. Enter the birth date and gestation at birth to see the chronological age, corrected age, prematurity group and the date to stop correcting.

Also known as: adjusted age calculator, preemie corrected age, premature baby age calculator, corrected gestational age.

Worked example

Dates in this example are worked out as if today were 5 Nov 2026.

Corrected age: 9 weeks (Moderate to late preterm (32-37)). Born at 32 weeks 0 days (8.0 weeks early), your baby is 3 months 28 days old by birth date but about 2 months 5 days by corrected age. Use corrected age for milestones until about 1 Sept 2028 (2 years corrected).

Formula and cut-offs

Weeks early = 40 - gestational age at birth. Corrected age = chronological age - weeks early. Correct for milestones and growth until about 24 months (corrected).

Frequently asked questions

What is corrected age?

Your baby’s age counted from the due date instead of the birth date, so a baby born 8 weeks early is compared with babies 8 weeks younger.

Until when should I use corrected age?

Usually until 2 years old, sometimes 3 for very premature babies.

Are vaccines given by corrected age?

No. Vaccines follow the birth date, not the corrected age.

Sources and references

Written and checked by the MediHub editorial team against the sources above. Read how we build and review our calculators.

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Last updated . This calculator is for education only and is not medical advice. See the medical disclaimer.