Corrected Age Calculator for Premature Babies
Calculate corrected age from an estimated due date or gestational age at birth, with pre-term, pre-due-date and two-year guidance boundaries made explicit. Sensitive inputs stay in your browser.
Actual age minus 59 days born before the 40-week reference.
Context matters.
- Corrected age is a developmental communication aid for a child born prematurely, not a diagnosis, official-age replacement or substitute for the child's clinician.
Sources & scope
The calculation guide and this source trail show what the result means, where the rule came from and when it was last reviewed. This is source-and-calculation QA, not a claim of medical, legal, tax or other professional review; time-sensitive decisions still belong with the linked authority.
A visible path from input to answer.
Calculate corrected age from an estimated due date or gestational age at birth, with pre-term, pre-due-date and two-year guidance boundaries made explicit. The page keeps the calculation scope and its limits beside the result so the output can be checked, copied or revisited.
- Read the record. The calculator uses How do you want to enter prematurity?, Actual birth date, Estimated due date, Completed gestational weeks at birth and Additional gestational days and 1 additional field supplied in the form.
- Apply the scope. It applies the Prematurity corrected-age communication from estimated due date or gestational age at birth, only within the AAP parent-guidance window — clinician record controls reference and the explicit date, unit and counting conventions shown in the result.
- Expose the checkpoints. Intermediate rows, warnings and timeline events stay visible; the emphasized row identifies the primary checkpoint when one exists.
Actual age minus 59 days born before the 40-week reference.
- Corrected age0 years, 4 months, 0 days
Calculation purpose: Calculate corrected age from an estimated due date or gestational age at birth, with pre-term, pre-due-date and two-year guidance boundaries made explicit. This is a high-sensitivity reference output; the linked authority or qualified professional controls the final decision.
Calendar inputs use plain year-month-day semantics. Leap days, month ends, date-pair order and unsupported dates are checked before the result is shown.
Rule set 1.1.0 · Last reviewed 2026-08-23 · Next review due 2027-02-23. The source panel below contains the linked evidence.
What to know before using the result.
How is corrected age calculated?
Use actual age minus the time born before 40 weeks. CalcSpan can derive that interval from the estimated due date or from gestational weeks and days at birth.
What happens before the estimated term date or after age two?
Before the term-equivalent date, CalcSpan shows the remaining interval instead of a negative age. At chronological age two, it stops presenting a routine corrected-age result and directs interpretation back to the child's clinician.
Is corrected age the same as chronological age?
No. Chronological age always starts at actual birth. Corrected age is a developmental communication reference for a child born more than three weeks early; official records and clinical decisions still use their applicable rules.