Our editorial standards.
Clear calculations need clear boundaries. We separate reproducible date arithmetic from sourced health context.
Clear rules. Honest explanations.
- A method you can reproduce
- Sources you can open
- No developmental predictions
Calculation rules are documented
The methodology is the reference for our own software conventions: day zero, anchored month ends, leap-day anniversaries and elapsed 100-day counting. Worked examples and automated checks are used to keep calculator pages consistent.
A rule chosen by this tool is labelled as a convention. It is not described as a universal medical or legal rule.
Health context links to the source
Developmental references point to CDC’s published milestone collection. Prematurity context points to AAP parent guidance on HealthyChildren.org. These links are separate from date anniversaries, and the linked organizations do not endorse this calculator.
We do not invent an official checklist for a month that the source does not cover. We also do not infer a child’s development from birth dates alone.
No invented credentials
These pages have not undergone an independent clinical review. We do not claim a doctor author, a medical reviewer or a clinical certification. General information cannot replace individual advice from a child’s healthcare professional.
Updates and correction notes
The visible updated date identifies the date of this content revision. It is not an automatic statement that every external source changed on the same date.
When reporting an issue, include the tool page, expected rule and a non-identifying example. Do not include a child’s real name or date of birth. The contact page can help prepare that note locally.
What makes a useful correction example?
A useful report identifies one rule and a pair of non-identifying dates. “January 31 plus two calendar months should remain March 31” can be checked directly; “the age looks wrong” cannot show whether the issue is day counting, month ends or the selected comparison date.
A source correction should identify the published source and the exact claim to check. A local feedback note is preparation only; no review or response is implied by copying it.