Guides/Age in completed months

Age in completed months only

Pediatric schedules and milestone charts often ask for age incompleted months, not years. That is “how many month birthdays have passed,” not a decimal year.

Basic idea

• From DOB to as-of date, count whole months that have finished.
• Born 10 Jan; on 9 Mar → 1 completed month; on 10 Mar → 2 completed months.
• Same birthday logic as completed years —completed years·Y/M/D breakdown.

Worked examples

1. DOB 15 Mar 2025; as-of 15 Sep 2025 → 6 months.
2. DOB 15 Mar 2025; as-of 14 Sep 2025 → 5 months completed.
3. Need total days instead:age in total days.

Uneven month lengths

February and 31-day months make “same day next month” ambiguous for some DOBs (e.g. 31 Jan → Feb). Clinics usually document their rule; when unsure, prefer an as-of calculator —age from DOB·past as-of.

Tool

Age Calculatorreports years, months, and days you can read as completed units.