Inputs
For exact age, add time below (optional).
Negative=west of UTC, positive=east.
Options
Batch mode (paste CSV)
Format: Name, YYYY-MM-DD — one per line. Uses the same as‑of date and options.
Result
—
Enter inputs and click Calculate.
Next birthday
Date: —
Weekday: —
Days until: —
Quick facts
- Birth weekday: —
- Age band: —
- Zodiac (tropical): —
Milestones
| Age | Date | Status |
|---|
Milestones are informational only; not legal advice.
Batch results
| # | Name | DOB | Age (primary) | Y‑M‑D | Decimal years |
|---|
How this calculator works
Calendar age uses a true calendar difference between two dates to return years‑months‑days without assuming fixed month lengths. Decimal years divide the exact day span by a chosen year basis (e.g., 365.2425). For exact age, optional time inputs with a timezone offset compute the difference in seconds, then derive units.
FAQs
What’s the difference between calendar age and decimal years?
Calendar age reports years‑months‑days using the calendar (variable month lengths). Decimal years report a single number by dividing day span by a selected year basis.
How are Feb 29 birthdays handled?
Choose a rule: treat non‑leap years as celebrating on Feb 28 or Mar 1. This mainly affects next‑birthday and “years only” calculations.
Why does timezone matter?
Near midnight, local/daylight differences can shift the exact elapsed time. Enable time‑of‑day and set an offset to capture this nuance.
Can I export or share results?
Yes—use CSV/PDF export for batch tables, copy the primary result, or generate a shareable URL with all inputs encoded.
Is this legally authoritative?
No. This tool is informational and may not reflect jurisdiction‑specific rules. Verify with official sources if needed.