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Age Calculator

Accurately compute age from date of birth.

Date & TimeUpdated 2026-04-05• Author: CalcDock Team, Editorial• Reviewed by: CalcDock Team, Editorial review: legal-age disclaimer, leap-day note (Apr 2026)

Find your exact age in years, months, and days — accurate to the day. Enter your date of birth and optionally choose a custom "as of" date to calculate age at any point in time, past or future. Leap years are handled automatically. Includes Korean man-nai (만 나이) for Korean administrative contexts.

When this calculator helps most

Use for personal planning or verifying age at a specific “as of” date — not as a substitute for legal identity documents.

What each input means

Date of birth — Calendar birth date used as the start of the age interval. (YYYY-MM-DD)
As of date — Reference date for the age (defaults to today). (YYYY-MM-DD)

Input mistakes to avoid

•Enter DOB in the correct calendar (Gregorian vs local display).
•For leap-day births, confirm how your jurisdiction treats Feb 29 in common years.

Age Calculator

Date of Birth*

As of Date

Leave as today, or enter any past/future date

🔒Inputs are processed in your browser and are not sent to our servers.

Formula

The age is computed by comparing the birth date to the current date. Years are counted by full calendar-year boundaries, then remaining months and days are derived. Leap years (Feb 29 births) are handled by rolling forward to Mar 1 in non-leap years.

Examples

Standard age calculation

Born January 1, 2000 — calculating age as of January 1, 2025.

→ 25 years, 0 months, 0 days — Total: 9,131 days lived

Leap year birthday (Feb 29)

Born February 29, 2000 — calculating age as of February 28, 2025 (non-leap year).

→ 25 years, 0 months, 0 days (Feb 28 used as birthday in non-leap years)

Age at a past date

Born June 15, 1990 — how old were they on January 1, 2000?

→ 9 years, 6 months, 17 days

Age at a future date

Born March 25, 1991 — how old will they be on March 25, 2031?

→ 40 years, 0 months, 0 days

Birthday has not yet occurred this year

Born December 1, 1990 — calculating age as of March 25, 2026.

→ 35 years, 3 months, 24 days (birthday in December not yet reached)

How to read your results

→Age in years increments on each birthday; months/days count the remainder after full years.
→Legal age for voting, drinking, or contracts uses statutes — they may differ from casual “age” displays.
→Leap-day births: many jurisdictions assign Feb 28 or Mar 1 in non-leap years — confirm locally.
→Korean 만 나이 follows international-style counting for many official purposes since mid‑2023 reforms.

What this result means

Chronological age from date arithmetic — administrative systems may round or use different rules.

Common Pitfalls

⚠️Forgetting that the birthday has not occurred yet in the current year — age is one year less until that date.
⚠️Leap‑day birthdays (Feb 29) in non‑leap years — most systems use Feb 28 for legal purposes.
⚠️Not using the "As of Date" when you need age at a past/future date.
⚠️Confusing different age systems — many countries now use international standard (man‑nai in Korea).

Tips

✓Use the "As of Date" field to check your age on a specific date — past or future.
✓Leap year birthdays (Feb 29) are automatically treated as Feb 28 in non-leap years.
✓Korean man-nai (만 나이) shown in results is now the official Korean standard since June 2023.
✓For school enrollment eligibility checks, set the "As of Date" to the cutoff date used by the institution.
✓For retirement planning, set the "As of Date" to your planned retirement date to confirm your age.
✓For official document verification, confirm the exact age definition used by the issuing authority.

How to check your results

✓Compare y/m/d increment to a known milestone (e.g., birthday just passed).

Warnings & Limitations

⚠️Legal definitions of age can vary by context (e.g., as of specific cutoff dates). For official documents, confirm with the issuing authority.

What this calculator does not tell you

–Statutory age for drinking, voting, or contracts — laws define edges and time zones.
–Gestational age or medical “age” — different domains.

Frequently Asked Questions

Is the result accurate to the day?

Yes. It counts complete years, then remaining months and days on the calendar, including leap years.

How are Feb 29 birthdays handled?

In non-leap years, most systems treat Feb 28 as the birthday for legal purposes.

Sources & References

Report an issue with this calculator

Editorial & review note

Outputs are chronological age from calendar math; Korean 만 나이 labels follow documented policy shifts. Statutory age rules (contracts, alcohol, voting) are jurisdiction-specific—never inferred from this display alone.

Editorial Policy