Age across cultures, one screen

Age isn't a single number once you cross cultures. The same person can be 38 by the international system, 39 by the Korean way of counting, and a different traditional age in Japan. This tool gives you all three at once from a single birthdate, plus zodiac, generation, days-alive, and the next birthday countdown.

International age

The standard international age equals (current year − birth year) if your birthday has passed, otherwise (current year − birth year − 1). It's the legal age used for U.S. federal law, IRS filings, voting, drinking, and most global contexts.

Korean age (셈나이)

Korean age starts at 1 at birth, then every January 1 everyone ages one year. So if you're born in late December, you're "two years old" within a week of being born. Korea's law was unified to international age in June 2023 for legal/medical purposes, but cultural conversation — birthdays, family gatherings, K-drama dialogue — still uses Korean age.

Year age (연나이)

Year age is simply (current year − birth year), regardless of birthday. Used for Korean school cohort enrollment, military service eligibility (age 20), and youth-protection age thresholds (age 19 for alcohol/tobacco).

Zodiac, star sign, and generation

From the same birthdate, the tool shows your East Asian zodiac animal (rat, ox, tiger…), your Western astrological sign, and your generational cohort (Millennial / Gen Z / Gen Alpha). Useful when filling out cultural surveys or chatting with family across time zones.

Share the result URL

The Share button at the top right copies the current result URL to your clipboard. Send it to a family group chat or save it as a bookmark — all your birthday-related cards in one link. Inputs live only in the URL query string. Nothing is sent to our server. 100% in the browser.

FAQ

Three age-calculation traps people fall into

1. "Age 21" but different state laws kick in at different points

In the U.S., turning 21 unlocks legal drinking nationwide — but other "age 21" thresholds aren't uniform. Concealed-carry permits can require 21 in most states but 18 in a few; gambling age varies 18–21 by state and game type; renting a car typically requires 21 (often with a young-driver surcharge until 25). The tool's "legal milestones" card shows the most-cited federal ages (16 drive, 18 vote/contract, 21 drink, 26 off parental insurance, 65 Medicare) — but state-specific rules override federal in many cases. Always confirm with the relevant state's DMV, ABC board, or insurance department for binding decisions.

2. Birthday on Feb 29 — leap-year babies and "official" age

Roughly 1 in 1,461 people are born on Feb 29. Most U.S. jurisdictions treat the legal age increment as occurring on March 1 in non-leap years, so a Feb 29, 2004 baby legally turns 21 on March 1, 2025 — meaning they can't legally drink until that date, not Feb 28. A handful of states use Feb 28 as the increment day; check your state. The tool computes age based on the calendar elapsed, which matches the March 1 convention used by most DMVs and ABC boards. Driver's license expiration dates follow the same logic.

3. International dates — born abroad, living in the U.S.

If you were born in a country east of the date line (Korea, Japan, Australia, much of Asia), your birth certificate's local date may be one day ahead of the U.S. date at the same moment. For passports, visa applications, and SSA records, the U.S. typically uses the birth-country local date as printed on the birth certificate — not converted to U.S. time. The tool accepts any ISO date; enter the date exactly as printed on your birth certificate, not a "converted" version, to match official records.

This guide reflects general usage as of the post date. Legal age requirements vary by jurisdiction — consult local authorities for binding decisions.