Age Calculator
Find your exact age from your date of birth — years, months and days, plus totals in weeks, days and hours, the day you were born, your next birthday countdown and your zodiac sign. All in your browser.
About the age calculator
This tool works out your exact age from your date of birth. Enter your date of birth and, optionally, an as-of date (it uses today if you leave it blank). It then reports your age several ways:
- Calendar breakdown — your age as years, months and days, where each unit is the remainder after the larger ones. This is the natural "26 years, 5 months and 7 days" form, and it accounts for months having different lengths and for leap years.
- Flat totals — your whole age expressed in a single unit: total months, total weeks, total days and total hours lived.
- The weekday you were born on — e.g. Thursday.
- Your next birthday — the date and a countdown of days until it.
- Your zodiac sign — the Western (tropical) sun sign for your birth date.
Everything runs locally in your browser. Nothing is uploaded to a server, and it works offline.
Accepted formats
You can use any of these for either field:
2000-06-22(date only)2000-06-22T08:30:00or2000-06-22 08:30:00(the time is ignored)2000-06-22T08:30:00Zor...+02:00(RFC-3339 — the offset is dropped)2000/06/22,06/22/2000(US month/day/year), and22.06.2000
How age is computed
Age is counted by stepping the calendar forward, not by dividing a number of seconds. So if you were born on the 31st, a month later (in a shorter month) is still counted as a full month, and a span crossing Feb 29 in a leap year is handled correctly.
FAQ
How is age in months and days calculated?
First whole years are counted (you only gain a year once your birthday has passed), then whole months past that, then the leftover days — so the breakdown always sums back to your birthdate.
What happens with a Feb 29 birthday?
In years that are not leap years your birthday is treated as Feb 28 for counting purposes, and the next-birthday date falls back to Feb 28 too.
Does it handle time zones?
Dates are compared as wall-clock values. If you paste a timestamp with an offset (Z or +02:00), only the date part is used.
Is my date of birth sent anywhere?
No. The calculation happens entirely in your browser; nothing is uploaded.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool age-calculator "2000-06-22"New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/age-calculator/?birthdate=2000-06-22&as_of=2026-06-22Machine-readable descriptor: tool.json — title + parameters JSON Schema for agents.