About Almanac
Almanac works out exactly how old someone is — down to the day, hour, and weekday of birth — from a date of birth and any reference date you choose. It's built for quick, precise answers: form fields, birthday planning, astrology charts, or simple curiosity about a milestone.
Features
- Exact age shown in years, months and days together
- Totals in months, weeks, days, and hours lived
- Countdown to the next birthday with the exact date
- Calculate age as of any date, not only today
- Shows the day of the week someone was born on
- Runs entirely in your browser — no data leaves the page
How to use it
- Tap the "Date of birth" field and pick the birth date, or tap "Type it in" to enter day, month and year manually instead.
- Leave "Calculate age as of" on today's date, or pick another date to see the age at that point in time.
- Tap "Calculate age" to see the full breakdown.
- Tap "Use today" any time to reset the second date back to today.
Frequently asked questions
Can I type my date of birth instead of using the calendar picker?
Yes. Tap "Type it in" above the date of birth field to switch to separate day, month and year inputs — handy on devices where the calendar picker is fiddly, or for entering birth years far in the past.
Can I calculate someone's age on a future or past date, not just today?
Yes. Change the "Calculate age as of" field to any date — past or future — and Almanac recalculates the exact age as of that day.
Does it account for leap years?
Yes. The calculation is based on actual calendar dates, so leap years and varying month lengths are handled automatically and accurately.
Why do the "total days" and "years/months/days" numbers look different?
They answer different questions. Years/months/days breaks the age into calendar units, while total days, weeks and hours show the same age as one running count since birth.
Is my date of birth stored anywhere?
No. All calculations happen locally in your browser. Nothing is saved or sent to a server.
Does this work on mobile?
Yes, the layout and native date pickers adapt automatically to phones and tablets.