Age Calculator
Find your exact age in years, months and days, total days and weeks lived, your next birthday, the day of the week you were born and your zodiac sign.
Age Calculator: with the default inputs, age is 36.
Defaults to today. Change it to find your age on any past or future date.
Completed years.
- Exact age
- 36 years, 3 months, 26 days
- Next birthday
- May 15, 2027
- Days until next birthday
- 247
- Days lived
- 13,267
- Weeks lived
- 1,895.3
- Months lived
- 435
- Day of the week you were born
- Tuesday
- Zodiac sign
- Taurus
Assumptions
- Dates are calendar dates; time of day and time zones are ignored.
- A month is complete on the same day of the next month, or the last day of that month if it is shorter.
- Leap-day birthdays fall on 28 February in common years.
| Milestone | Date | Days from now |
|---|---|---|
| 15,000 days old | June 9, 2031 | 1,733 |
| 20,000 days old | February 15, 2045 | 6,733 |
| 25,000 days old | October 25, 2058 | 11,733 |
How this is worked out
The formula
age = completed years between date of birth and the "as of" date months = whole calendar months (day of month clamped: Jan 31 + 1 month = Feb 28) days = days left over after the last whole month total days = calendar days between the two dates (leap days included)
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Date of birth
- A calendar date.defaults to 1990-05-15
- Age on this date
- Defaults to today. Change it to find your age on any past or future date.defaults to today
What you get back
- Agemain answer
- Completed years.
- Exact age
- Next birthday
- Days until next birthday
- Days lived
- Weeks lived
- Months lived
- Day of the week you were born
- Zodiac sign
What this assumes
- Dates are calendar dates; time of day and time zones are ignored.
- A month is complete on the same day of the next month, or the last day of that month if it is shorter.
- Leap-day birthdays fall on 28 February in common years.
About this calculator
Enter a date of birth and the calculator returns age in completed years, the exact age in years, months and days, the total days and weeks lived, the next birthday and how far off it is, the day of the week of the birth, and the Western zodiac sign. Change the second date to find someone's age on a past or future date — for a form, a school cutoff, or a retirement date.
How the exact age is counted
Age is not simply days ÷ 365.25. The calculator counts whole calendar months first, then the leftover days, which matches how people, schools and governments count birthdays. Someone born on 15 May is exactly "1 month" old on 15 June whether that month had 30 or 31 days.
When the birth day doesn't exist in a later month (born on the 31st, looking at February), the month is counted as complete on the last day of that month — the same convention used by the ISO 8601 duration rules and most legal systems. Total days, on the other hand, are exact: every leap day between the two dates is included.
Leap-day birthdays
If you were born on 29 February, your birthday in common years is counted here as 28 February. Some jurisdictions (the UK, New Zealand, Hong Kong) legally treat it as 1 March; most US states use 28 February. Either way you age one year per calendar year, not one per four.
Reading the results
- Age is completed years — what you'd write on a form.
- Exact age is years, months and days.
- Days lived and weeks lived are exact counts; months lived is whole calendar months.
- Next birthday shows the date and the countdown. Zero days means it's today.
- Milestones lists your next round-number day counts and the day you turn one billion seconds old (about 31.7 years).
Common uses
School and sports registration ("must be 5 by 1 September"), pension and Social Security eligibility, visa and passport forms that ask for age at a specific date, and settling arguments about who's older by how many days. For gestational age or a due date, use the pregnancy due date calculator instead.
Frequently asked questions
▸How do I calculate my age from my date of birth?
Subtract the birth year from the current year, then subtract one if this year's birthday hasn't happened yet. For months and days, count whole calendar months since the last birthday, then the leftover days.
▸How many days old am I?
Count the calendar days between your birth date and today, including leap days. At 30 years old you've lived roughly 10,957 days; the calculator gives the exact figure.
▸When is my birthday if I was born on February 29?
In leap years it's 29 February. In common years most places celebrate on 28 February (this calculator's convention); the UK and a few others legally count 1 March.
▸Why does my age in months not equal years × 12 + months?
It does — 'months lived' is total whole calendar months, so 34 years and 2 months shows as 410 months. Days left over are not converted into fractional months.
▸Can I find my age on a specific date?
Yes. Change 'Age on this date' to any past or future date. The calculator returns an error if that date is before the date of birth.
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