Age Calculator
With date of birth Fri, June 15, 1990, age on Fri, October 2, 2026, age comes to 36 years old — age. It is reached in 6 steps, the last of which is 2026 - 1990 - (1 - 1), and each one is printed on the page with its numbers filled in. The formula is the one published by NIST, not an approximation fitted to it.
Exact age in years, months and days from a birth date, plus the total days lived and the next birthday.
Formula and sources checked · How we check
Date of birth 1990-06-15, Age on 2026-08-17
36 years old
Age for the example below. Editing a field recomputes the calculator below; this figure holds the answer the page was loaded with.
It is written into the HTML rather than drawn by a script, so a search engine reading this page without running JavaScript still finds an answer.
- Days lived
2026-10-02 - 1990-06-1513,258 days- Age in years
2026 - 1990 - (1 - 1)36 yr- Age in whole months
(2026 - 1990) * 12 + (10 - 6) - (1)435 months- Months since the last birthday
435 - 36 * 123 months- Weeks lived
floor(13258 / 7)1,894 weeks- Hours lived
13258 * 24318,192 hours
Worked example
Someone born on 15 June 1990 is 36 on 17 August 2026: the birthday has already passed this year, so it is a straight subtraction of the years. Two months and two days on top of that, and 13,212 days in total.
How to work it out yourself
- 1.Enter the date of birth. The second field defaults to today, so leaving it alone answers "how old am I".
- 2.Set the second date to age someone at a moment that is not now — on a policy renewal, at the start of a school year, on a court date.
- 3.The years figure counts completed birthdays. Somebody two days short of turning forty is thirty-nine, which is how every legal age threshold works.
The formula
- Days lived
2026-10-02 - 1990-06-15 - Age in years
2026 - 1990 - (1 - 1) - Age in whole months
(2026 - 1990) * 12 + (10 - 6) - (1) - Months since the last birthday
435 - 36 * 12 - Weeks lived
floor(13258 / 7) - Hours lived
13258 * 24
Source: NIST — the Gregorian calendar and leap-year rule, US Social Security Administration — a person attains an age the day before the anniversary of birth
Questions people actually ask
- Why not just divide the days by 365.25?
- Because it drifts. Dividing gives the right answer most of the time and the wrong one near a birthday, around leap days, and for anyone born on 29 February. Counting completed birthdays instead — subtract the years, take one back if this year's birthday has not arrived — is exact for every date and is the way age is defined legally.
- How is the age of someone born on 29 February counted?
- In a common year they have no birthday, and every US jurisdiction treats them as attaining the new age on 1 March. This calculator does the same: the day and month comparison puts 29 February before 1 March, so the year turns over on the first day the date could exist.
- Does age turn over on the birthday or the day before?
- Everyday usage says on the birthday, and that is what this shows. US Social Security uses the common-law rule that a person attains an age at the first moment of the day before the anniversary, which matters for benefit eligibility dates and almost nothing else. If you are working out a benefit date, subtract one day.
- Does this account for time zones?
- It counts whole calendar days in UTC, so it never gains or loses a day to a time-zone boundary. A birth date is a calendar fact rather than an instant, which is why hospitals record the local date and not a timestamp.
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