Everyday Math

Age Calculator

Date of birth

Age at date

Years old

+ months: 1
+ days: 23
Total days lived: 11,376

Find an exact age in years, months, and days from a date of birth.

By Sam T. · Reviewed by Dr. Lena Ortiz · Updated 2026-06-03

How to use this calculator

Enter the date of birth.
Set the "age at date" — it defaults to today, but any date works.
Read the exact age in years, months, and days.
Use the total-days figure for milestones or countdowns.

Formula

Age = full years, then remaining months and days to the target date

Worked example

Someone born April 12, 1995 is 31 years, 1 month, and 23 days old on June 4, 2026 — about 11,376 total days lived.

Frequently asked questions

How is age calculated?

Count complete years from the birth date, then the leftover months and days up to the chosen date.

Does it handle leap years?

Yes — day counts use actual calendar months including February 29.

Can I find age on a future date?

Yes, set the 'Age at date' to any date you like.

Why does the day count borrow from the month?

When the target day is earlier than the birth day, we borrow days from the previous month, just like manual subtraction.

Is the total-days figure inclusive?

It's the number of full days between the two dates.

Related calculators

Sam T. · Author

Reviewed by Dr. Lena Ortiz · Updated 2026-06-03

Sources

U.S. Naval Observatory — Calendar — Calendar conventions.

Methodology · Report an error

Embed this calculator

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Includes a “Powered by hiinformation” link.

View answer.json (AI feed)

{
  "tool": "age",
  "question": "How does the Age Calculator work?",
  "answer": "Find an exact age in years, months, and days from a date of birth.",
  "formula": "Age = full years, then remaining months and days to the target date",
  "inputs": [
    {
      "id": "dob",
      "label": "Date of birth",
      "unit": null
    },
    {
      "id": "on",
      "label": "Age at date",
      "unit": null
    }
  ],
  "sources": [
    {
      "name": "U.S. Naval Observatory — Calendar",
      "url": "https://www.usno.navy.mil/",
      "note": "Calendar conventions."
    }
  ],
  "updated": "2026-06-03"
}